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Scutellaria baicalensis Georgi extracts and its active compound baicalin promote tomato seedling growth

  • # Authors contributed equally: Genzhong Liu, Jinyang Xin

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  • Excessive use of chemical fertilizers and pesticides causes pollution of soil, water, and the atmosphere. Biostimulants are derived from natural sources, which can help plants absorb nutrients and promote plant development. Chinese herbal medicine extracts are enriched with bioactive compounds and therefore hold great potential for developing novel biostimulants. In this study, the predominant active compound, baicalin, was detected in Scutellaria baicalensis Georgi ('Huangqin' in Chinese) extracts via LC-MS/MS. To explore their effects, we used three different methods to treat tomato seedlings with Scutellaria baicalensis Georgi (S. baicalensis) extracts or baicalin, including foliar spraying (S), root irrigation (R), and the combination of foliar spraying and root irrigation (SR). Both S. baicalensis crude extracts and commercial baicalin promoted stem and root development, enhanced the photosynthetic capacity, and increased tomato seeding biomass, eventually making tomato seedlings grow vigorously. Clustering analysis and principal component analysis showed that S. baicalensis extracts and baicalin had very similar effects and showed the best effects in SR treatment. S. baicalensis extracts and its active compound baicalin could promote tomato seedling growth, suggesting that S. baicalensis is a potential source of biostimulants.
  • Passiflora plants are lianas with axillar tendrils and nectaries; their sexual organs are merged into a structure named the androginophore[1]. Passiflora is a genus with nearly 600 species; 95% of them are American natives, mainly from South America and Mesoamerica (from Central Mexico to Panama)[2]. More than 60 species of Passiflora produce large edible fruits, and nearly 25 species are cultivated. The economically important edible juice producers are Passiflora edulis, P. edulis f. flavicarpa, P. ligularis, P. quadrangularis, and P. tripartita var. mollissima; moreover, the fruits of P. tripartita, P. tarminiana, P. maliformis, P. alata, P. hannii, P. laurifolia, P. popenovii, and P. setacea are consumed locally elsewhere[3]. Approximately 1.5 million tons of passion fruit (Passiflora edulis) are produced worldwide, with Brazil being the main producer and consumer[4].

    Although most Passiflora species are American native, research on those species involved worldwide scientific groups. For example, due to their, actual and potential ecological and economic roles, in several world regions, such as China, projects for cropping and breeding Passiflora are being developed[5]. Medical researchers are determining the potential of Passiflora plant organs to recover physical and psychiatric human health[6,7].

    In Mexico, 91 Passiflora species, native and introduced, have been reported, indicating that, for this genus, this country is the fifth in worldwide diversity ranking[8]. Within Mexico, one of the areas with greater Passiflora diversity are the areas belonging to the southern states of Campeche, Chiapas, Yucatán, and Quintana Roo[9]. In Chiapas state there are, at least, two endemic species, P. pendens and P. tacanensis[8].

    The land area of those southern states is 215,047 km2, representing approximately 10% of the total Mexican territory. Nowadays, its current inhabitants belong to different ethnic groups and mestizo people[10]. Nevertheless, before Spanish irruption in Mexico, this area was inhabited by several groups belonging to ancient Mayan culture, including yucatecos in the states of the Yucatan Peninsula (Campeche, Yucatán, and Quintana Roo), and choles, tsetales, tsotsiles, tojolabanes, and lacandones in Chiapas state[11,12].

    As Mexico is one of the main land reserves for Passiflora plants, scientific efforts to claim further national studies on this plant genus must be performed. This review presents a list of the Passiflora species botanically recorded in four southern Mexican states. Then reports related to previous, actual, and potential uses for those species are briefly summarized. This review aims to point out the importance of the conservation of Passiflora genetic resources in southern Mexico.

    According to the herbaria MEXU[13], HERBANMEX[14], CICY[15], and CHAPA[16], thereafter confirmed in the specialized platform 'Plants of the word on line'[8], in the states under study, there are 55 Passiflora species (Table 1). Chiapas state accounts for 90% of those species, followed by Quintana Roo, Campeche, and Yucatán states[9].

    Table 1.  Passiflora species botanically registered in the states of Chiapas, Campeche, Quintana Roo, and Yucatán, Mexico; and their names in Spanish (S), Yucatec Maya (Y), Lacandón Maya (L), Tseltal Maya (T), and English (E).
    No. Species Location Name
    1 P. adenopoda DC. Chiapas (L): k'um sek; ucumin sek
    2 P. alata Curtis Chiapas (E): winged-stem passion flower
    3 P. ambigua Hemsl. Chiapas, Quintana Roo & Yucatán (S): granadilla de monte; ingo; jugito; jugo; (L): ch'um ak'
    4 P. apetala Killip Chiapas No information
    5 P. bicornis Mill. Campeche, Chiapas, Quintana Roo & Yucatán (S): ojo de luna; (Y): poch k' aak' ; kasu' uk; (E): wing-leaf passionfruit
    6 P. biflora Lam. Campeche, Chiapas, Quintana Roo & Yucatán (S): calzón de niño; bejuco de guaco; hoja de murcielago; (Y): poch aak'; (L): k'um sek (ah); (T): mayil poch;
    (E): twoflower passion-flower
    7 P. bryonioides Kunth Chiapas (S): granada cimarrona; (E): cupped passion flower
    8 P. capsularis L. Quintana Roo No information
    9 P. ciliata Aiton Campeche, Chiapas, Quintana Roo & Yucatán (S): maracuyá; sipolan; (Y): poch k' aak' ; poch kaki; xpoch aki; (E): fringed passion flower
    10 P. clypeophylla Mast. ex Don.Sm. Chiapas No information
    11 P. cobanensis Killip Campeche, Chiapas & Quintana Roo No information
    12 P. conzattiana Killip Campeche, Chiapas & Quintana Roo (S): hoja de vampiro
    13 P. dolichocarpa Killip Chiapas No information
    14 P. edulis Sims Campeche, Chiapas & Yucatán (S): maracuyá; flor de pasión; maracuyá morado;
    (Y): xton kee jil; (E): yellow passion fruit, purple passion fruit
    15 P. exsudans Zucc. Campeche (S): bolsa de gato; té de insomnio
    16 P. filipes Benth Chiapas (S): frijolillo; granadilla(E): slender passion flower
    17 P. foetida L. Campeche, Chiapas, Quintana Roo & Yucatán (S): amapola; maracuyá silvestre; granadillo; cinco llagas(Y): poch; túubok; poch' aak' ; poch' iil(E): stinking passion fruit; fetid passion flower; rambusa
    18 P. hahnii (E.Fourn.) Mast. Chiapas (S): granadilla chos
    19 P. helleri Peyr. Chiapas, Quintana Roo & Yucatán No information
    20 P. holosericea L. Chiapas No information
    21 P. itzensis (J.M.MacDougal) Port.-Ult. Chiapas, Quintana Roo & Yucatán (Y): maak xikin soots'
    22 P. jorullensis Kunth Chiapas (S): golondrina; tijerilla
    23 P. lancearia Mast. Chiapas No information
    24 P. ligularis Juss. Chiapas (S): granadilla; granada de moco; (E): sweet granadilla
    25 P. mayarum J.M.MacDougal Campeche, Chiapas & Quintana Roo (S): granadillo; (Y): toon ts' iimim; poch aak'; (E): wild passion flower
    26 P. membranacea Benth. Chiapas (S): granadilla; granada; (T): karanotozak; karanato rak'
    27 P. mexicana Juss. Chiapas No information
    28 P. morifolia Mast. Chiapas (E): woodland passion flower
    29 P. obovata Killip Campeche, Chiapas, Quintana Roo & Yucatán No information
    30 P. oerstedii Mast. Chiapas (S): granadilla chos
    31 P. ornithoura Mast. Campeche, Chiapas & Quintana Roo No information
    32 P. pallida L. Campeche, Chiapas, Quintana Roo & Yucatán (Y): sak aak' ; soots' aak' ; ts' unyajil
    33 P. pavonis Mast. Chiapas No information
    34 P. pedata L. Campeche, Quintana Roo & Yucatàn (Y): toom ts' iimin; tontotzimin
    35 P. pendens J.M.MacDougal Chiapas No information
    36 P. pilosa Ruiz & Pav. ex DC. Chiapas (S): granadilla; granada de zorro
    37 P. platyloba Killip Chiapas & Quintana Roo (S): granadilla de monte
    38 P. porphyretica Mast. Chiapas (T): schelchikin chinzak
    39 P. prolata Mast. Campeche, Chiapas & Quintana Roo (S): granadilla de monte
    40 P. quetzal J.M.MacDougal Chiapas No information
    41 P. rovirosae Killip Campeche, Chiapas & Quintana Roo No information
    42 P. sanctae-mariae J.M.MacDougal Chiapas No information
    43 P. seemannii Griseb Chiapas No information
    44 P. serratifolia L. Campeche, Chiapas, Quintana Roo & Yucatán (S): amapola; jujito amarillo; maracuyá de monte; pasionaria; granada de ratón; (Y): pooch aak' ; ya' ax pooch; (L): poochin; (E): broken ridge granadillo
    45 P. sexflora Juss. Chiapas & Campeche (S): granadilla chos;
    (T): schelchikinchinak; shel chikin chinzak; shel chikin
    46 P. sexocellata Schltdl. Campeche, Chiapas & Yucatàn (S) ala de murciélago; granada de ratón;
    (Y): xikin sots' ; xiik' sots'
    47 P. sicyoides Schltdl. & Cham. Chiapas (S) granadilla
    48 P. standleyi Killip Chiapas No information
    49 P. suberosa L. Campeche, Chiapas, Quintana Roo & Yucatán (S): granadilla roja; granadita de ratón; pata de pollo;
    (Y): kansel-ak; zal-kansel-ak; (I): cork-barked passion-flower, corky passion fruit
    50 P. sublanceolata (Killip) J.M.MacDougal Campeche, Quintana Roo & Yucatán (S) jujo; (Y): pooch k' aak'
    51 P. subpeltata Ortega Campeche & Chiapas (S) pasionaria, granadina, aretitos, granada de zorra, jujo
    52 P. tacanensis Port.-Utl. Chiapas No information
    53 P. tarminiana Coppens & V.E.Barney Chiapas No information
    54 P. xiikzodz J.M.MacDougal Campeche, Chiapas, Quintana Roo & Yucatán (Y): maak xikin soots'
    55 P. yucatanensis Killip ex Standl. Campeche, Quintana Roo & Yucatán (S): flor de la pasión de Yucatán; (E): Yucatan passion flower
    References[5,6,8,9,1318].
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    Chiapas state presents five biogeographical provinces related to a specific natural area in relation to its endemic biota. Those five provinces are, the 'Gulf of Mexico lowland', 'Chiapas central plateau', 'Chiapas central depression', 'Madre mountain range', and 'coastal lowland'. In contrast, within the Campeche state area, there are two biographical provinces, the 'Gulf of Mexico lowland' and the 'Yucatán lowland'. Whereas Yucatán and Quintana Roo states belong only to the province named 'Yucatán lowland'[19]. Thus, the presence of different biogeographical provinces, implying different climates and ecological conditions, might influence Passiflora diversity. For example, in Mexico, Chiapas state is known to be the second state with a relatively high total plant diversity, with over 10,000 plant species[20].

    For Chiapas state, there are botanical reports of Passiflora in 65 of the 126 municipalities, with a greater presence in Ocosingo (19 species), Unión Juárez (nine species), and Palenque (eight species). Including the four states under study, the municipality of Othón P. Blanco, Quintana Roo state (11 species), follows Ococingo, and then, the list continues with Calakmul, Campeche State (11 species). For Yucatán state, a greater Passiflora presence has been reported in Progreso (five species) (Fig. 1).

    Figure 1.  Municipalities within Peninsula de Yucatán and Chiapas, Mexico, with greater botanical reports of Passiflora species. Chiapas (yellow) [Ococingo (19), Unión Juárez (9), and Palenque (8)], Campeche (red) [Calakmul (11), Holpechén (6), Campeche (5), and Champotón (5)], Yucatán (black) [Progreso (5)], and Quintana Roo (purple) [Othón P. Blanco (11), Felipe Carrillo Puerto (8), and José María Morelos (5)]. Four Passiflora species illustrate this genus diversity. Data of present work were marked on a map sourced from Google Earth.

    The number of Passiflora species recorded in Ocosingo is greater than the number of Passiflora species reported in each of the other 18 states in Mexico[9]. Additionally, Unión Juárez must be valorized for its Passiflora richness, as the municipality area is only 62 km2[10].

    Passiflora species grow mainly in family orchards and jungle systems[12,21]; the latter system is very sensitive to overexploitation of natural resources, pollution, and climatic change. Moreover, it is very responsive to demographic changes, public policies, and local technological projects[22].

    To our knowledge, there are no reports of the use of Passiflora plants by ancient Mayan culture. However, ethnobotanical reports, written in the last three decades, indicate that in the Lacandón forest, native people eat the fruits of 'ch'um ak'' (P. ambigua), 'ch'ink ak'il' (Passiflora sp.) 'poochin' (P. serratifolia) and P. hahnii[12,13]. A recent review confirmed the consumption of P. ambigua, P. bicornis, P. ciliata, P. foetida, P. hahnii, P. ligularis, P. mayarum, P. serratifolia, and P. yucatensis fruits in communities of Chiapas and the Yucatan Peninsula[23].

    In Yucatán state, the P. ciliata plant is used to treat hysteria, sleeplessness, and child convulsion; local people assign this species narcotic and sedative properties[24]. In the Chiapas High Valleys, P. membranacea liana is used as a rope to tie tools or help build rudimentary houses[21].

    In the municipality of Solidaridad, Quintana Roo State, the staff of the butterfly pavilion of a theme park, crop at least two Passiflora species, one allegedly to be P. lobata ('pata de gallo' in Spanish), to raise butterfly larvae. The information within the park, mentions that they raise the butterflies Agraulis vanillae, Dryas iulias, Heliconius erato, and H. charithonia. Scientific literature supports the preference of butterfly larvae for P. lobata[25].

    For centuries, some effects on the human body have been assigned to Passiflora plants. Moreover, in the Spanish language, the name of passion fruit was misunderstood, and many people have given aphrodisiac properties to Passiflora species, instead of relating its name to the passion of Christ[1]. Moreover, in plants of this genus, several molecules with spasmolytic, sedative, anxiolytic, and blood pressure modulation properties have been identified. One of those molecules is passicol, which has antibacterial properties. P. foetida leaf extracts reduce the growth of Pseudomonas putida, Vidrio cholerae, Shigella flexneri, and Streptococcus pyogenes, supporting the use of this plant in ethnopharmacology to treat fiber, diarrhea, stomach and throat pains, and ear and skin infections[26].

    It has been suggested that the anthocyanin present in the peel of P. biflora might be used as an additive to increase color and antioxidant capacity in some human foods[27]. Additionally, pectin can be extracted from the Passiflora peel for human consumption[28], and it has been proposed to transform peel into biofuels[29]. As Brazil is a high yellow passion fruit producer, it has been proposed to produce passion fruit seed oil there. The oil might be used in human foods or transformed into creams, shampoos, and pharmacology products[30]. In addition, among the seed components, there are stilbenes, which are excellent antioxidants, enhance human skin conditions, and present hypoglycemic properties[31].

    In the Yucatan Peninsula, Passiflora is among the top five plant genera with relatively high diversity[17]. This richness might be used to breed, aiming for genotypes producing high-quality fruits and suitable for cropping in new areas[5,32]. Nevertheless, land use change represents one of the greatest risks to conserving actual biodiversity; this factor also contributes to increasing the rate of climatic change and affects ecosystem sustainability[33].

    Quintana Roo state is one of the main tourist region's in Mexico, Cancun resort area is located there, and further luxury resorts are still planned. Mexican environmental law protects approximately 30% of the land of the municipality of Othón P. Blanco, Quintana Roo state[34]; and this municipality started policy programs for sustainable bay management, keeping its vegetation, including several medicinal plants[35]. In this sense, recently, the Mexican government involved some institutes in flora conservation. In the municipality of Solidaridad, Quintana Roo state, the Botanical Garden 'Dr. Alfredo Barrera Marín' belonging to the 'Centro de Investigaciones de Quintana Roo' is the repository of the flora native of the section North 5 of the project Maya Railway.

    In general, in the four states under study herein, there are important archeological and touristic venues; thus, Passiflora conservation in southern Mexico might involve ethno-tourism, ecotourism, and other local developmental projects. Moreover, in the Yucatan Peninsula and Chiapas there are almost 17 areas named Nature Reserves. They are: 'Pantanos de Centla', 'Río Celestum', 'Río Lagartos', 'Sian Ka'an' 'Chinchorro', 'Caribe Mexicano', 'Tiburón ballena', 'El triunfo', 'La Encrucijada', 'La Sepultura', 'Lacan tún', 'Montes azules', 'Selva El Ocote', 'Volcán Tacaná', 'Calakmul', 'Balam ku', and 'Los Peténes'. Therefore, according to UNESCO, in nature reserves, effective fauna and flora protection policies might be observed[36].

    The role of Passiflora plant species in conserving local fauna, and, by a consequence, help to keep the ecosystem balance, must be carefully understood. Several Passiflora species included in Table 1 have been reported to be good feed sources for animals. For example, P. biflora may play a role in conserving bats in the Lacandón forest[9]. For Passiflora species being bat-pollinated, it has been observed that their flowers are well adapted to bat behavior, as their flowers secrete nectar at night[37]. Moreover, it has been reported that some years after introducing Passiflora plants, the population of butterflies and bees was increased[9]. Some studies have revealed that P. suberosa is a good feed source for A. vanillae maculosa larvae, although less preferred by D. iulia caterpillar, who prefers leaves of P. misera[38,39].

    Although tropical forest regeneration is possible, the predicted growth of urban areas is a risk factor[33] in reducing Passiflora diversity. On the other hand, some researchers have suggested that rural families contribute strongly to maintaining plant species[40]. Thus, reducing the poverty factor might be included in national, state, and municipality politics to recognize the importance of native and original communities in conserving plant genetic resources. For example, within the three municipalities with the greatest presence of Passiflora species, only Othón P. Blanco has less than 45% of its population living in poverty, whereas over 80% of the populations of Ocosingo and Calakmul live in poverty. In five of the six municipalities with a greater presence of Passiflora, the human population living in poverty is greater than 70%[41].

    Although some countries offer payments to conserve plant genetic resources, they are limited to plant species presenting economic importance[42]. Thus, to involve local people in plant genetic conservation, projects aimed at sustainability, environment conservation, prosperity, and human welfare must be offered. The municipality, state, and national governments must establish laws and regulations to save jungles and mangroves. Further efforts to keep flora and fauna, in this case Passiflora species, in the areas with a higher presence of this genus, are expected to keep its holistic value and diversity.

    The high diversity of Passiflora plants in Chiapas state seems to be related to the presence of five biographical provinces: 'Gulf of Mexico lowland', 'Chiapas central plateau', 'Chiapas central depression', 'Madre mountain range', and 'coastal lowland'. Within Chiapas state, Ococingo is the municipality with the highest Passiflora diversity.

    Although there are no reports of the use of Passiflora in ancient Maya culture living in Chiapas, Campeche, Yucatán, or Quintana Roo states, the actual use of Passiflora suggests inherited knowledge. On the other hand, the agro-industrial and pharmacological potential of this plant genus might help promote sustainable regional development. The rescue of traditional fruit species and their ancient knowledge might enhance the local economy and maintain ecological balance.

  • The authors confirm contribution to the paper as follows: study conception and design: Franco-Mora O; data collection: Franco-Mora O, Moreno-Jiménez A; analysis and interpretation of results: Franco-Mora O, Sánchez-Pale JR; draft manuscript preparation: Franco-Mora O, Castañeda-Vildózola Á. All authors reviewed the results and approved the final version of the manuscript.

  • The herbarium MEXU, HERBANMEX, and CICY offers free access to their on line database; they are cited in the References section[1315]. Data from herbaria CHAPA (16) is available at the Institute.

  • The herbaria exemplars, consulted herein, represent the work of several botanists. The picture of Passiflora ciliata was kindly donated by Prof. Elia Ballesteros-Rodríguez (CICY, Yucatán, Mexico).

  • The authors declare that they have no conflict of interest.

  • Supplemental Table S1 Primers used in this study.
    Supplemental Fig. S1 Preparation of crude extract solutions for application.
    Supplemental Fig. S2 Scutellaria baicalensis Georgi extracts and baicalin affect the aboveground and underground tissue fresh weight of tomato seedlings.
    Supplemental Fig. S3 The stomatal conductance and transpiration rate of tomato seedling leaves in response to Scutellaria baicalensis Georgi extracts and baicalin treatments.
    Supplemental Fig. S4 The endoreduplication level in tomato stem cells (A) and leaf cells (B) after Scutellaria baicalensis Georgi extracts treatments.
  • [1]

    Wang J, Qin L, Cheng J, Shang C, Li B, et al. 2022. Suitable chemical fertilizer reduction mitigates the water footprint of maize production: evidence from Northeast China. Environmental Science and Pollution Research 29:22589−601

    doi: 10.1007/s11356-021-17336-2

    CrossRef   Google Scholar

    [2]

    Rahimi A, Mohammadi MM, Moghaddam SS, Heydarzadeh S, Gitari H. 2022. Effects of stress modifier biostimulants on vegetative growth, nutrients, and antioxidants contents of garden thyme (Thymus vulgaris L.) under water deficit conditions. Journal of Plant Growth Regulation 41:2059–72

    doi: 10.1007/s00344-022-10604-6

    CrossRef   Google Scholar

    [3]

    Castiglione AM, Mannino G, Contartese V, Bertea CM, Ertani A. 2021. Microbial biostimulants as response to modern agriculture needs: composition, role and application of these innovative products. Plants 10:1533

    doi: 10.3390/plants10081533

    CrossRef   Google Scholar

    [4]

    Aguirre E, Leménager D, Bacaicoa E, Fuentes M, Baigorri R, et al. 2009. The root application of a purified leonardite humic acid modifies the transcriptional regulation of the main physiological root responses to Fe deficiency in Fe-sufficient cucumber plants (vol 47, pg 215, 2008). Plant Physiology and Biochemistry 47:966

    doi: 10.1016/j.plaphy.2009.06.004

    CrossRef   Google Scholar

    [5]

    Torabian S, Farhangi-Abriz S, Rathjen J. 2018. Biochar and lignite affect H+-ATPase and H+-PPase activities in root tonoplast and nutrient contents of mung bean under salt stress. Plant Physiology and Biochemistry 129:141−49

    doi: 10.1016/j.plaphy.2018.05.030

    CrossRef   Google Scholar

    [6]

    Wang M, Chen Y, Zhang R, Wang W, Zhao X, et al. 2015. Effects of chitosan oligosaccharides on the yield components and production quality of different wheat cultivars (Triticum aestivum L.) in Northwest China. Field Crops Research 172:11−20

    doi: 10.1016/j.fcr.2014.12.007

    CrossRef   Google Scholar

    [7]

    Brown P, Saa S. 2015. Biostimulants in agriculture. Frontiers in Plant Science 6:671

    doi: 10.3389/fpls.2015.00671

    CrossRef   Google Scholar

    [8]

    Köhl J, Kolnaar R, Ravensberg WJ. 2019. Mode of action of microbial biological control agents against plant diseases: relevance beyond efficacy. Frontiers in Plant Science 10:845

    doi: 10.3389/fpls.2019.00845

    CrossRef   Google Scholar

    [9]

    Zhu H, Wang X, Wang X, Pan G, Zhu Y, et al. 2021. The toxicity and safety of Chinese medicine from the bench to the bedside. Journal of Herbal Medicine 28:100450

    doi: 10.1016/j.hermed.2021.100450

    CrossRef   Google Scholar

    [10]

    Yazaki K, Matsuoka H, Shimomura K, Bechthold A, Sato F. 2001. A novel dark-inducible protein, LeDI-2, and its involvement in root-specific secondary metabolism in Lithospermum erythrorhizon. Plant Physiology 125:1831−41

    doi: 10.1104/pp.125.4.1831

    CrossRef   Google Scholar

    [11]

    Chen L, Li J, Zhu Y, Zhao T, Guo L, et al. 2022. Weed suppression and molecular mechanisms of isochlorogenic acid A isolated from Artemisia argyi extract via an activity-guided method. Journal of Agricultural and Food Chemistry 70:1494−506

    doi: 10.1021/acs.jafc.1c06417

    CrossRef   Google Scholar

    [12]

    Chen L, Li J, Zhu Y, Guo L, Ji R, et al. 2021. Caffeic acid, an allelochemical in Artemisia argyi, inhibits weed growth via suppression of mitogen-activated protein kinase signaling pathway and the biosynthesis of gibberellin and phytoalexin. Frontiers in Plant Science 12:802198

    doi: 10.3389/fpls.2021.802198

    CrossRef   Google Scholar

    [13]

    Li J, Chen L, Chen Q, Miao Y, Peng Z, et al. 2021. Allelopathic effect of Artemisia argyi on the germination and growth of various weeds. Scientific Reports 11:4303

    doi: 10.1038/s41598-021-83752-6

    CrossRef   Google Scholar

    [14]

    Zhang M, Cao B, Che L, Liu L, Su Y, et al. 2023. Post-harvest freezing injury reduces exterior quality of medicinal material and promotes transformation from glycosides to aglycones in Scutellaria baicalensis. Industrial Crops and Products 201:116915

    doi: 10.1016/j.indcrop.2023.116915

    CrossRef   Google Scholar

    [15]

    Lu Y, Cao B, Su Y, Yang J, Xue Y, et al. 2022. Inter-specific differences of medicinal bioactive products are correlated with differential expressions of key enzyme genes in Scutellaria baicalensis and Scutellaria viscidula. Industrial Crops and Products 189:115758

    doi: 10.1016/j.indcrop.2022.115758

    CrossRef   Google Scholar

    [16]

    Liao H, Ye J, Gao L, Liu Y. 2021. The main bioactive compounds of Scutellaria baicalensis Georgi. for alleviation of inflammatory cytokines: a comprehensive review. Biomedicine & Pharmacotherapy 133:110917

    doi: 10.1016/j.biopha.2020.110917

    CrossRef   Google Scholar

    [17]

    Da X, Nishiyama Y, Tie D, Hein KZ, Yamamoto O, et al. 2019. Antifungal activity and mechanism of action of Ou-gon (Scutellaria root extract) components against pathogenic fungi. Scientific Reports 9:1683

    doi: 10.1038/s41598-019-38916-w

    CrossRef   Google Scholar

    [18]

    Rakkammal K, Maharajan T, Ceasar SA, Ramesh M. 2023. Biostimulants and their role in improving plant growth under drought and salinity. Cereal Research Communications 51:61−74

    doi: 10.1007/s42976-022-00299-6

    CrossRef   Google Scholar

    [19]

    Xu C, Ma M, Xin J, Li J, Ma F, et al. 2024. The active compound in Rheum officinale Baill, aloe-emodin promotes tomato seedling growth. Plant Growth Regulation 102:213−26

    doi: 10.1007/s10725-023-00995-1

    CrossRef   Google Scholar

    [20]

    Liu Y, Roof S, Ye Z, Barry C, van Tuinen A, et al. 2004. Manipulation of light signal transduction as a means of modifying fruit nutritional quality in tomato. Proceedings of the National Academy of Sciences of the United States of America 101:9897−902

    doi: 10.1073/pnas.0400935101

    CrossRef   Google Scholar

    [21]

    Barow M, Meister A. 2003. Endopolyploidy in seed plants is differently correlated to systematics, organ, life strategy and genome size. Plant, Cell & Environment 26:571−84

    doi: 10.1046/j.1365-3040.2003.00988.x

    CrossRef   Google Scholar

    [22]

    Liu G, Yu H, Yuan L, Li C, Ye J, et al. 2021. SlRCM1, which encodes tomato Lutescent1, is required for chlorophyll synthesis and chloroplast development in fruits. Horticulture Research 8:128

    doi: 10.1038/s41438-021-00563-6

    CrossRef   Google Scholar

    [23]

    Qu L, Wei Z, Chen H, Liu T, Liao K, et al. 2021. Plant casein kinases phosphorylate and destabilize a cyclin-dependent kinase inhibitor to promote cell division. Plant Physiology 187:917−30

    doi: 10.1093/plphys/kiab284

    CrossRef   Google Scholar

    [24]

    Zhang Q, Ma C, Wang X, Ma Q, Fan S, et al. 2021. Genome-wide identification of the light-harvesting chlorophyll a/b binding (Lhc) family in Gossypium hirsutum reveals the influence of GhLhcb2.3 on chlorophyll a synthesis. Plant Biology 23:831−42

    doi: 10.1111/plb.13294

    CrossRef   Google Scholar

    [25]

    Fukayama H, Mizumoto A, Ueguchi C, Katsunuma J, Morita R, et al. 2018. Expression level of Rubisco activase negatively correlates with Rubisco content in transgenic rice. Photosynthesis Research 137:465−74

    doi: 10.1007/s11120-018-0525-9

    CrossRef   Google Scholar

    [26]

    Suzuki S, Endoh R, Manabe RI, Ohkuma M, Hirakawa Y. 2018. Multiple losses of photosynthesis and convergent reductive genome evolution in the colourless green algae Prototheca. Scientific Reports 8:940

    doi: 10.1038/s41598-017-18378-8

    CrossRef   Google Scholar

    [27]

    Song S, Liu G, Ma F, Bao Z. 2022. Brassinazole represses tomato hypocotyl elongation via inhibition of cell division. Plant Growth Regulation 96:463−72

    doi: 10.1007/s10725-022-00798-w

    CrossRef   Google Scholar

    [28]

    Zhang Y, Yin H, Zhao X, Wang W, Du Y, et al. 2014. The promoting effects of alginate oligosaccharides on root development in Oryza sativa L. mediated by auxin signaling. Carbohydrate Polymers 113:446−54

    doi: 10.1016/j.carbpol.2014.06.079

    CrossRef   Google Scholar

    [29]

    Liu H, Zhang Y, Yin H, Wang W, Zhao X, et al. 2013. Alginate oligosaccharides enhanced Triticum aestivum L. tolerance to drought stress. Plant Physiology and Biochemistry 62:33−40

    doi: 10.1016/j.plaphy.2012.10.012

    CrossRef   Google Scholar

    [30]

    Zhang Y, Liu H, Yin H, Wang W, Zhao X, et al. 2013. Nitric oxide mediates alginate oligosaccharides-induced root development in wheat (Triticum aestivum L.). Plant Physiology and Biochemistry 71:49−56

    doi: 10.1016/j.plaphy.2013.06.023

    CrossRef   Google Scholar

    [31]

    Panfili I, Bartucca ML, Marrollo G, Povero G, Del Buono D. 2019. Correction to application of a plant biostimulant to improve maize (Zea mays) tolerance to metolachlor. Journal of Agricultural and Food Chemistry 67:14005

    doi: 10.1021/acs.jafc.9b07118

    CrossRef   Google Scholar

    [32]

    Bi D, Yang X, Lu J, Xu X. 2022. Preparation and potential applications of alginate oligosaccharides. Critical Reviews in Food Science and Nutrition 63:10130−47

    doi: 10.1080/10408398.2022.2067832

    CrossRef   Google Scholar

    [33]

    Liu M, Yang Q, Hua Q, Liu J, He W, et al. 2021. Chinese medicinal herbs for idiopathic membranous nephropathy in adults with nephrotic syndrome: a systematic review of effectiveness and safety. Medicine 100:e27953

    doi: 10.1097/MD.0000000000027953

    CrossRef   Google Scholar

    [34]

    Niu C, Wang G, Sui J, Liu G, Ma F, et al. 2022. Biostimulants alleviate temperature stress in tomato seedlings. Scientia Horticulturae 293:110712

    doi: 10.1016/j.scienta.2021.110712

    CrossRef   Google Scholar

    [35]

    Ebinezer LB, Franchin C, Trentin AR, Carletti P, Trevisan S, et al. 2020. Quantitative proteomics of maize roots treated with a protein hydrolysate: a comparative study with transcriptomics highlights the molecular mechanisms responsive to biostimulants. Journal of Agricultural and Food Chemistry 68:7541−53

    doi: 10.1021/acs.jafc.0c01593

    CrossRef   Google Scholar

    [36]

    Lee HJ, Lee JH, Lee SG, An S, Lee HS, et al. 2019. Foliar application of biostimulants affects physiological responses and improves heat stress tolerance in Kimchi cabbage. Horticulture, Environment, and Biotechnology 60:841−51

    doi: 10.1007/s13580-019-00193-x

    CrossRef   Google Scholar

    [37]

    Fernandes Â, Chaski C, Pereira C, Kostić M, Rouphael Y, et al. 2022. Water Stress alleviation effects of biostimulants on greenhouse-grown tomato fruit. Horticulturae 8:645

    doi: 10.3390/horticulturae8070645

    CrossRef   Google Scholar

    [38]

    Cameron A, Sarojini V. 2014. Pseudomonas syringae pv. actinidiae: chemical control, resistance mechanisms and possible alternatives. Plant Pathology 63:1−11

    doi: 10.1111/ppa.12066

    CrossRef   Google Scholar

    [39]

    Xu Y, Wieloch T, Kaste JAM, Shachar-Hill Y, Sharkey TD. 2022. Reimport of carbon from cytosolic and vacuolar sugar pools into the Calvin-Benson cycle explains photosynthesis labeling anomalies. Proceedings of the National Academy of Sciences of the United States of America 119:e2121531119

    doi: 10.1073/pnas.2121531119

    CrossRef   Google Scholar

    [40]

    Sukkasam N, Incharoensakdi A, Monshupanee T. 2022. Disruption of hydrogen gas synthesis enhances the cellular levels of NAD(P)H, glycogen, poly(3-hydroxybutyrate) and photosynthetic pigments under specific nutrient condition(s) in cyanobacterium Synechocystis sp. PCC 6803. Plant and Cell Physiology 63: 135−47

    doi: 10.1093/pcp/pcab156

    CrossRef   Google Scholar

    [41]

    Salas-González I, Reyt G, Flis P, Custódio V, Gopaulchan D, et al. 2021. Coordination between microbiota and root endodermis supports plant mineral nutrient homeostasis. Science 371:eabd0695

    doi: 10.1126/science.abd0695

    CrossRef   Google Scholar

    [42]

    Wu J, Zhao H, Wang X. 2022. Soil microbes influence nitrogen limitation on plant biomass in alpine steppe in North Tibet. Plant and Soil 474:395−409

    doi: 10.1007/s11104-022-05343-2

    CrossRef   Google Scholar

    [43]

    Furbank RT, Quick WP, Sirault XRR. 2015. Improving photosynthesis and yield potential in cereal crops by targeted genetic manipulation: Prospects, progress and challenges. Field Crops Research 182:19−29

    doi: 10.1016/j.fcr.2015.04.009

    CrossRef   Google Scholar

    [44]

    Tamirisa S, Vudem DR, Khareedu VR. 2017. A cyclin dependent kinase regulatory subunit (CKS) Gene of pigeonpea imparts abiotic stress tolerance and regulates plant growth and development in Arabidopsis. Frontiers in Plant Science 8:165

    doi: 10.3389/fpls.2017.00165

    CrossRef   Google Scholar

    [45]

    Chan Z. 2012. Expression profiling of ABA pathway transcripts indicates crosstalk between abiotic and biotic stress responses in Arabidopsis. Genomics 100:110−15

    doi: 10.1016/j.ygeno.2012.06.004

    CrossRef   Google Scholar

    [46]

    Kulkarni MG, Stirk WA, Southway C, Papenfus HB, Swart PA, et al. 2013. Plant growth regulators enhance gold uptake in Brassica juncea. International Journal of Phytoremediation 15:117−26

    doi: 10.1080/15226514.2012.683207

    CrossRef   Google Scholar

    [47]

    Xiao T, Boada R, Marini C, Llugany M, Valiente M. 2020. Influence of a plant biostimulant on the uptake, distribution and speciation of Se in Se-enriched wheat (Triticum aestivum L. cv. Pinzón). Plant and Soil 455:409−23

    doi: 10.1007/s11104-020-04686-y

    CrossRef   Google Scholar

    [48]

    Chennappa G, Sreenivasa MY, Nagaraja H. 2018. Azotobacter salinestris: a novel pesticide-degrading and prominent biocontrol PGPR bacteria. In Microorganisms for Green Revolution, eds. Panpatte D, Jhala Y, Shelat H, Vyas R. Vol. 7. Singapore: Springer. pp. 23−43. https://doi.org/10.1007/978-981-10-7146-1_2

    [49]

    Jing J, Zhang S, Yuan L, Li Y, Zhang Y, et al. 2022. Synergistic effects of humic acid and phosphate fertilizer facilitate root proliferation and phosphorus uptake in low-fertility soil. Plant and Soil 478:491−503

    doi: 10.1007/s11104-022-05486-2

    CrossRef   Google Scholar

  • Cite this article

    Liu G, Xin J, Li C, Ma M, Fan J, et al. 2024. Scutellaria baicalensis Georgi extracts and its active compound baicalin promote tomato seedling growth. Vegetable Research 4: e023 doi: 10.48130/vegres-0024-0023
    Liu G, Xin J, Li C, Ma M, Fan J, et al. 2024. Scutellaria baicalensis Georgi extracts and its active compound baicalin promote tomato seedling growth. Vegetable Research 4: e023 doi: 10.48130/vegres-0024-0023

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Scutellaria baicalensis Georgi extracts and its active compound baicalin promote tomato seedling growth

Vegetable Research  4 Article number: e023  (2024)  |  Cite this article

Abstract: Excessive use of chemical fertilizers and pesticides causes pollution of soil, water, and the atmosphere. Biostimulants are derived from natural sources, which can help plants absorb nutrients and promote plant development. Chinese herbal medicine extracts are enriched with bioactive compounds and therefore hold great potential for developing novel biostimulants. In this study, the predominant active compound, baicalin, was detected in Scutellaria baicalensis Georgi ('Huangqin' in Chinese) extracts via LC-MS/MS. To explore their effects, we used three different methods to treat tomato seedlings with Scutellaria baicalensis Georgi (S. baicalensis) extracts or baicalin, including foliar spraying (S), root irrigation (R), and the combination of foliar spraying and root irrigation (SR). Both S. baicalensis crude extracts and commercial baicalin promoted stem and root development, enhanced the photosynthetic capacity, and increased tomato seeding biomass, eventually making tomato seedlings grow vigorously. Clustering analysis and principal component analysis showed that S. baicalensis extracts and baicalin had very similar effects and showed the best effects in SR treatment. S. baicalensis extracts and its active compound baicalin could promote tomato seedling growth, suggesting that S. baicalensis is a potential source of biostimulants.

    • Using chemical pesticides and fertilizers has promoted the development of modern agriculture. However, the irrational use of pesticides and fertilizers not only leads to the imbalance of soil nutrients, low yield of crops, poor quality and reduced stress resistance, but also causes environmental pollution[1]. Biostimulants can boost plant growth, improve crop quality, and alleviate abiotic stress, which mainly includes humic acids, seaweed extracts, amino acids, chitin, chitosan, and microbial agents[2]. Biostimulants can improve the utilization rate of fertilizers or enhance the efficacy of pesticides, and regulate the damage caused by the unreasonable use of fertilizers and pesticides to the soil microenvironment, thereby improving the growth of crops[3,4]. For instance, humic acid promotes plant growth via regulating the activity of H+-ATPase to enhance the absorption and transport of nutrients in roots[5]. Seaweed extracts increase plant photosynthetic capacity by enhancing phosphatase and nitrate reductase accumulation. Chitooligosaccharides increase the content of secondary metabolites related to low-temperature resistance in wheat[6]. Microbial agents increase crop yield by enhancing respiration and increasing microbial biomass in soil[7,8]. Biostimulants have diverse origins and distinct functions in regulating crop growth and development.

      Chinese herbal medicines are taken from nature and have the advantages of being green, having no residue, and having low toxicity. Chinese medicinal herbs have only been studied in detail for fungal inhibition, medical treatment, and addition to livestock feeds[9]. Previous studies have shown that secondary metabolites derived from Chinese medicine herbs play an important role in regulating plant growth and development[10]. Artemisia argyi extracts significantly inhibit the stem and root length of Setaria viridis and Portulaca oleracea, thereby reducing their biomass[11]. Caffeic acid is an important allelochemical extracted from Artemisia argyi, which down-regulates multiple genes involved in gibberellin, phytoalexin biosynthesis, and mitogen-activated protein kinase signaling pathways to inhibit weed growth[12]. The allelopathy of Artemisia argyi extracts is manifested in inhibiting seed germination and seedling growth of Chinese cabbage, lettuce, and rice[13]. As traditional Chinese herbal medicine, Scutellaria baicalensis Georgi ('Huangqin' in Chinese) has a wide range of pharmacological effects and high medicinal value in clinical practice. Freezing injury reduced the content of baicalin, wogonoside, and scutellarin and increased the content of baicalein, wogonin, and scutellarein in S. baicalensis[14]. FNSII, GUS, and UBGAT as key enzyme genes play important roles in baicalin biosynthesis[15]. Its root is an important medicinal organ of S. baicalensis[16]. Baicalin, belonging to flavonoids and is an important bioactive component in S. baicalensis, which can effectively inhibit the reproduction and growth of Aspergillus niger, Aspergillus oryzae, Aspergillus fumigatus, Candida albicans, Candida glabrata, and Candida tropicalis[17]. To explore new ways to promote crop growth via the application of new biostimulants, a comprehensive study on the regulatory effects of herbal extracts on crop growth and quality was carried out to provide theoretical and data support for practical production.

      Biostimulants have been widely applied in crops to increase production and income[18]. However, the study of active compounds in S. baicalensis extracts as biological stimulants in regulating plant growth and development has not been reported. In the present study, the LC-MS/MS method was first utilized to analyze the crude extracts of S. baicalensis and it was verified that baicalin was the major active compound in the S. baicalensis extract. Next the S. baicalensis extracts and the actual standard of baicalin were applied to tomato seedlings at the vegetative growth stage via spraying foliar (S), root irrigation (R) or spraying foliar and root irrigation (SR) modes. Both S. baicalensis extracts and baicalin had very similar effects in promoting seeding growth and leaf photosynthetic efficiency. Overall, S. baicalensis extracts and baicalin were more effective on tomato seedings growth and development.

    • Seeds of tomato (Solanum lycopersium L.) cultivar Ailsa Craig germinated on nutrient agar medium for three days in incubator at 28 °C. When the radicle of the seed began to grow, these seeds were sown in nutrient substrates that contained vermiculite, perlite, and soil (1:1:1, v/v/v) under normal conditions. At the two-leaf stage, the uniform seedlings were selected and transferred to the nursery pot (10 cm × 10 cm × 10 cm, one plant per pot), and Hoagland's nutrient solution was used to water them every 3 d. All seedlings were cultured in a light incubator. The incubator conditions were set to a temperature of 25 °C, and a light-dark cycle of (16 h light:8 h dark), and a light intensity of 100 μmol/m2/s.

    • The dry slices of S. baicalensis roots were purchased from Taobao web (www.taobao.com). The S. baicalensis roots were placed in an oven at 50−60 °C for 2−3 h with forced-air drying. In the process of forced-air drying, the wind speed is 2.0−2.5 m/s. For experimentation of S. baicalensis crude extracts, dry slices of S. baicalensis were first washed with flowing water and then immersed in water for 1 h mixing every 10 min under normal lighting conditions. The slices of S. baicalensis were boiled in water at 100 °C for 1 h to obtain the active compounds. According to our pre-experiment, the primitive extracts of S. baicalensis were cooled down and diluted to a working concentration (6 g dry S. baicalensis slices per liter) for subsequent treatment experiments. We utilized the same batch of S. baicalensis dry slices, and the concentration of baicalin was determined using LC-MS/MS. The amount of 1 g S. baicalensis dry slices contained about 7.7 mg baicalin. The baicalin purchased from Shanghai Yuanye Bio-Technology Co., Ltd (Shanghai, China) was dissolved in ultrapure water and diluted to 0.046 g/L. The six uniform tomato plants with four leaves were tested for each experiment. In this experiment, four treatments (application modes) were conducted as follows: (1) S: spraying S. baicalensis extracts or baicalin on leaves and irrigating water on roots. (2) R: spraying water on leaves and irrigating S. baicalensis extracts or baicalin on roots. (3) SR: spraying S. baicalensis extracts or baicalin on leaves and irrigating S. baicalensis extracts or baicalin on roots. (4) CK represents spraying water on leaves and irrigating water on roots (Fig. 1). Plastic sprinklers with 1 cm diameter round nozzles were used for the spraying. Plants were treated once every 3 d, a total of five treatments. Then, the physiological indexes of the treated plants were measured. Each treatment included six biological replicates.

      Figure 1. 

      Four treatment modes were performed as follows: (1) CK: spraying water on leaves and irrigating water on roots. (2) S: spraying S. baicalensis extracts or baicalin on leaves and irrigating water on roots. (3) R: spraying water on leaves and irrigating S. baicalensis extracts or baicalin on roots. (4) SR: spraying S. baicalensis extracts or baicalin on leaves and irrigating S. baicalensis extracts or baicalin on roots. In this study, CK was the control group.

    • The major active compound baicalin in S. baicalensis crude extracts was determined by LC-MS/MS (LCMS-8050) using the actual standard of baicalin (cas#: 21967-41-9; purity: 90%) (Xu et al.[19]). Based on the standard curve generated for baicalin via LC-MS/MS, the concentration of baicalin in the original S. baicalensis extract solution was calculated to be 0.77 g/L (Supplemental Fig. S1).

    • The tomato plants with treatments were photographed. ImageJ software was used to determine plant height, stem diameter, and leaflet area after treatments. The length from the surface of the substrate to the top of the stem was used as the plant height. The average plant height was obtained from six individuals. Leaf area was measured from individual leaves. The fourth fully developed leaves were quick-frozen with liquid nitrogen and then ground into a fine powder. Then, photosynthetic pigments were extracted from 100 mg powder with 80% acetone[20]. Six plants of each treatment were analyzed.

    • The net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (E) of the fourth leaf of tomato seedlings with treatments were measured on a sunny day from 9:00 a.m. to 12:00 noon using the CIRAS-3 Portable Photosynthesis System. The maximum photochemical efficiency (Fv/Fm) and actual quantum efficiency (PSII) of tomato leaves after dark treatment was measured for 30 min using an FMS-2 portable fluorometer. Six plants of each treatment were analyzed.

    • The WINRHIZO multi-parameter plant root analysis system was used to scan the roots of tomato seedlings after S. baicalensis extracts and baicalin treatment then the total root length, surface area, volume, diameter, number of nodes, and number of root tips were counted. Six plants of each treatment were analyzed.

    • The aboveground and underground tissues were separated from the plants, and then the fresh weight (FW) of tissues was quantified using balance. The aboveground and underground tissues were placed in envelopes and then dried at 105 °C for 0.5 h, cooled to 60 °C and dried for an additional 2 d in an oven.

    • Leaf and stem tissues of tomato seedlings were used for extracting the nucleus. About 50 mg of fresh tissue was collected, added with 1 mL cell lysis buffer, and then chopped with a blade. The buffer contained 10 mM MgSO4·7H2O, 50 mM KCl, 5 mM 4-Hydroxyethylpiperazine ethane sulfonic acid (HEPES), 2.5% Triton X-1006, and 5 mM Dithiothreitol (DTT). The nuclei were stained with propidium iodide (PI) at a concentration of 50 μg/mL. The cell cycle was determined and calculated by BD flow cytometry (BD Biosciences, San Jose, California, USA) and FlowJo_v10 software (Tree Star, Inc., Ashland, OR, USA), respectively, according to the previously reported methods[21].

    • Tomato seedlings were treated with S. baicalensis extracts to detect the expression of cyclin genes. Total RNA was extracted with the RNAiso Plus (TaKaRa, Otsu, Japan, cat. #108-95-2) from stems. The first-strand cDNA synthesis was conducted as described in the manufacturers instructions. qRT-PCR were conducted using the ABI QuantStudio 3 (Applied Biosystems, USA). ACTIN (SGN-U580609) was used as the internal control[22]. Three biological replicates were detected for each treatment.

    • The differences among experimental groups were assessed using DPS software. Principal component analysis (PCA) and clustering analysis were performed in R Studio Version 1.1.456 (www.rstudio.com) with R version 3.5.2 using ggplots (www.cran.r-project.org/web/packages/gplots) and factoextra (www.cran.r-project.org/web/packages/factoextra) packages, respectively. Six plants of each treatment were analyzed.

    • LC-MS/MS was used to determine whether baicalin, major active compound could be identified in the S. baicalensis extracts using the chemical baicalin as the actual standard. In negative mode, the detected parent ion for the actual standard of baicalin was 445 ([M-H]) and its predominant product ion was m/z 269 (C15H9O5) with optimized collision energy (CE) at 25 V (Fig. 2a). Therefore, the optimized mass pair for baicalin was 445/269 (Fig. 2b), which was then used in the multiple reaction monitoring (MRM). According to the retention time (RT) of baicalin standard (RT = 4.0 min) and the LC chromatogram of S. baicalensis extracts, two large peaks (RT = 3.97 min; RT = 4.67 min) in S. baicalensis extracts were obtained and it was confirmed that the first peak (RT = 3.97 min) was baicalin and the second peak (RT = 4.67 min) was probably an isomer of baicalin (Fig. 2c).

      Figure 2. 

      Mass spectrometry analysis showed that baicalin was the main active ingredient in S. baicalensis extract. (a), (b) Direct infused baicalin standard was used to optimize compound-dependent MS/MS parameters and create a multiple reaction monitoring (MRM) method on LC-MS/MS. (c) The predominant active compound in S. baicalensis extract was confirmed to be baicalin. The two large peaks at 3.97 min and 4.67 min were isomers of baicalin.

    • Several runs of preliminary experiments were performed to confirm the suitable concentrations of working solutions of S. baicalensis extracts and the actual standard of baicalin. It was determined that the suitable working solution concentration of S. baicalensis extracts was 6 g/L. According to the standard curve of baicalin, the concentration of baicalin in S. baicalensis extracts was 0.77 g/L. According to the dilution ratio of S. baicalensis extracts, the working concentration of baicalin was calculated to be 0.046 g/L. So, it was finally decided to use S. baicalensis extracts (6 g dry slices/L) and baicalin (0.046 g/L) to treat tomato seedlings and compare their effects on plant growth (Supplemental Fig. S1). Plant height, stem diameter, and leaflet area of tomato seedlings after five treatments were measured. It was found that S. baicalensis extracts promoted tomato growth compared with control (Fig. 3a). Specifically, S. baicalensis extracts in SR treatment enhanced plant height, stem diameter, and leaflet area by 8.00%, 9.22% and 21.84% compared to the control, respectively (Fig. 3bd). Baicalin as the main active ingredient of S. baicalensis extracts can also significantly promote the growth of tomato seedlings (Fig. 3e). For example, the plant height, stem diameter, and leaflet area of the SR group under baicalin treatment were 18.72%, 11.32%, and 1.81% higher than those of the control group, respectively (Fig. 3fh). The cyclin genes can affect cell growth, division, and differentiation by affecting the cell cycle, thereby regulating plant development[23]. The cyclin genes transcription in stems of tomato seedlings treated with S. baicalensis extracts and water indicate that S.baicalensis extracts may enhance cyclin expression to promote tomato seedling growth via increasing endoreduplication (Fig. 3i). Hereby, these data suggest that S. baicalensis extract and baicalin have similar effects on tomato development. Meaningfully, SR treatment is more conducive to tomato development.

      Figure 3. 

      Scutellaria baicalensis Georgi (S. baicalensis) extracts and baicalin affect height, stem diameter and leaflet size of tomato seedlings after treatments. (a), (e) Morphology of tomato seedlings after application of S. baicalensis extracts and baicalin. Scale bar = 5 cm. Treatments: Water control (CK), Spray (S), Root irrigation (R) and Spray and root irrigation (SR). (b), (f) Tomato plant height after application of S. baicalensis extracts and baicalin. (c), (g) Tomato stem diameter after application of S. baicalensis extracts and baicalin. (d), (h) Tomato leaflet size after application of S. baicalensis extracts and baicalin. (i) Analysis of cyclin genes expression in stems of tomato seedings treated with S. baicalensis extracts. Results are shown as means ± SD (n = 6). Values marked with the same letter within a sampling date are not significantly different at p < 0.05 according to Duncan's new multiple-range test.

    • To test whether S. baicalensis extract and baicalin influence the photosynthetic performance of tomato leaves, tomato seedlings were treated with S. baicalensis extracts and baicalin and determined their photosynthetic pigment content and photosynthetic rate. Chlorophyll a content, chlorophyll content, photosynthetic rate, and Fv/Fm of tomato seedlings in S group treated with S. baicalensis extracts were 1.05 times, 1.05 times, 1.29 times and 1.03 times higher relative to CK, respectively (Fig. 4af). Furthermore, the chlorophyll a content, total chlorophyll content, photosynthetic rate, PSII, and Fv/Fm were increased by 5.69%, 4.54%, 18.75%, 138.17%, and 8.68% in S, 11.15%, 8.49%, 14.77%, 18.69%, and 6.77% in SR, respectively, compared with CK under the baicalin treatment (Fig. 4gl). To determine the mechanism of S. baicalensis extracts enhancing photosynthesis, qRT-PCR was used to assess the expression of photosynthetic efficiency-related genes in leaves of tomato seedings treated with S. baicalensis extracts. Compared with the control, S. baicalensis extracts significantly activated expression of light-harvesting chlorophyll a/b-binding factor (SlLhcb1;1 and SlLhcb1;2)[24], rubisco activase gene (SlRca1)[25], and photosystem subunit (SlPsaE and SlPsaQ)[26] (Fig. 4m). In summary, S. baicalensis extracts and baicalin improved photosynthesis of tomato seedlings by increasing chlorophyll and carotenoid contents.

      Figure 4. 

      Leaf chlorophyll content and photosynthetic rates of tomato seedlings in response to Scutellaria baicalensis Georgi extracts and baicalin treatments. (a), (g) Leaf chlorophyll a contents of tomato seedlings after application of S. baicalensis extracts and baicalin. (b), (h) Leaf chlorophyll contents of tomato seedlings after application of S. baicalensis extracts and baicalin. (c), (i) Leaf carotenoid contents of tomato seedlings after application of S. baicalensis extracts and baicalin. (d), (j) Photosynthetic rates of tomato seedlings after application of S. baicalensis extracts and baicalin. (e), (k) Actual quantum efficiency (PSII) of tomato seedlings after application of S. baicalensis extracts and baicalin. (f), (l) Maximum quantum efficiency (Fv/Fm) of tomato seedlings after application of S. baicalensis extracts and baicalin. (m) Expression of the photosynthesis-related genes in the CK and tomato seedings treated with S. baicalensis extracts. Results are shown as means ± SD (n = 6). Values marked with the same letter within a sampling date are not significantly different at p < 0.05 according to Duncan's new multiple-range test.

    • The morphological indexes of tomato roots were measured to investigate the effects of S. baicalensis extracts and baicalin on underground tissues. Tomato roots were scanned and it was found that S. baicalensis extracts promoted the root development (Fig. 5a). Under S. baicalensis extracts treatment, total root length, average root diameter, root surface area, root volume, root node number, and root tip number in the SR group increased by 29.91%, 3.39%, 27.48%, 23.03%, 42.31%, and 22.78%, respectively, compared with CK. On the contrary, R treatment significantly inhibited root growth. Furthermore, it was found that baicalin can also significantly improve root development of tomato seedlings (Fig. 5h). Total root length, average root diameter, root surface area, root volume, root node number, and root tip number were significantly increased in SR-treated tomato seedlings than in CK group. (Fig. 5in). These data provided evidence that S. baicalensis extracts and baicalin significantly strengthen root system architecture.

      Figure 5. 

      Scutellaria baicalensis Georgi extracts and baicalin affect root physiological indicators after treatments. (a), (h) Morphology of tomato seedling roots after application of S. baicalensis extracts and baicalin. Scale bar = 2.5 cm. Total root length (RL), average root diameter (ARD), root surface area (RSA), root volume (RV), root node number (RNN) and root tip number (RTN) were measured after (b)−(g) application of S. baicalensis extract and (i)−(n) baicalin via WINRHIZO multi-parameter plant root analysis system. Results are shown as means ± SD (n = 6). Values marked with the same letter within a sampling date are not significantly different at p < 0.05 according to Duncan's new multiple-range test.

    • The dry weight of tomato seedlings after S. baicalensis extracts and baicalin treatment were examined. Under S. baicalensis extracts treatment, compared with CK, SR treatment increased the dry weight of aboveground tissues by 26.65% (Fig. 6a). However, SR treatment slightly increased the fresh weight of aboveground tissues. Compared with the CK group, SR treatment increased the dry weight of underground tissue by 28.66% (Fig. 6b). Under baicalin treatment, S treatment increased the dry weight of aboveground tissues by 27.03% relative to CK. The dry weight of aboveground tissues in the S treatment were increased by 27.03% compared with CK, respectively (Fig. 6c). The S treatments increased dry weight of underground tissues by 32.92% compared with CK (Fig. 6d). Meanwhile, S. baicalensis extracts and baicalin also significantly increased the dry weight of tomato seedlings (Supplemental Fig. S2). Therefore, S. baicalensis extracts and baicalin significantly enhanced the biomass of tomato seedlings.

      Figure 6. 

      Scutellaria baicalensis Georgi extracts and baicalin affect the aboveground and underground tissue dry weight of tomato seedlings. (a), (c) Dry weight (DW) of tomato aboveground tissues after S. baicalensis extracts and baicalin treatments. (b), (d) DW of tomato underground tissues after S. baicalensis extracts and baicalin treatments. Results are shown as means ± SD (n = 6). Values marked with the same letter within a sampling date are not significantly different at p < 0.05 according to Duncan's new multiple-range test.

    • Root-shoot ratio and strong seedlings index (SSI) can be used to objectively evaluate the robustness of seedlings[27]. Therefore, the root-shoot ratio and SSI of tomato seedlings treated with S. baicalensis extract and baicalin were determined. Under S. baicalensis extracts treatment, the root-shoot ratio and SSI of the SR group were 1.62 times and 1.47 times that of CK, respectively (Fig. 7a, b). Under baicalin treatment, SR treatment significantly increased the root-shoot ratio and SSI of aboveground tissues, which were 58.60% and 18.50% higher than CK, respectively (Fig. 7c, d).

      Figure 7. 

      Effects of different treatments of S. baicalensis extracts and baicalin on physiological data of tomato seedlings. (a), (b) The root: shoot ratio and strong seedling index (SSI) of tomato seedlings after application of S. baicalensis extracts. (c), (d) The root: shoot ratio and SSI of tomato seedlings after application of baicalin. Results are shown as means ± SD (n = 6). Values marked with the same letter within a sampling date are not significantly different at p < 0.05 according to Duncan's new multiple-range test. (e) Clustering analysis and (f) principal component analysis were used to analyze physiological indicators related to tomato seedling development. AF, aboveground fresh weight; PH, plant height; SD, Stem diameter; Caro, carotenoid content; ARD, average root diameter; SSI, strong seedling index; LA, leaflet area; RS, root: shoot ratio; PR, photosynthetic rate; RL, root length; RSA, root surface area; RV, root volume; Chl, chlorophyll content; Ca, chlorophyll a. B and S represent baicalin and S. baicalensis, respectively. Baicalin treating is marked using dotted lines. R programming was used for data analysis.

      Cluster analysis and principal component analysis were conducted based on physiological data after S. baicalensis extracts and baicalin treatments. Compared with the control, SR treatment dramatically enhanced tomato seedling growth and development via cluster analysis. More meaningfully, SR treatment can be clustered together (Fig. 7e). Principal component analysis showed that the effect of SR treatment on tomato seedlings was the farthest from that of CK (Fig. 7f). These data showed that the effects of S. baicalensis extract and baicalin treatment on most physiological indexes of tomato seedlings were generally consistent, and showed the best effect under SR application. In general, the effect of S. baicalensis extract treatment was slightly better than that of baicalin treatment, which may be because S. baicalensis extract is a mixture and may contain other active compounds.

    • Biostimulants are organic compounds, inorganic compounds, or microorganisms that can improve crop resistance and improve crop quality. When applied to plant leaves or rhizosphere, biostimulants regulate physiological processes and nutrient uptake in plants[28]. Biostimulants have been widely used in horticulture and agricultural crops to increase yields. Humic acid increases the germination rate of tomato, wheat, and rice seeds and promotes the elongation of lateral roots, which in turn increases the yield and improves the quality of crops[4]. Chitooligosaccharides with foliar spraying can significantly accumulate proline in wheat and increase chlorophyll content in leaves to improve photosynthesis[29]. Chitosan can also inhibit the growth of pathogens in soil and improve soil aggregate structure, thereby increasing crop yield and quality[30]. In summary, the application of biostimulants in agriculture has achieved some important results.

      Currently, biostimulants are of great value in efficient agricultural production and are therefore widely used to enhance crop productivity capacity[31]. The application of biostimulants with alginate and chitooligosaccharides as the main components are becoming more and more extensive[32]. Chinese herbal medicines possess the advantages of being green, pollution-free, and environmentally friendly[33]. However, application of Chinese herbal medicine extracts as plant-derived biostimulants in agriculture is rarely described. It was observed that the S. baicalensis extracts and baicalin significantly promote stem and root growth, increase tomato biomass, enhance leaf photosynthetic capacity, and eventually lead to the robust growth of tomato seedlings (Fig. 8). This is consistent with previous reports that the application of Boosten, Megafol, and Isabion significantly promoted plant growth and increased plant biomass[34].

      Figure 8. 

      Schematic illustration of a proposed model showing effects of S. baicalensis extracts and baicalin on growth and development of tomato seedlings.

      The manner of biostimulant treatment is an important factor influencing plant development[35]. The main function of plant leaves is to carry out photosynthesis to produce organics, and can also absorb exogenous nutrients. Foliar spraying can make plants absorb and utilize biostimulants quickly and evenly, which can effectively improve the photosynthesis efficiency and ultimately promote the rapid growth of plants[36]. Plant roots are the foundation of life. Reasonable irrigation can directly provide proper biostimulants for plant roots, which significantly enhances the vitality of roots, thereby further improving the absorption capacity of plants for water and fertilizer[37]. Therefore, the combination of spraying and root irrigation can have an overall better effect on plant growth. Cluster analysis and PCA were carried out based on all phenotypic data with three treatments and it was found that the SR treatment was better in this study.

      S. baicalensis, a natural herb, is rich in active substances that do not pollute the environment and cause pesticide residues[38]. Some studies have reported that Chinese herbal extracts affect plant hormone biosynthesis and their gene expression to regulate plant development[12]. However, there are few studies on the role of S. baicalensis in plant growth. Spraying and root irrigation with S. baicalensis extracts and baicalin can significantly promote the growth, stomatal conductance, and transpiration rate of tomato seedlings (Supplemental Fig. S3). Plants store energy through photosynthesis, which is conducive to the formation of crop yield and quality[39]. Chlorophyll and carotenoids of leaves participate in light absorption and transmission. Therefore, the content and composition of photosynthetic pigments play an important role in the photosynthetic rate of leaves[40]. The reason may be that S. baicalensis extracts and baicalin improve photosynthesis in leaves and ultimately make plants grow robustly. The root system has the function of absorbing, transporting, and storing nutrients, which determines the vigorous growth of plants[41]. S. baicalensis extract treatment can expand the root system (Fig. 5a). The accumulation of biomass is an important characterization of plant growth and metabolism[42]. S. baicalensis extracts treatment dramatically increased tomato seedling biomass (Fig. 6a, b). Chinese herbal medicine extracts play an active role in plant growth. As a plant-derived biostimulant, it does not produce drug residues on plants. Therefore, Chinese herbal medicine extract as a biostimulant has great prospects in agriculture. The photosynthesis of plants directly influences the synthesis and accumulation of organic matter, which is a direct factor affecting crop yield[43]. Interestingly, the expression of photosynthesis-related genes (SlLhcb1;1, SlLhcb1;2, SlRca1, SlPsaE, and SlPsaQ) was verified by qRT-PCR (Fig. 4). The results showed that the treatment of S. baicalensis extracts increased the expression of multiple photosynthesis-related genes, which was consistent with the increased photosynthetic rate of tomato after treatment with S. baicalensis extracts. Moreover, cyclins can regulate the division and differentiation of cells by affecting the cell cycle process, and ultimately modulate the biomass of plants[44]. Several Chinese herbal extracts have been confirmed to be involved in plant photosynthesis[19]. S. baicalensis extracts recognize a set of genes involved in cell cycle progression, by the increased endoreduplication of tomato stems (Fig. 3). The mechanism of S. baicalensis extracts enhancing photosynthetic capacity and increasing biomass requires further research.

      As an exogenous non-nutritive chemical, biostimulants can be absorbed and transferred to different tissues of plants, affecting their growth and metabolic processes[45]. The effect of biostimulants are affected by many factors[46]. The low concentration also promoted tomato seedling growth and development without statistical significance, while the high concentration of the extract can inhibit the growth of tomato seedlings possibly due to overdosage. In conclusion, biostimulants are not equivalent to conventional fertilizers, but improve the physiological state of plants to affect plant growth and development[47,48]. Here, mass spectrometry was used to detect the possible active compounds in S. baicalensis extracts, which is baicalin. We then applied a certain dosage of baicalin on plants to compare its effects on plant development with S. baicalensis extracts and confirmed that baicalin indeed is the predominant active compound in the extract. The effect of S. baicalensis extracts on tomato seedling growth were slightly better than that of baicalin, which may be due to the fact that S. baicalensis extracts as a mixture may contain other active components. At the vegetative growth stage of the tomato seedlings, both S. baicalensis extracts and baicalin treatments promoted seedling growth, improved leaf photosynthetic efficiency and increased seedling index. These data suggest that the Chinese herbal extracts and their active compounds are important sources of biostimulants and play an important role in regulating plant growth and development, which may contribute to the development of sustainable agriculture.

    • The application of biostimulants in agricultural production may solve a series of problems such as environmental pollution caused by the excessive use of chemical fertilizers[49]. These results showed that S. baicalensis extracts and baicalin had very similar effects in boosting stem and root development, increasing leaf photosynthetic capacity, improving tomato biomass, and eventually contributed to the tomato seedling vigorous growth (Fig. 8). Therefore, S. baicalensis has the potential to serve as a source of biostimulants that can enhance resistance to abiotic stress and promote plant nutrient absorption.

    • The authors confirm contribution to the paper as follows: software, formal analysis, bioinformatics analysis: Liu G; conceptualization: Li J, Bao Z; investigation: Xin J, Li C, Ma M, Fan J, Xu C, Ma F; methodology, data curation: Xin J; funding acquisition: Liu G, Bao Z; resources: Fang D, Bao Z; supervision: Liu G, Ma F, Bao Z; writing–review & editing: Liu G, Bao Z. All authors reviewed the results and approved the final version of the manuscript.

    • The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

      • This research was supported by the Taishan Scholar Foundation of Shandong Province (tsqn201812034), Agricultural Seed Project of Shandong Province (2020LZGC005), China Postdoctoral Science Foundation (2022M711967), Key research and development program of Shandong Province (2021LZGC017), and the National Natural Science Foundation of China (31872951).

      • The authors declare that they have no conflict of interest.

      • # Authors contributed equally: Genzhong Liu, Jinyang Xin

      • Supplemental Table S1 Primers used in this study.
      • Supplemental Fig. S1 Preparation of crude extract solutions for application.
      • Supplemental Fig. S2 Scutellaria baicalensis Georgi extracts and baicalin affect the aboveground and underground tissue fresh weight of tomato seedlings.
      • Supplemental Fig. S3 The stomatal conductance and transpiration rate of tomato seedling leaves in response to Scutellaria baicalensis Georgi extracts and baicalin treatments.
      • Supplemental Fig. S4 The endoreduplication level in tomato stem cells (A) and leaf cells (B) after Scutellaria baicalensis Georgi extracts treatments.
      • Copyright: © 2024 by the author(s). Published by Maximum Academic Press, Fayetteville, GA. This article is an open access article distributed under Creative Commons Attribution License (CC BY 4.0), visit https://creativecommons.org/licenses/by/4.0/.
    Figure (8)  References (49)
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    Liu G, Xin J, Li C, Ma M, Fan J, et al. 2024. Scutellaria baicalensis Georgi extracts and its active compound baicalin promote tomato seedling growth. Vegetable Research 4: e023 doi: 10.48130/vegres-0024-0023
    Liu G, Xin J, Li C, Ma M, Fan J, et al. 2024. Scutellaria baicalensis Georgi extracts and its active compound baicalin promote tomato seedling growth. Vegetable Research 4: e023 doi: 10.48130/vegres-0024-0023

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