A wake-up call: signaling in regulating ornamental geophytes dormancy

Yajie Zhao; Chang Liu; Juanjuan Sui; Jiahui Liang; Jintao Ge; Jingru Li; Wenqiang Pan; Mingfang Yi; Yunpeng Du; Jian Wu; Yajie Zhao; Chang Liu; Juanjuan Sui; Jiahui Liang; Jintao Ge; Jingru Li; Wenqiang Pan; Mingfang Yi; Yunpeng Du; Jian Wu

doi:10.48130/OPR-2022-0008

Figures (3) Tables (2)

Figure 1.
Photos to document the classification and morphological diversity of geophytes. (a) Dormant lily bulbs, (b) gladiolus corms, (c) Zantedeschia aethiopica tuber, (d) Canna indica rhizome, (e) Dahlia tuberous root. ab: apical bud; ax: axillary bud; bd: bud; bp: basal plate; br: branch root; cr: root crown; nd: node; rt: root; rz: rhizome; sc: scale; st: stem root; tr: tuberous root. The scale bar represents 1 cm.
Figure 2.
Biochemical and physiological processes occur during the whole process of dormancy in geophytes. In autumn, low temperature and short days induce endogenous ABA and inhibit CKs and GA. Besides, soluble sugars are decreased in shoots along with blocked PD and slow cell division. During the winter, long-term cold treatment contributes to decreasing ABA content in dormant organs and promoting GA, CKs, and soluble sugars. Meanwhile, callose around the PD is degraded which helps to active cell communication and cell division in buds. When the temperature and light are suitable for corm sprouting, ABA is continuously decreased and soluble sugars are used for plant growth. CDR: corm dormancy release; DR: Dormancy release; LD: Long day; LT: low temperature; SD: short day.
Figure 3.
The interplay among hormones and carbohydrates in regulating GDR. During GDR, ABA is the master hormone that could delay dormancy release by repressing cell division, blocking cell communication via callose, and inhibiting the biosynthesis of DNA, RNA, and protein by releasing SnRK1. Other hormones like GA, CKs, KARs, and ETH could interplay with ABA via transcription factors. A solid line represents the direct effect, and a dashed line represents the indirect effect. The interplay is summarized from different species. ABA: abscisic acid; ABI5: ABA INSENSITIVE 5; ACC: 1-Aminocyclopropane-1-carboxylic acid; AIL1: AINTEGUMENTA-like 1; ARR: RESPONSE REGULATOR 1; CALS1: CALLOSE SYNTHASE 1; CKs: cytokinins; CYP707A: CYTOCHROME P450, FAMILY 707, SUBFAMILY A; CYCD: D type CYCLINS; DAM: Dormancy-Associated MADS-Box; DELLA: aspartic acid–glutamic acid–leucine–leucine–alanine; EBB3: EARLY BUD-BREAK 3; ETH: ethylene; ETR1: Ethylene Receptor 1; FT: FLOWER LOCUS T; GA: Gibberellic acid; GA2ox1: Gibberellin 2-Oxidase 1; GA20ox1: Gibberellin 20-Oxidase 1; GA3ox1: Gibberellin 3-Oxidase 1; IPT: ISOPENTENYL TRANSFERASE; KARs: Karrikins; KAI2: KARRIKIN-INSENSITIVE 2; LAP1: Like- APETALA 1; NAC: NAM, ATAF, CUC; NCED: 9-CIS-EPOXYCAROTENOID DIOXYGENASE; PP2C: Protein phosphatase 2C; SnRK1/2: SNF1-related protein kinase 1; TCP: Teosinte Branched Cyldoeia/PCF; TOR1: Target of Rapamycin; SMXL2: SMAX1-LIKE.

Modification type	Regulation factors^*	Functional class^*	Target genes^*	References
Chromatin remodeling complexes	BRM	SWI2/SNF2-like	FT, CO, SOC1	[91]
Chromatin remodeling complexes	EBS	BAH and PHD domain-containing protein	FT	[93]
Heterochromatin	LHP1	HP1 homologue	FT	[91]
Histone deacetylation	FLD	Homologous to a subunit of histone deacetylase complexes	FLC	[91]
Histone deacetylation	FVE	Putative subunit of histone deacetylase complex	FLC	[91]
Histone monoubiquitination	HUB1/2	E3 homologs	FLC	[94]
Histone methylation	MRG1/2	H3K36me3	FT	[95]
Histone methylation	VRN1/2	H3k27me3	FLC, FT	[91,96]
Histone demethylation	JMJ30	Histone demethylase	SnRK2.8	[97]
DNA methylation	MET1	Maintenance CpNpG methyltransferase	FLC	[91]
^* BAH: bromo-adjacent homology; BRM: BRAHMA; CO: CONSTANS; EBS: EARLY BOLTING IN SHORT DAYS; FLC: FLOWER LOCUS C; FLD: FLOWER LOCUS D; FT: FLOWER LOCUS T; FVE: FLOWER LOCUS VE; HUB: HISTONE MONO-UBIQUITINATION; JMJ30: JUMONJI C DOMAIN-CONTAINING PROTEIN 30; LHP1: LIKE HETEROCHROMATIN PROTEIN; MET1: METHYLTRANSFERASE 1; MRG: MORF RELATED GENE 1; PHD: Plant homeodomain; SnRK: SNF1-related protein kinase 1; SOC1: SUPPRESSOR OF OVEREXPRESSION OF CO 1; SWI2/SNF2: SWITCHING2/ SUCROSE NONFERMENTING; VRN: VERNALIZATION.

Table 1.

Dormancy associated genes regulated by epigenetics.

miRNA	Targets^*	Species	Function	Reference
miR156	SPL	Paeonia suffruticosa	Bud dormancy release	[105]
miR159	MdMYB33 and MdMYB65	Malus domestica	ABA homeostasis	[102]
miR159	MYB/TCP	Lilium pumilum	Bulb dormancy release	[90]
miR160	ARF	Lilium pumilum	Bulb dormancy release	[90]
miR169	HAP2	Populus tremuloides	Vegetative bud dormancy	[106]
miR169	NF-YA	Prunus mume	Bud dormancy release	[101]
miR172	AP2	Paeonia suffruticosa	Bud dormancy release	[105]
miR319c	TCP2	Camellia sinensis	Apical bud burst	[107]
miR390	TAS3	Pyrus pyrifolia	Endodormancy release	[108]
miR390	CDPK1	Solanum tuberosum	Tuber dormancy	[104]
miR6390	DAM	Pyrus pyrifolia	Dormancy transition	[103]
^* AP: APETALA; ARF: AUXIN RESPONSE FACTOR; CDPK: CALCIUM-DEPENDENT PROTEIN KINASE; DAM: DORMANCY-ASSOCIATED MADS-BOX; HAP: HAPLESS; MYB: MYELOBLASTOSIS; NF-YA: Nuclear Transcription Factor Y Subunit Alpha; SPL: SQUAMOSA PROMOTER BINDING PROTEIN-LIKE; TAS: TRANS-ACTING SIRNA3; TCP: TEOSINTE BRANCHED1/CYCLOIDEA/PCF.

Table 2.

miRNA related to bud dormancy.