Figures (3)  Tables (1)

    • Figure 1. 

      Morphological characteristics of trichomes in A. annua. AaGST, glandular secreting trichome; Ba, basal cells; St, stalk cells; Suc, subapical cells; Ac, apical cells; SS, subcutaneous space; AaTNG, T-shaped non-glandular trichome.

    • Figure 2. 

      Regulatory network model for trichome development in A. annua. Arrows indicate a positive influence while blocked lines indicate negative regulation.

    • Figure 3. 

      Biosynthetic pathways of artemisinin biosynthesis. AA, Artemisinic acid; AAA, Artemisinic aldehyde; AAOH, Artemisinic alcohol; AB, Arteannuin B; AD, amorpha-4,11-diene; ADH1, alcohol dehydrogenase 1; ADS, amorpha-4,11-diene synthase; ALDH1, aldehyde dehydrogenase 1; CPR, cytochrome P450 reductase; CYP71AV1, cytochrome P450 monooxygenase; DBR2, artemisinic aldehyde double bond reductase 2; DHAA, dihydroartemisinic acid; DHAAA, dihydroartemisinic aldehyde; DHAAOH, dihydroartemisinic alcohol; DMAPP, dimethylallyl diphosphate; FPP, farnesyl diphosphate; FPS, farnesyl pyrophosphate synthase; GPP, geranyl diphosphate; IDI, isopentenyl-diphosphate isomerase; IPP, isopentenyl diphosphate; MEP, 2-C-methyl-D-erythritol 4-phosphate; MVA, mevalonic acid; RED1, dihydroartemisinic aldehyde reductase 1.

    • Types Name Effect Target gene Interacting proteins Refs
      R2R3-MYB AaMYB1 (+)AaGST initiation
      (+)artemisinin biosynthesis      		 ADS, CYP71AV1 [40]
      AaMYB5 (−)AaGST formation
      (−)artemisinin biosynthesis      		 AaHD1, AaMYB16, AaJAZ8 [41]
      AaMYB16 (+)AaGST initiation
      (+)AaTNG initiation
      (+)artemisinin biosynthesis      		 AaHD1, AaMYB5 [41]
      AaMYB17 (+)AaGST initiation
      (+)artemisinin biosynthesis      		 [42]
      AaMIXTA1 (+)AaGST initiation
      (+)AaTNG initiation
      (+)artemisinin biosynthesis      		 AaCYP77A1, AaCYP86A1, AaKCS5, AaCER1, AaABCG12 [43]
      AaTLR1 (−)AaGST formation
      (−)artemisinin biosynthesis      		 ADS, CYP71AV1, DBR2, ALDH1 AaTLR2, AaWOX1 [44]
      AaTLR3 (−)AaGST formation
      (−)artemisinin biosynthesis      		 ADS, CYP71AV1, DBR2, ALDH1 AaCycTL [45]
      AaTAR2 (+)AaGST initiation
      (+)AaTNG initiation
      (+)artemisinin biosynthesis      		 ADS, CYP71AV1, DBR2, ALDH1 [46]
      AaMYB108-like (+)AaGST initiation
      (+)AaTNG initiation
      (+)artemisinin biosynthesis      		 AaHD1 AaHD8 [47]
      HD-ZIP AaHD1 (+)AaGST initiation
      (+)AaTNG initiation
      (+)artemisinin biosynthesis      		 AaGSW2 AaJAZ8 [34]
      AaHD8 (+)AaGST initiation
      (+)AaTNG initiation
      (+)artemisinin biosynthesis      		 AaCYP86A4, AaFDH AaMIXTA1 [48]
      AP2/ERF AaTAR1 (+)AaGST formation
      (+)AaTNG formation
      (+)artemisinin biosynthesis      		 ADS, CYP71AV1 AaCycTL [38]
      AaWIN1 (+)AaGST formation
      (+)artemisinin biosynthesis      		 AaGSW2 AaMIXTA1 [49]
      AaSPL9 (+)AaGST initiation
      (+)artemisinin biosynthesis      		 AaGSW2 AaHD1 [50]
      WRKY AaGSW2 (+)AaGST initiation
      (+)artemisinin biosynthesis      		 AaHD1, AaHD8 [51]
      SAP AaSAP1 (+)AaGST formation
      (+)artemisinin biosynthesis      		 [52]
      LEAFY-like AaTLR2 (−)AaGST initiation
      (−)AaTNG initiation
      (−)artemisinin biosynthesis      		 ADS, CYP71AV1, DBR2, ALDH1 AaWOX1 [44]
      MADS-box AaSEP1 (+)AaGST initiation
      (+)artemisinin biosynthesis      		 AaGSW2 AaMYB16 AaJAZ8 [53]
      YABBY AaYABBY5 (+)AaGST formation
      (+)artemisinin biosynthesis      		 ADS, CYP71AV1, DBR2, ALDH1 [54]
      bHLH AaGL3-like (+)AaGST formation
      (+)AaTNG formation
      (+)artemisinin biosynthesis      		 AaJAZ8 [55]
      Phytohormones JA (+)AaGST formation
      (+)AaTNG formation
      (+)artemisinin biosynthesis      		 AaHD1, AaHD8, AaJAZ8, AaMYB5 [34,41,56,57]
      GA (+)AaTNG formation(GA3)
      (+)AaGST formation(GA1/4)
      (+)artemisinin biosynthesis(GA1/4)      		 [56,58]
      CK (+)AaGST formation
      (+)AaTNG formation
      (+)artemisinin biosynthesis      		 [56]
      ABA (+)AaGST formation
      (+)artemisinin biosynthesis      		 [59]
      MicroRNAs miR160 (−)AaGST formation
      (−)artemisinin biosynthesis      		 AaARF1 [60]
      miR828 (−)AaGST formation
      (−)artemisinin biosynthesis      		 AaMYB17 [61]
      +, positive; −, negative.

      Table 1. 

      The main factors regulating the growth and development of A. annua trichomes.