Figures (8)  Tables (1)

    • Figure 1. 

      Classification and structural characteristics of plant MYB transcription factors.

    • Figure 2. 

      Number of R2R3-MYB subfamily members in tropical fruit.

    • Figure 3. 

      Phylogenetic Neighbor-Joining (NJ) Tree.

    • Figure 4. 

      Plant anthocyanin synthesis pathway. CHS (chalcone synthase), CHI (chalcone isomerase), F3H(flavanone 3-hydroxylase), F3′H (flavonoid 3′-hydroxylase Enzyme), DFR (dihydroflavonol 4-reductase), ANS (anthocyanin synthase) and UFGT (UDP glucose: flavonoid 3-O-glucosyltransferase), GST (Glutathione S-transferase), EAR (ERF-associated amphiphilic repression; Ethylene reaction factor related reaction inhibitory motifs).

    • Figure 5. 

      Synthesis or decomposition of anthocyanins and flavonoids etc. by MYB transcription factor in tropical fruit. BHLH (basic helix-loop-helix), WD40 (WD40 repeat proteins), NAC (NAM, ATAF1, ATAF2 and CUC2). Note: blue represents inhibition, red represents activation and promotion.

    • Figure 6. 

      Effects of MYB transcription factors on abiotic and biotic stress tolerance in tropical fruit. ABA1/ABA2 (genes responsible for ABA synthesis), ABI5 (Abscisic acid-insensitive 5, Key genes in response to ABA signals), CBF (C-repeat binding transcription factor/dehydrate responsive element binding factor, DREB), CHS (chalcone isomerase), FAD (fatty acid desaturase), CCR (Cinnamoyl CoA reductase), HCT (hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase), COMT (caffeic acid 3-O-methyltransferase), PAL (phenylalanine ammonia-lyase), CCOAOMT (caf-feoyl-CoA O-methyltransferase), UGFT (UDP-glucose: flavonoid-3-O-glucosyltransferase), FLS (flavonol synthase), IFS (isoflavone synthase), F35H (flavonoid 3,5-hydroxylases), HDA (histone deacetylase), OSC (Oxidosqualene cyclase).

    • Figure 7. 

      Regulatory effects of MYB transcription factor on fruit ripening and fruit quality in tropical fruit crops. GWD (glucan-water dikinase), SEX4 (phosphoglucan phosphatases starch excess 4), BAM (Beta-amylase), AMY (α-amylases), MEX (maltose excess protein), pGlcT (plastidic glucose translocator), F5H (ferulate 5-hydroxylase), POD (Peroxidase), 4CL (4-coumarate;coenzyme A ligase), PAL (phenylalanine ammonia-lyase), PDS (Phytoene desaturase), CHY (Chymopapain), PME (pectinmethylesterase), PGs (polygalacturonases), NI (neutral/alkaline invertase), PGK (Phosphoglycerate kinase), Ca2+-ATPase (A multiregulated enzyme that is stimulated by calmodulin (CaM), KCI and lysophospholipids), ALMT (aluminum-activated malate transporter), ADH (Alcohol dehydrogenase), CYP76AD1 (cytochrome P 450 76AD1), DODA ((DOPA)-4,5-dioxygenase), AP2 (APETALA2), BRG2 (RING finger E3 ligases). MaACS1 (ACC synthase), MaXTH5 (cell wall modifying enzyme), MaPG3 (exopolymeric galacturonidase), MaEXPA15 (α-expansion protein) Note: blue represents inhibition, red represents activation and promotion.

    • Figure 8. 

      Effects of MYB transcription factors on tropical fruit crops flowers. PH1 (P-ATPase), CHI (chalcone isomerase), F3H (flavanone 3-hydroxylase), DFR (dihydroflavonol 4-reductase).

    • Latin namePlant nameGeneGene founctionReference
      Litchi chinensisLitchLcMYB1 (KY302802.1)Regulates the accumulation of anthocyanins[68−72]
      LcR1MYB1 (QCF47524.1)Negative regulation of anthocyanin biosynthesis[73]
      LcMYB5 (Unigene 0002103)Anthocyanin biosynthesis, tissue acidification[127]
      LcMYBx (UCU01159.1)Negatively correlated with the synthesis of leaf anthocyanins[74]
      Mangifera indicaMangoMinMYB10Possible involvement in the regulation of anthocyanin accumulation in fruits[91]
      MinMYBPAPossible involvement in the regulation of anthocyanin accumulation in peels[92]
      MiMYB1 (NC_056567.1)Peel anthocyanin synthesis[93]
      Musa acuminataBananaMaMYB1Response to drought, low temperature, salt stress[101]
      MaMYB14/63/110Response process of salt stress[105]
      MaMYBR1Resistance to fusarium wilt.[103]
      MaMYB3/4/32Fruit ripening[119]
      MaMYB4 (Ma03_g21920)Inhibits banana anthocyanin biosynthesis and fruit ripeing; Negatively regulates the synthesis of banana Regulates the anthocyanins and synthesis of fatty acids[75,106,118]
      MaMYB3Delay banana fruit ripening[116]
      MusaMYB31Inhibits banana lignin and polyphenol biosynthesis[107]
      MaMYB16LInhibited fruit ripening[115]
      MaMYB16SPromotes ripening of banana fruit[115]
      Musa spp.MpMYBS3 (KM379134)Participate in the regulation of cold signaling pathways.[108]
      Musa paradisiacaMYB108 (Ma09_g15940)Regulates the growth and development of banana leaves and roots under long-term magnesium deficiency conditions[104]
      Ananas comosusPineappleAcoMYB1 (XM_020230319)Regulates early development and late ripening in pineapples in response to drought and low temperature stress[109]
      AcoMYB4Inhibit ABA synthesis[110]
      Hylocereus polyrhizusPitayaHuMYB1814Synthesis of Anthocyanins[83]
      Hylocereus undatusUnigene0036816May be to relevant the color difference of dragon fruit pulp[84]
      Unigene0032395May be to relevany the color difference of dragon fruit pulp[84]
      Unigene0034590May be to relevant the color difference of dragon fruit pulp[84]
      Hylocereus polyrhizusHuMYB1Inhibits the expression of β-galactose-related genes.[121]
      Garcinia mangostanaMangosteenGmMYB10 (ACM62751.1)Regulation of anthocyanin biosynthesis before and after fruit harvest[85]
      GmMYB30 (AID69234.1)Cell wall thickening, lignin
      biosynthesis and stress response.
      [128]
      Myrica rubraBayberryMrMYB1 (GQ340767)Expression is induced by light signals, which then affects anthocyanin accumulation[76−80]
      MrMYB6 (c24596_g1)May negatively regulate the anthocyanins and PA (proanthocyanidin)accumulation[81]
      Macadamia
      integrifolia      		Macadamia nutsMiMYB1 (QIJ70646.1)Involved in stress response[111]
      MiMYB2 (QIJ70647.1)Related to growth[133]
      Carica papayaPapayaCPMYB1Fruit softening, carotenoid accumulation, fruit ripening[120]
      CPMYB-2Fruit softening, carotenoid accumulation, fruit ripening[120]
      Theobroma cacaoCocoaTcMYB113Regulation of flavonoid synthesis genes to determine red pod color in cocoa beans[86]
      Tc-MYBPAInvolved in the synthesis of anthocyanins and procyanidins in cocoa[88]
      MYB(gene18079)Involved in the regulation of cocoa pod color[87]
      Citrus unshiuCitrusCitMYB52Transcriptional regulation involved in sucrose metabolism[11]
      Citrus reticulataCitMYB52Negatively regulate citrate accumulation, Inhibits the breakdown of sucrose[121]
      Fortunella japonicaCitMYB20 (MN689609)Associated with citrus canker resistance[112]
      C. reticulata/C. sinensisCiMYB42 (Ciclev10021695m)Involved in the biosynthesis of citrus limonoids[113]
      Dimocarpus LonganLonganMYB-related-R1May be related to chromosome telomere structure and anthocyanin synthesis[89]
      MYB14May be to relevant the flowering process of longan[134]
      Syzygium samarangenseWax appleSsMYB1/4/20/54/77 (Transcriptome database:PRJNA284092)Promote lignin synthesis[63]
      SsMYB108/114/308Promote lignin synthesis[63]
      SsMYB3/5/6/10/33/39
      (comp40847_c1/
      comp186052_c0/
      comp17591_c0/
      comp_45853_c0/
      comp_44103_c0      		Promote lignin synthesis[63]
      SsMYB44/48/86/306/330/C1Related to postharvest lignin synthesis[63]
      SsMYB48Inhibit lignin synthesis[63]
      Eriobotrya japonicaLoquatEjMYB1 (KF767453)Fruit chilling lignification[123,124]
      EjMYB2 (KF767454)Lignification Negative Regulator[43,123,124]
      EjMYB8Promote lignin synthesis[125]
      EjMYB9Promote lignin synthesis[125]

      Table 1. 

      MYB genes and their main functions in tropical fruit.