Functional Identification Of Anthocyanin Regulatory Genes CaMYB And CaMYC In Pepper (Capsicum Annuum L.)

Pepper is one of the most essential vegetables with a high economic value in our county.Purple peppers are relatively rare varieties,so selecting purple pepper cultivars has become a very important part in pepper breeding.Purple is due to the accumulation of anthocyanin.The complex MBW are composed of MYB,WD40 and bHLH,regulating anthocyanin synthesis at the transcriptional level,and environmental factors also affect the anthocyanin contents.Some genes expression is related to anthocyanin accumulation in purple pepper Z1.Previous study in our lab used virus-induced gene silencing technology to silence transcription factor CaMYB,proving that CaMYB has an effect on anthocyanin biosynthesis,by regulation the expression of structural genes to affect anthocyanin accumulation,awhile regulating the expression of genes of MYC will be showing a reduction,and another regulatory gene CaMYC would show down regulation.However,it is unclear that whether bHLH transcription factor CaMYC is involved in anthocyanin biosynthesis,and is response to environmental stress.The relationship between CaMYB and CaMYC during anthocyanin accumulation in pepper leaves is unknown.Therefore,this article explores CaMYC is response to the low temperature and it would cause the changes of structural genes expression,using VIGS technology to silence CaMYB and Ca MYC separately and commonly caused differences of anthocyanin content and using the transgenic technology allows overexpression of CaMYB in pepper to increase the anthocyanin accumulation.The main results are:1.CaMYC involves in regulation of anthocyanin biosynthesis in pepper leaves during developmental stage.Leaf colors are mainly green on the 6th position leaves in purple pepper Z1,due to the regulation of CaMYC induces anthocyanin related genes showing downregulation,resulting the variation of the anthocyanin contents in leaves.2.Low temperature can promote anthocyanin accumulation in pepper leaves and transcription factors CaMYC can respond to low temperatureLow temperatures could promote the accumulation of anthocyanin in pepper leaves,and during a period of time,anthocyanin content is consistent with low temperature stress time.Low temperature induced bHLH transcription factor CaMYC positively regulate anthocyaninaccumulation in pepper leaves.When the pepper has been treated by low temperature for 6hours,the expression of regulatory genes CaMYB,CaMYC and structural genes PAL,GST,C4 H,ANP,F3'5'H,4CL,ANS,CHS,UFGT,F3 H,DFR,CHI show an upward trend except for WD40,this indicates that regulation complexe MBW can act on the structural genes expression in response to low temperature,causing the increasing anthocyanin content.It would be helpful to have a better understanding of the anthocyanin regulatory mechanisms of regulation complex MBW under environmental stimuli.3.Preliminary functional vertification of CaMYC and CaMYB by VIGS technologyBy silencing CaMYB and/or CaMYC,the results show that in pepper leaves,the expression of structural genes GST,ANP,F3'5'H,ANS,CHS,UFGT,F3 H,DFR,CHI will be downregulated because of silencing of CaMYC and/or CaMYB genes.This suggests that transcription factors CaMYB and CaMYC can regulate anthocyanin biosynthesis,both of which affect anthocyanin content in pepper leaves by regulating the expression of anthocyanin related structural genes.In addition,there might be some interaction between CaMYC and CaMYB in regulating anthocyanin biosynthesis pathway in chili leaves,co-regulating the regulation of anthocyanin,it may clear the role of transcript factors CaMYB and CaMYC in anthocyanin accumulation in pepper leaves,but it also need to do some work related to proteins to have a further verification.4.Overexpression of CaMYB in pepper callusBy using transgenic technology,overexpression of CaMYB gene in pepper callus could induce the upregulation expression of anthocyanin biosynthetic pathway related genes GST,ANP,F3'5'H,MYC,CHS,UFGT,F3 H,DFR,CHI,meanwhile the anthocyanin content in pepper callus grow largely.Overexpression CaMYB in callus may cause the expression of MYC,which regulate anthocyanin together.This shows CaMYB plays a very important role in MBW regulation complexe in the regulation of anthocyanin biosynthesis pathway.