Research On Differential Accumulation And Light-induced Accumulation Of Anthocyanins In Potato Tubers

Potato(Solanum tuberosum L.)is the fourth most important food crop in the world and China is now the world’s number one potato producer,which allows potato to play such a crucial role in China’s agricultural production and food security.Compared to the yellow or white potato tubers,pigmented potato genotypes contain higher levels of anthocyanins.Anthocyanins have biological functions such as antioxidant activity and can prevent or treat various diseases.Therefore,high anthocyanin pigmented potato cultivars have health-promoting benefits,and studying the accumulation mechanism of anthocyanins is a basic work for the breeding programme of high anthocyanin varieties.In this study,comparisons were employed to analyze the anthocyanin accumulation of potato tubers from two aspects.The main results are as follows:1、Analysis of anthocyanin accumulation in 8 genotypes of colored potato tubers.The qRT-PCR results showed that the anthocyanin biosynthetic enzymes StCHS,StF3 H,StF3’5’H,StDFR,StANS and StGST had significantly higher expressions in pigmented tubers than in non-pigmented tubers,indicating that the differential expression of these six structural genes may be the main cause of the difference in anthocyanin accumulation in colored potato tubers of 8 genotypes.The differential expression analysis and qRT-PCR results showed that transcription factors StAN2,StAN11,StbHLH1,StJAF13 and MYB47415 were much more highly expressed in the purple or red skin and flesh than in yellow or white skin and flesh,which indicated that these five transcription factors may be involved in the regulation of the anthocyanin biosynthesis.Moreover,StbHLH1 was only expressed in pigmented skin and flesh,implying that the specific expression of StbHLH1 may be a limiting factor in controlling tuber anthocyanin biosynthesis.To further understand the regulatory roles of the transcription factors on the enzyme genes,associations between their expressions were investigated.The results showed that the expressions of StAN2,StAN11,StbHLH1,StJAF13,bHLH31926 and MYB47415 significantly correlated with the expressions of CHS,F3 H,F3′5′H,DFR,ANS and GST,suggesting that StAN2,StAN11,StbHLH1,StJAF13,bHLH31926 and MYB47415 may play important roles in anthocyanin synthesis in potato tubers by regulating several key enzymes genes.2、Analysis of light-induced anthocyanin biosynthesis in potao clones FT033-5and FT033-7.By analyzing the expression patterns of genes involved in anthocyanin biosynthesis in light-induced transcripts,it was found that expressions of transcription factors StAN11 and StMYB113 and enzyme genes StCHS,StF3 H,StANS,StDFR and StGST were strongly light-induced,suggesting that StAN11 and StMYB113 may regulate anthocyanin accumulation under light conditions by regulating the expression of these five enzyme genes.The qRT-PCR results reinforced this assumption.The results of transcriptional activation showed that the promoters of StCHS,StDFR,StF3 H,StGST and StANS were significantly activated by StMYB113 and StAN11.Predicting the sequence of a ~2000bp region upstream of the ATG translation start codon of StMYB113 and StAN11 revealed numerous light-responsive elements in their promoters.The sequences of StMYB113 and StAN11 promoters in FT033-5 were aligned with the sequences of StMYB113 and StAN11 promoters in DM,and the results suggested that there were a few mutations in the StAN11 promoter,while more in the StMYB113 promoter,which may be involved in the light-induced expression of StMYB113.