Isolation And Characterization Of STAN11and STAN1B Genes Related To Anthocyanin Biosyntheseis Regulation In Potato

Anthocyanins are the major pigments responsible for the potato tubers color. In plants, the anthocyanin biosynthesis genes are tightly regulated by three classes of regulatory factors, MYB, bHLH and WD40. The biochemical pathway and genetic control of anthocyanin production is well characterized in numerous plant species and is considered to be conserved among different species in the plant kindom. In potato, StAN11gene encoding a WD40-repeat protein is a homologue of AN11in Petunia and TTG1in Arabidopsis which were shown to be involved in anthocynin biosynthesis regulation. While study on bHLH TF in potato have not been reported. In this study, two regulatory genes StAN11and StAN1b were isolated from Chieftain and Desiree by RT-PCR and the function of StANll was then analyzed. The results are as follows:1. StANll from Chieftain was inserted behind the CaMV35S promoter of pCMBIA1304. Recombination vector was introduced into the potato cultivar Desiree plants by Agrobacterium-mediated transformation. The6transgenic lines overexpressing the StANll gene were identified by genomic PCR analysis from Hygromycin B-resistant plants. The anthocyanin content and the color of transgenic potato tubers was found to be improved significantly compared to the wild potato tubers. Due to the overexpression of StAN11, the transcript levels of the anthocyanin biosynthesis structural gene StDFR was also up-regulated, while the expressions of StF3H, StANS and St3GT were similar. These results suggest that StAN11may regulate anthocyanin biosynthesis by modulating its target gene DFR.2. StAN1b was isolated from the potato cultivar Desiree by RT-PCR. The open reading frame of the gene was1896bp long and encoded a putative protein of631amino acids with a molecular weight of69.39kDa and a theoretical pI of5.00. The multiple alignment of the amino acid sequence of StAN1b and that of other homologues showed that StAN1b had a high identity with homologous member from Solanum lycopersicum. Analysis of StAN1b mRNA level by semi-quantitative RT-PCR showed that it was expressed in leaves, buds and tuber skins but rarely be detected in roots and stem, while it is weaker in the stolons.