论文部分内容阅读
Peach was frequently observed to bear different colors of flowers on the same tree.Yet the genetic mechanism underlying this attractive phenomenon has not been completely elucidated.We sequenced and analyzed the key structural genes in the anthocyanin biosynthesis pathway, and found that the ANS gene of white flower contained a 129bp sequence that lacked in pink petals, which resulted in a deficient ANS protein in the white petals due to intron retention.ANS protein is a 2-oxoglutarate (2OG) iron-dependent oxygenase enzyme responsible for the transformation of the colorless leucopelargonidin or leucocyanidin into the colored pigments.Homology modeling of the white and pink ANS revealed that inton retention caused the loss of FE 2∶1 ligand in the white ANS, thereby diminished its affinity to ferricion, which eventually led to the dysfunction of the translated protein.In accordance to this finding, we detected extremely low level of cyanidin-based anthocyanin and virtually no pelargonidin-based anthocyanin in white petals by HPLC and LC/MS analyses.As a consequence, dysfunction of white ANS would result in the accumulation of colorless leucopelargonidin and leucocyanidin and block the conversion of substrates for the downstream enzymatic proteins, which in turn suppress the expression of the flavonoid biosynthesis genes in white petals.This speculation was verified by the results of qRT-PCR analysis in our study.