PpSUT5信号系统在桃果肉花色素苷合成通路中的作用及机理分析

In recent years, the anthocyanin was paid more and more attention by researchers because it can make fruit to be colorful and supply nutrition and disease therapy for human beings. Peach is the model species for studying molecular biology in Rosaceae family, and also have many type of red flesh traits. Then it was reckoned suitable material to study the regulatory networks of anthocyanin synthesis. Based on the current progress of red flesh trait, the key gene were found to be located in linkage group 1, 3, 4 and 5 through linkage analysis. However, only the genes located on linkage group 3 and 5 have been identified in peach. Therefore, a genome-wide association study and expression experiment were carried in peach to resolve the more comprehensive pathway of anthocyanin biosynthesis. The result showed that a gene, PpSUT5, which associated with red flesh and encoded sugar transporter protein, was thought as a key gene in the QTLs of linkage group 1. To further verify PpSUT5 function, the project intends to first confirm the inducing effect of sugar on anthocyanin accumulation by different sugar incubated peach flesh in vitro, and then the relationship between this effect and PpSUT5 was analyzed. Secondly, the function of PpSUT5 was verified through RNA interference and overexpression experiment. Finally, a yeast two-hybrid system was used several rounds to identify the proteins interacting with PpSUT1. The study is helpful to explore the key gene of red flesh traits in peach, dissect the molecular mechanism of anthocyanin synthesis which induced by sugar signal, and thereby accelerating the molecular breeding process of peach with red flesh.

花色素苷是果实呈现红色的重要原因，近年来因其在营养保健方面的作用而备受关注。桃是蔷薇科果树分子生物学研究的模式树种，红肉类型各异，适宜进行花色素苷调控网络的研究。利用不同群体，研究者将桃红肉性状定位在第1、3、4和5连锁群，而只有定位于第3和5连锁群上的关键基因得到鉴定。申请者通过对桃红肉性状进行全基因组关联和表达分析，在第1连锁群的关联区段内发现了1个编码糖转运蛋白的红肉性状关键候选基因PpSUT5。为进一步探索PpSUT5的功能和作用机理，本项目拟首先用不同类型糖温育桃果肉圆片，体外证实糖对花色素苷积累的诱导效应，并分析这种效应与PpSUT5的关系；进而通过瞬时干扰和超表达PpSUT5研究验证其功能；最终，利用多轮酵母双杂体系鉴定与PpSUT5互作的蛋白。本项目为发掘桃红肉性状关键基因、解析糖诱导花色素苷合成的信号通路，加速红肉桃育种具有重要意义。

花色素苷是果实呈现红色的重要原因，近年来因其在营养保健方面的作用而备受关注。桃是蔷薇科果树分子生物学研究的模式树种，红肉类型各异，适宜进行花色素苷调控网络的研究。在前期研究中，研究者将桃红肉性状定位在第1、3、4和5连锁群，而只有定位于第3和5连锁群上的关键基因得到鉴定。申请者通过对桃红肉性状进行全基因组关联和表达分析，在第1连锁群的关联区段内发现了1个编码糖转运蛋白的红肉性状关键候选基因PpSUT5。为进一步探索PpSUT5的功能和作用机理，本项目首先用12份材料为试材，采用荧光定量PCR方法验证了17个PpSUT基因的表达，发现花色素苷合成候选基因PpSUT5在白凤和郑白5-2的果实发育早期有显著表达，随着果实发育，该基因呈下降趋势，直至果实成熟；而在郑引82-9、天津水蜜和中桃红玉的果实发育后期有一定的上调表达，与花色素苷含量一致。研究进而用不同类型糖温育桃果肉圆片，发现而在红肉桃中，葡萄糖、蔗糖、山梨醇均能诱导花色素苷合成，果糖没有诱导作用，而松二糖和3-氧甲基葡萄糖甚至具有抑制作用。实验进而通过瞬时转化PpSUT5基因，却没有发现花色素苷有明显变化，因此该部分工作需要继续研究。最后，通过构建一个核体系的表达文库，利用酵母双杂实验表明PpSUT5与Prupe.1G243900、Prupe.1G364200和Prupe.5G117900互做。本项目为发掘桃红肉性状关键基因、解析糖诱导花色素苷合成的信号通路，加速红肉桃育种具有重要意义。