PubHLH94调控南果梨及其芽变果实蔗糖积累差异的分子机理

高糖是梨育种的一个重要目标。‘南红梨’是‘南果梨’的高糖积累芽变，申请人前期发现‘南红梨’具备更高蔗糖含量和PuSUT-like表达量，但未在两品种中发现PuSUT-like全长和启动子序列差异。表达差异最大的转录因子PubHLH94可与PuSUT-like启动子结合，但其调控机理尚未明确。基于此，本研究拟利用农杆菌介导的果实中瞬时过表达和沉默PuSUT-like，验证其是导致‘南红梨’积累高蔗糖的关键基因；采用ChIP-PCR和GUS报告基因等方法，研究PubHLH94如何调控PuSUT-like转录；通过分析PubHLH94差异表达的原因，明确‘南红梨’与‘南果梨’果实中蔗糖积累差异的分子机理；最终在梨果实中瞬时过表达和沉默PubHLH94，明确其在‘南红梨’积累高蔗糖过程中的作用。本项目的实施对深入解析梨果实糖分积累机制、品种改良和品质调控具有重要的理论意义。

Improving the sugar content of pear fruit is a major goal in horticultural crop breeding. Nanhong is a high sugar accumulation bud sport of Nanguo. In our previous study, we measured the sugar content in Nanguo and Nanhong pear fruits and found that the sucrose content was higher in Nanhong. We compared the transcriptomes of the two varieties using RNA-seq and identified a sucrose transporter gene, PuSUT-like, as being expressed at higher levels in Nanhong fruit. To elucidate the PuSUT-like expression profiles in Nanguo and Nanhong fruits, we compared the PuSUT-like CDS from each; however, no difference was found. Moreover, no differences were observed in the promoter of PuSUT-like. A bHLH transcription factor PubHLH94 which was expressed at higher levels in Nanhong fruit could bind the promoter of PuSUT-like. However, the underlying mechanism of which sucrose levels can be elevated is still unclear. Based on these results, overexpression and silencing of PuSUT-like in pear fruit will be carried out to identify if the gene is essential for sucrose accumulation in pear fruit. Then, ChIP-PCR and GUS Reporter System experiments will be used to further clarify the transcriptional regulation model of PubHLH94 on PuSUT-like. Elucidating the PubHLH94 expression profiles in Nanguo and Nanhong pear fruits. Finally, overexpression and silencing of PubHLH94 in pear fruit will be carried out to clarify the gene function of how PubHLH94 regulating sucrose accumulation in pear fruit. Our research will be useful for understanding the mechanism underlying the sugar accumulation and providing evidence for creation of pear germplasm and regulation of fruit quality.