花烟草自交不亲和可塑性关键基因的转录调控机制研究

自交不亲和(SI)物种改变SI强度结实的现象称为自交不亲和可塑性（PSF)，PSF对植物繁衍和进化至关重要，其调控机制尚不清楚。我们筛选获得有PSF表型的花烟草，伴随其雌蕊衰老，SI强度减弱并结实，在调控PSF中发挥主要功能的基因120kDa和ht-b表达下调；雌蕊衰老后，水杨酸（SA）含量降低，花冠喷施SA增强SI，且ht-b启动子含SA响应元件，表明SA可能参与花烟草PSF调控。本项目拟探究DNA和组蛋白（H3K27me3）甲基化（抑制基因表达）是否参与120kDa和ht-b伴随雌蕊衰老的下调表达调控；开展PSF关键基因启动子对SA的响应性实验，构建内源SA降解及抑制SA转化的突变体，探究SA是否影响PSF关键基因的转录，及其参与PSF调控的机制。本研究将促进对PSF调控机制及SA和表观遗传修饰在授粉受精中的功能认识，对具有PSF繁殖方式的植物繁种，杂种优势利用育种实践有重要指导意义。

Pseudo-self-fertility (PSF) refers to that the self-incompatibility (SI) species set fruits by quantitative variations in the SI strength, and was important for species reproduction and evolution. The regulatory mechanisms of PSF are unclear. Previously, a line of N. alata (S6S6) with typical PSF phenotype was screened out, in which SI strength was weaker and fruits were set during the pistil senescence. The expression levels of 120 kDa and ht-b were decreased during the pistil senescence，and they were the key genes regulating PSF. In addition, the contents of salicylic acid (SA) declined during the pistil senescence, and the application of external SA to the flower enhanced the SI strength, and there were SA responsive element in the promoter of ht-b, revealing that SA might regulate PSF. Based on the reports that DNA and H3K27me3 methylation modification suppress gene expression，we will explore whether they were associated with the down-regulated expression of 120 kDa and ht-b during the pistil senescence. In addition，the responsiveness of the ht-b promoter to SA was tested，the endogenous SA degraded and over-accumulated mutants were constructed, to clarify whether SA regulated the expression of SI related genes，and explore the regulatory mechanisms of SA in PSF. This project will deepen our understanding of the regulatory mechanisms of PSF and the function of SA in pollination and fertilization，and is significant for guiding the reproduction and breeding practice of heterosis utilization in PSF species.