小麦寡聚糖转移酶催化亚基基因TaSTT3b的抗纹枯病功能与分子机制研究

Wheat sharp eyespot is one of soil-borne fungi diseases that affect wheat production in China. The mechanisms underlying wheat resistance to Rhizoctonia cerealis are poorly understood. In our previous study, TaSTT3b, which encodes a catalytic subunit of the oligosaccharyltransferase complex, was identified via RNA-seq, qRT-PCR, combined with BSMV-VIGS analysis. TaSTT3b has higher expression level in R. cerealis-resistant wheat than in R. cerealis-susceptible wheat, and silence of TaSTT3b in R. cerealis-resistant wheat reduced the resistance to R. cerealis. In this proposal, we plan to perform the following researches: to isolate the full-length sequences of TaSTT3b from various resistant- and susceptible-wheat cultivars and analyze the spatiotemporal expression characteristics; to study the biological function of TaSTT3b in wheat overexpressing and underexpressing TaSTT3b generated by transgenic and BSMV-VIGS techniques. The transgenic wheat were then used to study the gene networks regulated by TaSTT3b by using RNA-seq and qRT-PCR, and to identify the target proteins of TaSTT3b-dependent glycosylation using immunoblot and LC-MS/MS techniques. Finally reveal the molacular mechanism of TaSTT3b underlying wheat resistance to R. cerealis. This project will contribute to uncover the resistance network in wheat response to sharp eyespot, and provide resistant gene resource for wheat resistance molecular breeding.

小麦纹枯病是影响我国小麦生产的土传真菌病害之一。目前，关于小麦对纹枯菌的抗性机制尚不明确。本课题在前期工作中，通过转录组测序、荧光定量PCR，结合BSMV-VIGS实验，鉴定出一个寡糖基转移酶催化亚基编码基因TaSTT3b，该基因在抗纹枯病小麦中具有较高的表达量，且其在抗病小麦中的表达沉默显著降低了其对纹枯病的抗性。本项目将从抗、感纹枯病小麦中克隆TaSTT3b基因全长序列，分析其时空表达特性；通过创制过表达（转基因）和沉默表达（VIGS）小麦研究TaSTT3b的抗病生物学功能。进而以转基因小麦为实验材料，利用转录组测序、荧光定量PCR等技术研究TaSTT3b调控的基因网络；综合应用蛋白质免疫印记和LC-MS/MS等分子生物学方法，鉴定TaSTT3b介导的糖基化修饰的靶蛋白，解析TaSTT3b抗病作用的分子机理。该项目将有助于揭示小麦对纹枯病的抗性反应网络，为小麦抗病育种提供优异基因资源。

小麦纹枯病是影响我国小麦生产的土传真菌病害之一。目前，关于小麦对纹枯菌的抗性机制尚不明确。本研究通过转录组测序、荧光定量PCR，结合BSMV-VIGS实验，鉴定出一个寡糖基转移酶催化亚基编码基因TaSTT3b，该基因受纹枯菌诱导表达，且在抗纹枯病小麦中具有较高的表达量。本项目从抗、感纹枯病小麦中克隆了TaSTT3b基因全长序列，明确了其时空表达特性。转基因过表达TaSTT3b基因显著增强了小麦对纹枯病的抗性，而沉默该基因的表达减弱了对纹枯病的抗性。转录组测序分析揭示了TaSTT3b调控的基因网络，鉴定到1751个上调的差异表达基因，并且TaSTT3b能够促进类黄酮的合成。该研究还发现TaSTT3b促进茉莉酸的合成，茉莉酸预处理能够恢复TaSTT3b基因沉默引起的抗病性减弱，这说明TaSTT3b介导的小麦对纹枯病的抗性依赖于茉莉酸信号路径。另外，我们还发现，过表达TaSTT3b基因能够通过影响高分子量麦谷蛋白亚基编码基因和蔗糖合酶编码基因的转录水平，显著增加籽粒粒宽、粒长和千粒重。以上结果解析了TaSTT3b抗病作用的分子机理，将有助于揭示小麦对纹枯病的抗性反应网络，为小麦抗病育种提供优异基因资源。