小麦抗赤霉病主效QTL Fhb1位点上抗病候选基因TaRLK-B功能分析

Fusarium head blight (FHB) or scab is an important disease of wheat in warm and humid regions which is a serious threat to grain yield, quality and food safety. Selection of wheat cultivars resistant to FHB is the most economical and effective means for disease control. However, research on cloning of resistance related genes and characterization of molecular resistance mechanism is quite limited. In the previous research, by fast neutron irradiation, a mutant namely NAUH117 from Wangshuibai with increased FHB susceptibility, and the mutant had a 3BS chromosome fragment deletion including the Fhb1 region. Gene expression profiling for Wangshuibai and NAUH117 when induced by F. graminearum were abtained and compared in the investigation of pathways and genes associated with FHB resistance. A receptor-like kinase gene TaRLK-B from Wangshuibai was cloned as resistant candidate gene for Fhb1. In the proposed research, the function of TaRLK-B in resistance to FHB will be analyzed. We study the relationship between gene structure and the function by cloning the TaRLK-B homolog genes from species of different resistant levels. We will also study the gene expression patterns for TaRLK-B from these different wheat varieties in the survey whether this gene is specificly induced under pathogen infection in the resistant genotypes. The function of TaRLK-B in resistance to FHB will be finally analyzed by over-expression via transformation and gene silencing using VIGS,etc. The objective of the work is (1) to characterize this TaRLK-B gene in the role of resistance to FHB; (2) to provide new resistant gene resource which has the potential use in enhancement of wheat resistant to FHB and (3) to develop molecular marker for marker-assisted selection.

赤霉病是危害小麦安全生产的重要病害之一。种植抗病品种能够有效经济的控制病害发生，但常规育种进展缓慢。克隆抗赤霉病关键基因，研究抗病分子遗传机理，将其应用到小麦分子育种中，对于加速育种进程具有重要的理论指导和现实意义。本实验室在前期构建了抗赤霉病小麦地方品种望水白及其Fhb1缺失的感病突变体受赤霉菌诱导的基因表达谱，筛选并克隆到一个Fhb1位点上的抗病候选基因TaRLK-B。本项目拟以该基因为研究对象，利用同源克隆、关联或连锁分析等研究TaRLK-B序列特征与Fhb1位点及抗病功能的关系；在不同抗感小麦品种中对TaRLK-B等位基因进行表达分析，研究其表达特征与功能的关系；利用瞬时沉默以及转基因等功能验证，明确该基因在抗赤霉病过程中的作用及其介导的抗病信号通路。预期研究成果可为抗赤霉病育种提供新的基因资源和分子标记，并丰富抗赤霉病分子机制理论。

赤霉病是危害小麦安全生产的重要病害之一。种植抗病品种能够有效经济的控制病害发生，但常规育种进展缓慢。克隆和验证抗赤霉病关键基因如Fhb1，对于解析小麦的抗赤霉病分子机理，并应用到小麦抗病分子育种中，加速育种进程具有重要的理论指导和现实意义。本项目前期利用望水白Fhb1缺失的感赤霉病突变体（Xiao et al., 2011），并利用基因芯片、数字基因表达谱等组学手段，结合染色体定位信息，筛选Fhb1位点的抗病候选基因（Xiao et al., 2013）。本项目对Fhb位点上的一个抗病候选基因，即类受体蛋白激酶基因TaRLK-B进行序列特征分析、表达特征分析和功能验证，并开发了基于SNP的分子标记。分析该基因的基因组序列组成，发现TaRLK-B在抗（或HRC+）、感（或HRC-）赤霉病小麦品种中有单倍型差异，为一个G的插入或缺失，“G-”单倍型只存在抗赤霉病小麦品种（或HRC+）中；“G+”单倍型只存在感赤霉病小麦品种（或HRC-）中；对其表达的时空特征进行了分析，表达情况跟抗、感品种有显著相关性，即只在抗病品种中（或HRC+）表达，且受诱导，在感病品种中（或HRC-）检测不到表达，暗示不同TaRLK-B单倍型与抗、感小麦品种存在关联；利用实验摸索并建立起来的小麦穗部的瞬时基因沉默手段（VIGS）表明，瞬时沉默TaRLK-B，小麦感病性明显提高，多年多点的转基因功能互补实验表明，小麦品种扬麦158转TaRLK-B基因可以明显提高植株的赤霉病抗性，验证了该基因的功能，同时创制抗赤霉病的小麦转基因材料；基于SNP点开发了分子标记，在重组自交系群体和自然群体进行标记分析和抗赤霉病的连锁或关联分析，表明可用于分子标记辅助选择。本研究表明TaRLK-B是Fhb1位点上的关键抗病基因，可为小麦抗赤育种提供了有利用价值的抗病基因资源，同时开发的一个SNP分子标记，可应用于抗赤霉病分子标记辅助选择育种。