小麦抗茎基腐病优异种质资源筛选和抗病位点发掘

Crown rot (CR), caused by Fusarium species, is one of the most persistent soil-borne diseases of wheat world-wide. Diseased plants are characterized by a honey-brown discoloration in the leaf sheaths and lower stem, necrosis of crown region, and formation of white heads, in which little or no grain is formed. Since its first identification in Australia in 1966, nowadays CR occurs in most cereal regions in the world, including Australia, Europe, North America, South America, West Asia etc., resulting in a big yield and economic loss. Recently, the incidence and severity of CR was progressively increased in major winter growing provinces in China. In 2016, the diseased field ratio in Henan province was 65.1%, with a yield reduction at 51.6% in some areas. In 2015, the highest field white head ratio in Hebei province was 50%..One of the key measures in effectively managing CR damage is growing resistant and tolerant varieties. To date, a few wheat genotypes with partial resistance to the disease have been identified globally. The QTLs conferring CR resistance have been reported on 13 chromosomes in hexaploid wheat. In contrast, limited efforts have been made in identifying resistant local germplasms in China. Study indicated that all of the 88 elite varieties in Huanghuai Plain investigated in the study are susceptible to CR. Similarly, no genetic studies of CR resistance have been performed yet. Therefore, to control the spread and damage of CR in China, the identification of wheat germplasms adapted to China and investigation of QTL/genes associated with CR resistance in local germplasms is urgently needed..To solve these problems, this study is: 1) to select 600-700 representative germplasms from Chinese winter wheat accessions collected by China Agricultural University, and assess their resistance to CR, 2）based on resistant performance to CR, to further select 400 germplasms for genome-wide association mapping, using Illumina 90K ISelect SNP chip and flanking molecular markers of known QTL, to investigate the potential novel and known QTL as well as their distributions in Chinese winter wheat population, to identify the SNP markers associated with CR resistance and the candidate genes, and 3) to confirm the functions of candidate genes by gene expression analyses and plant transformation etc. The results from this study will lay a solid foundation for improvement of CR resistance in Chinese wheat breeding programs.

小麦茎基腐病是镰孢菌属真菌引起的土传病害。鉴于该病害在我国蔓延和危害不断加重，小麦育种中存在着抗源种质材料甚少、已有抗病QTL在自然群体中优异等位变异不明、新的抗病位点发掘不够、抗病基因缺乏等亟待解决的理论和技术问题，本研究拟对全国不同生态区5000份品种资源，按照系谱及地理来源等综合评价基础上筛选出600-700份代表性材料，并进行抗病性鉴定，发掘适于我国生态环境的一批抗源材料；结合抗性表型数据，进一步筛选400份核心资源构建关联群体，利用小麦SNP芯片和已发现的3BL等主效抗病QTL两翼分子标记进行基因型检测，分析已知QTL在我国小麦品种中的等位变异及分布，发掘新的抗病位点及SNP标记；研究重要候选基因表达规律，解析基因抗病功能及作用机制。本研究将拓宽我国小麦抗茎基腐病种质材料和基因资源，增添新的抗病分子标记，丰富小麦抗茎基腐病的遗传基础，为我国小麦抗病育种提供科学依据。

小麦茎基腐病是镰刀菌属真菌引起的我国小麦生产新发土传病害。本项目围绕茎基腐病抗源筛选、抗病位点和抗病基因发掘开展了一系列研究。对具有代表性的670份我国小麦种质资源茎基腐病进行抗性鉴定，筛选出15份农艺性状优良、抗性表现稳定的抗源种质材料。发明了一种新的茎基腐病鉴定方法。构建了自然群体，通过全基因组关联分析发现了104个与茎基腐病抗性紧密关联的 SNP位点。这些位点分布于1BS, 1DS, 2AL, 5AL, 5DS, 5DL, 6BS 和7BL等染色体上。其中，位于 5DS，1BS和2AL上的SNP位点为已知位点，5DL位点为新位点。针对5DL位点开发了高通量KASP分子标记。根据基因结构和注释，预测了5DL抗茎基腐病新位点的可能候选基因，比较分析了这些候选基因在抗、感材料接种后多个时间点的表达情况。通过抗、感材料接种后蛋白组和代谢组分析，发掘了一批可能与茎基腐病抗性紧密相关的关键蛋白和代谢物，为候选基因发掘和抗病机制解析奠定了理论基础。创建了5DL抗性新位点可能候选基因的过表达和编辑材料，初步明确了重要候选基因的抗病功能。项目研究结果为我国小麦茎基腐病遗传改良提供了重要的材料和理论依据。