利用看家基因SNP解析云南小麦条锈菌群体遗传结构

Wheat stripe (yellow) rust is one of the most important epidemics which threaten wheat security severely. Yunnan is a district where stripe rust breaks out constantly, it is one of the fewer regions in China where the pathogen can over summer and winter and the pathogen is very complex. Yunnan has the important characteristics of original pathogen base of stripe rust and prerequisite of pathogen migrating for long distance. It's very important to know the population genetic structure of stripe rust pathogen in Yunnan before answering the relationship of pathogen between Yunnan and other epidemic regions, because it is the most effective method to reveal the origin, evolution and migration of pathogen. Single neucleotide polymorphism (SNP) is a new technique of multilocus population analysis based on DNA sequence.It has a high frequency in fungi genome and can be detected easily, and has higher precision and reliability than DNA fingerprint and spend little time. SNP has been used for researching the origin, evolution and gene flow of plant pathogen gradually and has succeeded in population genetic research of powdery mildew pathogen in America. Because house-keeping genes can express stably in all of cells,so this project we will analyse the population genetic structure of stripe rust pathogen in Yunnan by SNP of house-keeping genes such as NCS1, MAPK1, β-tublin1, Cdc2 of Puccinia striformis f.sp. tritici and Ef-1α of Puccinia graminis f.sp. tritici for the first time, to reveal the origin, evolution and migration of Puccinia striformis f.sp. tritici deeply. And confirm the results by pathogen virulence evolution in space and time and disease occurred time order in fields.

条锈病是严重威胁小麦安全生产的重大流行性病害，云南是条锈病的重发区，是我国条锈菌能顺利越夏越冬及毒性最复杂的少数地区之一，云南具有初菌源地的重要特征及远距离传播的必备条件，在回答云南小麦条锈菌与其它流行区的关系之前，系统认识其群体结构，迫切重要，这是揭示其起源、进化及传播最有效的途径。单核苷酸多态性（SNP）是基于DNA序列的新一代多位点种群分析技术，在真菌基因组中发生频率高，易检测到，其精度和可靠性较DNA指纹技术高且省时，已逐渐用于植物病原真菌起源、进化及基因漂移等研究，并在美国成功用于小麦白粉菌群体遗传研究。看家基因由于在所有细胞中能稳定表达，本项目首次采用小麦条锈菌看家基因NCS1、MAPK1、β-tublin1、Cdc2和秆锈菌看家基因Ef-1α等SNP解析云南小麦条锈菌群体遗传结构，深入揭示其起源、进化及传播。同时辅以病菌毒性的时空演化及病情发生的时间序列予以印证。

条锈病是世界性的严重威胁小麦安全生产的重大流行性病害。本项目利用小麦条锈菌看家基因的SNP技术，解析云南小麦条锈菌群体遗传结构，并辅以病菌毒性监测及病情发生的时间序列予以印证。通过项目实施，利用GeneBank小麦条锈菌看家基因的序列，设计引物，开发出7个看家基因的SNP引物。采用Cdc2, Ef-1α, Mapk1, Hsp, Uba及Ubc等6个看家基因，对云南11个地区的352个菌株进行SNP分析，结果揭示了云南小麦条锈菌群体具有丰富的单倍型（220个），非常高的遗传多样性（Hd=0.946 ~ 0.993）、群体变异率（3.34E-03 ~ 5.98E-03）及重组事件（6 ~ 11）。云南群体内遗传分化低，基因流高（Nm=18.45）。祖先单倍型出现在玉溪，玉溪与临沧间存在高强度的基因流。结合条锈病发生流行的时间序列及云南常年盛行西南风，推断临沧及周边地带为云南其它麦区提供外来菌源。为明确云南和陇南条锈菌群体的关系，采用Mapk1、Cdc2和Ef-1α的连接基因，对2008及2011年共297个菌系进行SNP分析。由祖先单倍型来自云南，云南和陇南群体具有高频率的共享单倍型及高强度的基因流，结合高空气流的轨迹多由云南指向陇南，表明了陇南的条锈菌起源于云南。生理小种及毒性研究揭示当前云南小麦条锈菌小种主要以CYR32及CYR33为代表的Hybrid 46和水源11致病类群为主。条锈菌群体对Yr5,Yr10,Yr15及Yr32的毒力频率均为0，对Yr24, YrTr1,Yr8及Yr17的毒力频率为0.74% ~ 11.76%。对Yr27的毒力频率为52.94%，对Yr1,Yr6,Yr7,Yr9,Yr43,Yr44,YrSP,YrExp2,YrTye的毒力频率为77.94% ~ 91.91%。项目研究结果，为云南小麦条锈菌的起源和传播提供了线索，并探索了云南是否为我国小麦条锈菌初菌源地，这对我国小麦条锈病的源头治理、小麦抗病育种及抗病基因合理利用, 具有重要的指导意义。项目发表核心期刊论文2篇，培养博士2名，指导1名孟加拉国青年科学家开展锈病研究，2人职称晋升。