小麦条锈菌无毒基因AvrYr10和AvrYr26的遗传图谱建立与鉴定

Wheat stripe rust is a devastating diseases on wheat in China, seriously threatening safe production of the crop. Growing resistance cultivars is considered the most effective and low cost approach for control of the disease. However, resistance of cultivars were often overcome by new races of the causal pathogen of the wheat stripe rust, Puccinia striiformis f. sp. tritici, due to virulence variation, frequebtly resulting in subsequent epidemics. Recently, studies demonstrated that barberry (Berberis) as alternate host for P. striiformis f. sp. tritici were widely distributed in China and existence of sexual reproduction of the rust pathogen occurred on barberry under natural condtions, and sexual reproduction is an important way for causing virulence variation of the rust pathogen. These new findings make it possible to study on genetics of virulence, identification and cloning of avirulence genes of P. striiformis f. sp. tritici. Therefore, in this study, a progeny population will be made by sexually crossing races of CYR32, avirulent to Yr10 and Yr26, and CYR34, the newest race and virulent to the resistance genes, of P. striiformis f. sp. tritici, and conducted to test their virulence patterns and analyze genome variation regions by sequencing parent races and their progeny based on a combined method of traditional biological approach and genomic sequencing technology. This will help us to reveal genetic mechanism of avirulence genes, AvrYr10 and AvrYr26, of P. striiformis f. sp. tritici, screen molecular markers linked to the two avirulence genes and construct genetic linkage map. The results will provide bases for cloning avirulence genes and understanding pathogenic mechanism of P. striiformis f. sp. tritici as well as reasonable utilization of wheat resistance cultivars, development of new measurement for control of wheat stripe rust and strategy for sustainable management of the disease in China.

小麦条锈病是影响我国粮食安全的重大生物灾害,种植抗病品种是防治该病最为经济有效的措施。然而，条锈菌毒性变异不断产生新小种，导致品种抗病性“丧失”，频繁引发病害流行。近期研究发现条锈菌转主寄主小檗在我国分布广泛、自然条件下条锈菌存在有性生殖，证实有性生殖是条锈菌毒性变异的重要途径。这些新发现使得条锈菌毒性遗传研究、无毒基因定位与克隆成为可能。为此，本项目将传统生物学方法与基因组学技术相结合，以对抗病基因Yr10和Yr26具毒性的新小种CYR34和无毒小种CYR32进行小种间有性杂交，通过对亲本菌系及后代群体的毒性测定与基因组测序分析，以揭示无毒基因AvrYr10与AvrYr26的毒性遗传规律、获得与无毒基因连锁的分子标记、构建无毒基因遗传连锁图谱，为进一步克隆条锈菌无毒基因及揭示病菌致病机理奠定基础，并为我国小麦抗病品种合理利用、条锈病防控新技术研发以及病害持续控制策略的制定提供科学依据。

小麦条锈病是影响我国粮食安全的重大生物灾害,种植抗病品种是防治该病最为经济有效的措施。然而，条锈菌毒性变异不断产生新小种，导致品种抗病性“丧失”，频繁引发病害流行。近期研究发现条锈菌转主寄主小檗在我国分布广泛、自然条件下条锈菌存在有性生殖，证实有性生殖是条锈菌毒性变异的重要途径。这些新发现使得条锈菌毒性遗传研究、无毒基因定位与克隆成为可能。. 本项目将传统生物学方法与基因组学技术相结合，以对抗病基因Yr10和Yr26具毒性的新小种CYR34和无毒小种CYR32进行小种间有性杂交，通过对亲本菌系及后代群体的毒性测定与基因组测序分析，以揭示无毒基因AvrYr10与AvrYr26的毒性遗传规律、获得与无毒基因连锁的分子标记、构建无毒基因遗传连锁图谱。本项目通过小麦条锈菌小种间有性杂交构建了后代群体221个，表型鉴定表明，AvrYr26和AvrYr10上无毒位点与毒性位点的分离比约3:1，表明每一个无毒位点由一个显性基因独立控制，该位点的遗传符合孟德尔遗传规律。基于基因组测序，组装了亲本菌系CYR32的基因组并进行了注释。通过集团分离分析法（BSA），经过SNP和InDel 的变异检测和注释，过滤掉低质量可信位点。利用欧氏距离(ED)算法、SNP-index和InDel-index算法进行关联分析, 确定SNP和InDel对应的交集区域，最终将无毒基因AvrYr10和 AvrYr26的候选区间定位到缩小到Lachesis group13染色体的1个候选区域内，总长度为0.02 Mb。并绘制遗传图谱。研究结果为后续研究条锈菌基因组的结构、功能、群体进化、关键致病基因定位以及克隆奠定基础；对揭示病菌毒性变异的分子机制具有重要意义。