小麦条锈菌有性过程在毒性变异及病害流行中的作用研究

wheat stripe rust,caused by Puccinia striiformis f. sp. tritici, is one of the most destruvtive diseases of wheat in wheat-growing areas in China and the world. The disease cause huge yield losses in the epidemic years because the resistances of wheat cultivar overcome by new virulent races of P. striiformis generated by virulence variation. However, the sexual stage of the pathogen has not been found in the past, resulting in lack of understanding on the role of the sexual stage in complete life cycle and virulence variation of the pathogen. Up to date, foregin pathogenists identified that barberry (Berberis spp.) is alternate host of P. striiforms in indoor experiment conditions. This is to provide a basis for revealing the role of barberry as alternate host of P. striiformis in life cycle and disease development in China. Therefore, this study is to identify the species and geneoraphic distribution of barberry as alternate host of P. striiformis in "hot-spot" areas of wheat stripe rust based on investigation of B. spp species in nature, inoculation on B. spp. plants with germinating teliospores, and the recombined methods of biological and micorbioloigcal techniques. Also, the aim of the study is to uncover characters of sexual reproodductiion, and role of B. spp. as alternate host of P. striiformis and race dynamics of P. striiformis races in China. These will be helpful for further understanding the reason of "variable area" of P. striiformis in China, and providing technique support for making strategies for sustainable controlling wheat stripe rust using gene deployment of wheat cultivars.

小麦条锈病在我国分布广、流行性强、危害和损失严重，原因之一是病菌毒性变异频繁致使品种抗病性丧失。条锈菌有性繁殖过程过去一直未被发现，导致其在病菌生活史及毒性变异中的作用不明。近期国外学者通过室内接种发现条锈菌可侵染小檗完成有性过程，这为揭示我国条锈菌生活史和小檗转主寄主在病害循环中的作用提供了依据。因此，本项目拟在前期调查、接种小檗的基础上，结合传统生物学方法与分子生物学技术，调查明确我国小檗的主要种类及其分布情况；揭示自然条件下我国小麦条锈菌转主寄生、有性繁殖的特征与规律；明确有性繁殖在病菌生活史和在病害循环中的作用；进而探索其在我国条锈菌毒性变异中的作用以及与主要流行小种演变的关系等问题，为进一步解析我国小麦条锈菌毒性变异"易变区"的成因奠定理论基础，进而为小麦条锈病防治技术的研发、可持续控制策略制定、小麦抗病品种合理利用等提供科学依据。

小麦是我国主要的粮食作物，条锈病是我国及世界其他国家小麦上重要生物灾害，其流行危害严重，原因是病菌毒性变异频繁致使品种抗病性丧失。条锈菌有性繁殖一直未被发现，导致其在病菌生活史及毒性变异中的作用不明。近期年人工接种发现条锈菌的有性生殖，这使得开展有性生殖的相关研究成为可能。因此，本项目围绕小檗资源调查、转主寄主鉴定、有性生殖与毒性变异等开展了研究，以期揭示自然条件下我国小麦条锈菌转主寄生、有性繁殖的特征与规律；明确有性繁殖在病菌生活史和在病害循环中的作用；进而探索其在我国条锈菌毒性变异中的作用等问题，解析我国小麦条锈菌越夏"易变区"的成因，为小麦条锈病防治技术的研发、可持续控制策略制定、小麦抗病品种合理利用等提供科学依据。取得了以下结果：.1.调查我国14个省份分布有35种小檗; 建立了小麦条锈菌转主寄主鉴定方法；确定了28种小檗是小麦条锈菌的转主寄主。.2.在国际上首次获得了我国自然条件下条锈菌有性生殖常年发生的直接证据，完善了小麦条锈菌生活史和病害流行体系。四个年份从6种不同小檗上分离获得小麦条锈菌菌系134个，60个为当前流行的小种，其余74个为新的小麦条锈菌小种。.3.揭示系统揭示了小麦条锈菌致病性变异规律与机理；揭示有性生殖是条锈菌毒性变异的主要途径。 .4.揭示了条锈菌有性阶段侵染与发育的组织学与细胞学特征；发现了冬孢子产生次生后担子的生物学现象，为相关研究提供了重要理论依据。.5.为小麦条锈病防治新策略的制定提供了科学依据。