胶锈菌与寄主协同进化中专化性选择机制形成的分子解析

The rust caused by Gymnosporangium is one of the major fungal diseases of apples and pears, which is a serious obstacle to the healthy and sustainable development of fruit industry in China. At present, the basic theoretical studies on the pathogenic mechanism and interaction between Gymnosporangium and its host are very scarce, which restrict the implementation of disease prevention and control. During the process of studying the relationship between classification and phylogeny of Gymnosporangium, the applicant discovered that spores from different rust species (G. yamadae and G. asiaticum) can infect the same gymnosperm plant (Juniperus chinensis) after germination, but the basidiospores of two species from the same species of Juniperus chinensis have a great differentiation on infection of apple and pear, respectively, which indicates that the Gymnosporangium species has a special selection mechanism in the process of invading the host. In this study, the applicant intend to combine affinity chromatography and high-throughput sequencing technology to establish the gene library of the haustoria in different life cycle stages of G. yamadae and G. asiaticum as well as explore the gene expression patterns in different stages of growth and development of G. yamadae and G. asiaticum by bioinformatics. It is very important to reveal the biological mechanism of interaction between Gymnosporangium species and its host, to further clarify the mechanism of co-evolution and the cause of specific parasitism, and to provide theoretical support for the disease control.

由胶锈菌引起的锈病是苹果和梨减产的主要真菌病害之一，成为制约我国林果业健康持续发展的严重障碍。目前关于胶锈菌致病机制及其与寄主互作等方面的基础理论研究非常匮乏，制约着病害防治工作的开展。申请者在研究胶锈菌属分类与系统发育学关系的过程中发现，来源于不同种（山田胶锈菌和亚洲胶锈菌）的锈孢子在萌发后可以侵染同一裸子植物（圆柏），而源于同一圆柏的两个种的担孢子又产生很大的分化，分别侵染其转主寄主苹果和梨，预示胶锈菌在侵入寄主的过程中有着特殊的选择机制。本研究利用亲和层析技术和高通量测序技术相结合，建立山田胶锈菌和亚洲胶锈菌不同生活史阶段吸器的基因文库，进而通过生物信息学探究山田胶锈菌和亚洲胶锈菌不同生长发育阶段基因表达模式，揭示胶锈菌与寄主互作的生物学机制，对进一步明确胶锈菌与寄主协同进化的机制和专性寄生的原因等基础研究有非常重要的价值，且对于其病害控制提供理论支撑。

本项目运用高通量测序手段结合组织病理学观察及相关实验，对包括山田胶锈菌（Gymnosporangium yamadae）在内的3种胶锈菌的冬孢子、G. yamadae和亚洲胶锈菌(Gymnosporangium asiaticum)的吸器进行了转录组测序以及比较转录组学分析，建立了吸器提取体系，预测了大量的效应蛋白；对不同时期被G. yamadae侵染的苹果叶片在转录水平上的响应机制以及病程发展过程中的内生菌群落动态进行了研究；完成了山田胶锈菌侵染苹果组织的细胞学观察。本项目的完成，从基因层面上初步诠释了胶锈菌特异性选择寄主的机理。