Comparative Analysis of the Stage- and Species-Specificity of Rust Secretomes.

专性生物营养真菌的特点是寄主和寄生虫长期共存。极有可能是蛋白质，即所谓的效应物，参与了建立和维持这种复杂的相互作用。专性生物营养的一个标志是形成特殊分化的菌丝，即吸器，渗透到宿主细胞中。这些吸器是将效应器转移到宿主和寄生虫之间的界面甚至进入宿主细胞本身的理想场所。分析了蚕豆尿霉菌的吸器分泌组，并将其与体外培养的感染结构的分泌组进行了比较，这些结构代表了寄生阶段之前的发育阶段。我们发现有62个基因编码吸体分泌的蛋白质，42个基因编码体外培养的感染结构分泌的蛋白质。其中四个基因在两个文库中都存在。这些结果表明，锈菌的蛋白质分泌具有很强的阶段特异性。在39个序列中发现了相似性，其中28个序列与仅在其他锈病中发现的蛋白质相似。这被认为是这些蛋白在毒力/致病性和宿主特异性中所起作用的证据。选定的蛋白质在免疫细胞学上定位，并开始寻找相互作用的伙伴。其中一个候选效应蛋白Uf- HSP25p可能定位于植物细胞核内。这两种实验性方法都将得到进一步的研究。在项目的第二阶段我们打算分析Phakopsora的吸器secretomes pachyrhizi和Uromyces appendiculatus利用酵母信号序列建立了与美国fabae陷阱。这将为比较不同的分泌组和鉴定对毒力/致病性至关重要的分泌蛋白创造机会。

Obligate biotrophic fungi are characterized by a prolonged co-existence of host and parasite. It is highly likely that proteins, so called effectors, are involved in establishing and maintaining this intricate interaction. A hallmark of obligate biotrophs is the formation of specially differentiated hyphae, so called haustoria, penetrating into the host cell. These haustoria are the ideal place for a transfer of effectors into the interface between host and parasite or even into the host cell itself.The haustorial secretome of Uromyces fabae was analyzed and compared to the secretome of in vitro grown infection structures representing developmental stages prior to the parasitic stage. We found 62 genes encoding proteins secreted from haustoria and 42 genes encoding proteins secreted from in vitro grown infection structures. Four of these genes were present in both libraries. These results indicate a strong stage-specificity of protein secretion in rusts. Similarities were found for 39 of the sequences, 28 of which showed similarity to proteins identified among other rusts only. This was taken as evidence for roles of these proteins in virulence/pathogenicity and host specificity unique to the Uredinales. Selected proteins were localized immunocytologically and searches for interaction partners have been initiated. One candidate effector protein, Uf- HSP25p, could be localized within the plant cell nucleus. Both experimental approaches will be further pursued. During the second phase of the project we intend to analyze the haustorial secretomes of Phakopsora pachyrhizi and Uromyces appendiculatus by using the yeast signal sequence trap established with U. fabae. This will create opportunities to compare the different secretomes and identify secreted proteins essential for virulence/pathogenicity.