Functional characterization of conserved putative effector proteins in the Sebacinales

Piriformospora indica和密切相关的担子菌Sebacina vermifera （MAFF 305830）属于生态分布广泛的皮脂菌门，是在早期进化中从真菌门分支出来的一个目，具有广泛的菌根类型。P. indica和S. vermifera都是根内生菌，具有促进生长和增强对病原体抗性等广泛的有益作用。印度假单胞菌是从印度塔尔沙漠的木本灌木毛豆（Prosopis juliflora）和紫茎（Zizyphus nummularia）的根际中分离出来的，但环境分子分析已经揭示了在世界各地的各种植物中普遍存在的密切相关序列，包括兰花和拟南芥。S. vermifera是从澳大利亚陆生兰花（Cyrtostylis reniformis）中分离出来的，被认为是一种兰花菌根真菌（ORM），因为它能够刺激这些寄主的种子萌发和幼苗发育。与JGI合作，对线虫35mb基因组进行了200倍的测序。这种真菌的遗传转化已经建立，并使用比较基因组学和转录组学（微阵列和RNA-seq）的生物信息学工具来鉴定植物反应基因。比较表明，一个核心的假定的效应蛋白是保守的相关的类油脂素分离物，但似乎没有更遥远的共生体和腐养真菌。为了深入了解类油脂素真菌如何在不同寄主的代谢活性根细胞中建立自己，以及植物如何重新编程以提高性能，我们建议使用综合方法，依赖于反向遗传学，转录组学，细胞生物学，生物化学和比较基因组学的结合，以找到以下问题的答案：A)在P. indica和S. vermifera之间是否存在功能保守的效应物？B)油脂素效应蛋白如何介导宿主调节和相互作用？C)生态上不同的根内生菌是否有共同的定殖机制和信号传递？

Piriformospora indica and the closely related basidiomycete Sebacina vermifera (MAFF 305830) belong to the ecologically widely distributed Sebacinales, an order that branched off the Agaricomycotina early in the evolution and harbors a broad spectrum of mycorrhizal types. P. indica and S. vermifera are both root endophytes that display wide-host spectrum beneficial effects, such as growth promotion and increased resistance to pathogens. P. indica was isolated from the rhizosphere of the woody shrubs Prosopis juliflora and Zizyphus nummularia at the Indian Thar desert but environmental molecular analyses have unravelled a ubiquitous distribution of closely related sequences within various plants worldwide including orchids and Arabidopsis. S. vermifera was isolated from a terrestrial Australian orchid (Cyrtostylis reniformis) and is considered an orchid mycorrhizal fungus (ORM) because of its capability to stimulate seed germination and seedling development in these hosts. In cooperation with the JGI the 35 Mb genome of S. vermifera was sequenced with 200 fold coverage. The genetic transformation of this mycobiont has been established and bioinformatics tools for comparative genomics and transcriptomics (microarrays and RNA-seq) were used to identify the in planta-responsive genes. The comparison has revealed that a core of putative effector-proteins is conserved in the related sebacinoid isolates but seems to be absent in more distantly related symbionts and saprotrophic fungi. With respect to insights into how sebacinoid fungi establishes themselves in metabolically active root cells of different hosts and how the plants are reprogrammed for enhanced performance, we propose to use integrated approaches that rely on the combination of reverse genetics, transcriptomics, cell biology, biochemistry, and comparative genomics to find answers to the following questions:A) Are there functionally conserved effectors between P. indica and S. vermifera?B) How do the sebacinoid effector proteins mediate host accommodation and mutualism? C) Do ecologically different root endophytes share common colonization mechanisms and signalling?