Functional genomics of Pseudozyma flocculosa, a biocontrol agent of powdery mildews

植物病原体生物防治的实际应用前提是对这些现象背后的遗传、分子和生态事件有透彻的了解。这一挑战一直是申请人实验室在过去25年中开展的研究活动的焦点。在上一期中，我们在阐明控制白粉病真菌天然拮抗剂假酶（Pseudozyma cullosa）生物防治特性的复杂因素方面取得了一些重大进展。特别重要的是，我们报道了以下几个方面：1)发现了参与絮凝素生物合成的基因和一个基因簇，并与系统发育相关的植物病原体模式真菌黑穗病菌建立了意想不到的密切联系；2)絮凝草与麦冬草糖脂结构特异性酶活性的关系；3)首次报道了絮状假单胞菌（P. floculosa）的完整测序和基因组注释；4)与相关菌种Ustilaginales、U. maydis、Sporisorium reilianum和U. hordei基因组进行比较分析，以确定真菌特定生活方式的遗传因素。后一项成就被认为是一项重大突破，因为它为了解使系统发育相关的真菌采取相反生活方式的微妙因素提供了新的机会。在这一应用的背景下，并与我们最近的进展直接相关，目标是：1)使用P. floculosa - blumeria graminis-大麦系统对三营养相互作用bca -真菌病原体-植物进行首次全转录组分析；2)特别强调了在絮凝草基因组中发现的独特因子，以确定赋予絮凝草对白粉病真菌的生物防治活性的决定因素；3)通过推导分析白粉病真菌对絮状假单胞菌的抑制作用，确定白粉病真菌的功能毒力因子；4)了解植物在维持bca -植物病原体互作中的作用；5)通过对絮凝假单胞菌（P. floculosa）的反向遗传和（或）麦氏假单胞菌（U. maydis）的互补进行生物防治决定因素（基因）的功能分析。实现这些目标将产生关于以下方面的新颖和独特的信息：调节P.絮凝菌生物防治活性的遗传决定因素和调节白粉病真菌对植物致病性的遗传决定因素，以及这些决定因素的表达（或抑制）如何影响真菌的生态。这些结果将对植物病理学领域产生深远的影响，因为我们的模型将为分离和调节两种系统发育相关的真菌作为生物防治剂或植物病原体的内在遗传因素提供独特的数据

Practical application of biological control of plant pathogens presupposes a thorough understanding of the genetic, molecular and ecological events underlying such phenomena. This challenge has been the focal point of the research activities carried out in the applicant's laboratory over the last 25 years. In the previous installment, we have made some major strides toward elucidating the complex factors governing the biocontrol properties of Pseudozyma flocculosa, a natural antagonist of powdery mildew fungi. Of particular significance, we reported the following: 1) the discovery of genes and a gene cluster involved in flocculosin biosynthesis and establishment of an unsuspected close link with the phylogenetically related plant pathogen model fungus Ustilago maydis; 2) the association of specific enzymatic activities distinguishing the glycolipid structures produced by P. flocculosa and U. maydis; 3) the complete sequencing and genomic annotation of P. flocculosa, the first such report for a biocontrol agent; and 4) the comparative analysis of P. flocculosa genome with that of related Ustilaginales, U. maydis, Sporisorium reilianum and U. hordei, aimed at identifying the genetic factors that confer specific lifestyles in fungi. This latter achievement is perceived as a major breakthrough since it opens new opportunities to understand the subtle factors that make phylogenetically related fungi adopt opposite lifestyles. In the context of this application and in direct link with our recent progress, the objectives are: 1) to carry out the first full transcriptomic analysis of a tritrophic interaction BCA-fungal pathogen-plant using the system P. flocculosa-Blumeria graminis-barley; 2) with a specific emphasis on the unique factors discovered in the genome of P. flocculosa, to identify the determinant(s) that confer P. flocculosa, its biocontrol activity on powdery mildew fungi; 3) to identify the functional virulence factors of powdery mildew fungi by deductive analysis of their repression under P. flocculosa attack; 4) to understand the plant's role in sustaining the BCA-plant pathogen interaction; and 5) to conduct functional analyses of biocontrol determinants (genes) through reverse genetics in P. flocculosa and/or complementation in U. maydis. Fulfillment of these objectives will generate novel and distinctive information with regards to: the genetic determinants that regulate the biocontrol activity of P. flocculosa and those that regulate the pathogenicity of powdery mildew fungi against plants, and how expression (or repression) of these determinants influence the ecology of fungi. These results will have far reaching impact into the field of plant pathology as our model will provide unique data into the intrinsic genetic factors that separate and modulate two phylogenetically related fungi to behave as biocontrol agent or plant pathogen.**