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Mechanisms of host-recognition by plant pathogens mediated by signaling factors for pathogenicity

致病性信号因子介导的植物病原体宿主识别机制

基本信息

批准号：
13660052
负责人：
KODAMA Motoichiro
金额：
$ 2.11万
依托单位：
Tottori University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13660052/
关键词：
plant pathogen host-specific toxin AAL-toxin AM-toxin pathogenicity gene horizontal gene transfer ポリケチド CD染色体

项目摘要

Fungal pathogenicity are predicted to release signaling molecules essential for path ogenicity during the process of infection. Although essential components for fungal pathogenesis are still unknown in many plant pathogenic fungi, certain fungal pathogens, especially the genera Alternaria and Cochliobolus, are known to produce host-specific toxins (HSTs) as compatibility agents. There are now ten or more Alternaria pathogena, mainly A. alternata pathotypes, known to produce HSTs, and the structures of most of the toxins have been elucidated. HSTs from A.alternata pathotypes have been classified into three groups based on their chemical structures, I.e.polyketides, cyclic peptides and decatrienoic acid esters. Recently a polyketied synthetase gene and a cyclic-peptide synthetase gene, involved in AAL-toxin and AM-toxin biosynthesis, respectively, have been cloned and characterized. In both cases, targeted gene disruption lead to elimination of toxin production and loss of pathogenisity indicating that HST biosynthetic genes are fungal pathogenicity determinants. These HST biosynthetic genes also reside on conditionally dispensable chromosomes found only in the pathogenic and HST-producing strains of A.alrernata and homologues of the genes were not detected in nonpathogenic strains of A.alrernata. This suggests that these genes may have been acquired by horizontal gene transfer and provides a possible mechanism whereby new pathotypes could arise in nature.

预测真菌致病性在感染过程中释放通路致病性所必需的信号分子。虽然在许多植物病原真菌中，真菌发病机制的基本成分尚不清楚，但已知某些真菌病原体，特别是Alternaria属和Cochliobolus属，可以产生宿主特异性毒素（HSTs）作为相容性剂。目前已知有十种或更多的交替孢杆菌（主要是交替孢杆菌）产生HSTs，并且大多数毒素的结构已经被阐明。根据其化学结构，将其分为聚酮类、环肽类和十三烯酸酯类。近年来，分别克隆和鉴定了一个参与aal毒素和am毒素生物合成的聚酮合成酶基因和一个环肽合成酶基因。在这两种情况下，靶向基因破坏导致毒素产生的消除和致病性的丧失，这表明HST生物合成基因是真菌致病性的决定因素。这些HST生物合成基因也存在于条件必需的染色体上，这些基因只存在于病原菌和产生HST的菌株中，而在非致病菌株中未检测到同源基因。这表明这些基因可能是通过水平基因转移获得的，并提供了一种可能的机制，即新的病理类型可能在自然界中出现。