Pathogenic specialization in phytopathogenic fungi producing host-specific toxins

产生宿主特异性毒素的植物病原真菌的病原特化

• 批准号: 10460019
• 负责人: TSUGE Takashi
• 金额: $ 3.33万
• 依托单位: NAGOYA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10460019/
• 关键词: plant pathogenic fungus; Alternaria alternata; host-specific toxin; pathogenicity gene; pathogenic specialization; Alternaria alternata

Host-specific toxins are critical determinants of host-specific pathogenicity or virulence in several plant pathogenic fungi. Seven variants of Alternaria alternata produce host-specific toxins and cause severe diseases on different plants. These host-specific forms have been designated as pathotypes of A.alternata. To understand the molecular basis of pathogenic specialization in A.alternata, this research project has focused on cloning the genes required for toxin biosynthesis of the pathogens. We have studied mainly three pathotypes, Japanese pear, strawberry and tangerine, which produce AK-, AF- and ACT-toxins, respectively. These toxins have a common structural moiety, 9,10-epoxy-8-hydroxy-9-methyl-decatrienoic acid. Summary of results obtained in this research is as follows.(1) We isolated the gene cluster required for AK-toxin biosynthesis of the Japanese pear pathotype and found 11 putative open reading frames (ORFs) within an about 80-kb region. Structural analysis also found … More several transposon-like sequences within the region. Functional analysis of the ORFs identified eight genes (AKT genes) involved in AK-toxin biosynthesis.(2) We observed distribution of the AKT gene homologues in seven pathotypes and nonpathogenic stains of A.alternata by DNA gel blot analysis and found homologues of six genes in the strawberry and tangerine pathotypes.(3) We constructed cosmid genomic libraries of the strawberry and tangerine pathotypes and isolated clones containing the AKT homologues.(4) We isolated five genes (AFT genes) homologous to AKT genes and newly found three ORFs. One of the ORFs was identified as a gene specific for AF-toxin biosynthesis. We also found that the genes are located on a dispensable 1.1-Mb chromosome.(5) We isolated three genes (ACT genes) homologous to AKT genes and newly found three ORFs. We produced ACT-toxin-deficient mutants by transformation-mediated targeting of an ACT gene (ACTR). Toxin production of the mutant could be restored by introduction of the homologous gene (AKTR) of the Japanese pear pathotype, showing the functional identity of ACTR and AKTR. Less

寄主特异性毒素是植物病原真菌寄主特异性致病性或毒力的重要决定因素。Alternaria alternata的七种变种产生宿主特异性毒素，并在不同植物上引起严重疾病。这些宿主特异性形式已被指定为A. alternata的致病型。为了解互隔孢霉致病特化的分子基础，本研究计划致力于克隆病原菌毒素生物合成所需的基因。我们主要研究了三种致病型，日本梨，草莓和草莓，分别产生AK-，AF-和ACT-毒素，。这些毒素具有共同的结构部分，9，10-环氧-8-羟基-9-甲基-癸三烯酸。本研究取得的结果总结如下。(1)我们分离了日本梨致病型AK毒素生物合成所需的基因簇，并在约80 kb的区域内发现了11个推定的开放阅读框架（ORF）。结构分析还发现， ...更多信息 区域内的几个转座子样序列。对ORF的功能分析鉴定了参与AK毒素生物合成的八个基因（AKT基因）。(2)通过DNA凝胶印迹分析，观察了AKT基因同源基因在互隔孢霉7个致病型和非致病菌株中的分布，并在草莓和草莓致病型中发现了6个AKT基因同源基因。(3)我们构建了粘粒基因组文库的草莓和pathotypes和分离的克隆含有AKT同源物。(4)我们分离了5个与AKT基因同源的基因（AFT基因），并新发现了3个开放阅读框。其中一个ORF被鉴定为AF毒素生物合成的特异性基因。我们还发现这些基因位于一条1.1Mb的染色体上。(5)我们分离了三个与AKT基因同源的基因（ACT基因），并新发现了三个开放阅读框。我们通过转化介导的ACT基因（ACTR）的靶向作用产生ACT毒素缺陷突变体。通过导入日本梨致病型的同源基因（AKTR），突变体的毒素产生可以恢复，显示ACTR和AKTR的功能相同。少

项目成果

Kawamura, C.: "Targeted disruption of a melanin biosynthesis gene affects conidial development and UV torelance in the Japanese pear pathotype of Alternaria alternata"Mol.Plant-Microbe Interact.. 12 (1). 59-63 (1999)

Kawamura, C.：“黑色素生物合成基因的靶向破坏会影响日本梨链格孢病型的分生孢子发育和紫外线耐受性”Mol.Plant-Microbe Interact.. 12 (1)。

Okuda,M.: "Tfol:an Ac-like transposon of the plant pathogenic fungus Fusarium oxysporum" Molecular & General Genetics. 258(6). 599-607 (1998)

Okuda，M.：“Tfol：植物病原真菌尖孢镰刀菌的 Ac 样转座子”分子

Kaneko,I.: "REAL: an LTR retrotransposon of the plant pathogenic fungus Alternaria alternata"Molecular and General Genetics. (印刷中). (2000)

Kaneko, I.：“REAL：植物病原真菌 Alternaria alternata 的 LTR 逆转录转座子”《分子与普通遗传学》（出版中）。

Tsuge, T.: "Diversity and Use of Agricultural Microorganisms"K.Kato et al., eds., Research Council Secretariat of MAFF and National Institute of Agrobiological Resources. 283 (1999)

Tsuge, T.：“农业微生物的多样性和利用”K.Kato 等人编辑，MAFF 研究委员会秘书处和国家农业生物资源研究所。

Tsuge,T.: "Diversity and Use of Agricultural Microorganisms" K.Kato et al.,eds.,Research Council Secretariat of MAFF and National Institute of Agrobiological Resources(印刷中), (1999)

Tsuge, T.：“农业微生物的多样性和利用”K. Kato 等人编辑，MAFF 和国家农业生物资源研究所研究委员会秘书处（出版中），（1999 年）