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

宿主特异性毒素是几种植物病原真菌宿主特异性致病性或毒力的关键决定因素。链格孢 (Alternaria alternata) 的七种变种会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。为了了解链格孢病原菌特化的分子基础，该研究项目的重点是克隆病原体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、草莓和橘子，它们分别产生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-十碳三烯酸。本研究的结果总结如下。(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80kb的区域内发现了11个假定的开放阅读框(ORF)。结构分析还发现该区域内有几个类似转座子的序列。对ORF进行功能分析，鉴定出8个参与AK毒素生物合成的基因（AKT基因）。(2)通过DNA凝胶印迹分析观察了AKT基因同源物在链格孢7个致病型和非致病性菌株中的分布，并在草莓和柑橘致病型中发现了6个基因的同源物。(3)构建了链格孢的粘粒基因组文库。 (4)分离得到5个与AKT基因同源的基因(AFT基因),新发现3个ORF。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可有可无的1.1-Mb染色体上。(5)我们分离出3个与AKT基因同源的基因(ACT基因)并新发现了3个ORF。我们通过转化介导的 ACT 基因 (ACTR) 靶向来生产 ACT 毒素缺陷突变体。通过引入日本梨致病型的同源基因（AKTR）可以恢复突变体的毒素产生，显示出 ACTR 和 AKTR 的功能同一性。较少的

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）