Class V chitin synthase determines pathogenesis in the vascular wilt fungus Fusarium oxysporum and mediates resistance to plant defence compounds
Class V chitin synthase determines pathogenesis in the vascular wilt fungus Fusarium oxysporum and mediates resistance to plant defence compounds
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DOI：
10.1046/j.1365-2958.2003.03299.x
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发表时间：
2003-01-01
影响因子：
3.6
通讯作者：
Roncero, MIG
中科院分区：
文献类型：
--
作者：
Madrid, MP;Di Pietro, A;Roncero, MIG
几丁质是一种n -乙酰氨基葡萄糖的β -1,4连接多糖，是真菌细胞壁的主要结构成分。真菌有多种几丁质合成酶，可催化n -乙酰氨基葡萄糖的聚合。在这里，我们证明了V类几丁质合成酶在血管枯萎病病原菌尖孢镰刀菌感染宿主时的需求。chsV基因是在致病性突变体的插入突变筛选中鉴定出来的。ChsV具有假定的肌球蛋白马达和V类几丁质合成酶特征的几丁质合成酶结构域。尖孢镰刀菌的chsV插入突变体和基因替代突变体表现出细胞壁结构改变的菌丝肿胀等形态异常，可以通过渗透稳定剂部分恢复。突变体不能感染和定植番茄植株，也不能侵入番茄果实组织。它们也对植物抗微生物防御化合物过敏，如番茄植物预期中的α -番茄碱或H2O2。将功能性chsV拷贝重新引入突变体后，恢复了野生型菌株的生长表型。这些数据表明，尖孢镰刀菌的发病需要一种特定的V类几丁质合成酶，很可能是为了保护自己免受植物防御机制的侵害。
Chitin, a beta-1,4-linked polysaccharide of N-acetylglucosamine, is a major structural component of fungal cell walls. Fungi have multiple classes of chitin synthases that catalyse N-acetylglucosamine polymerization. Here, we demonstrate the requirement for a class V chitin synthase during host infection by the vascular wilt pathogen Fusarium oxysporum. The chsV gene was identified in an insertional mutagenesis screen for pathogenicity mutants. ChsV has a putative myosin motor and a chitin synthase domain characteristic of class V chitin synthases. The chsV insertional mutant and a gene replacement mutant of F oxysporum display morphological abnormalities such as hyphal swellings that are indicative of alterations in cell wall structure and can be partially restored by osmotic stabilizer. The mutants are unable to infect and colonize tomato plants or to grow invasively on tomato fruit tissue. They are also hypersensitive to plant antimicrobial defence compounds such as the tomato phytoanticipin alpha-tomatine or H2O2. Reintroduction of a functional chsV copy into the mutant restored the growth phenotype of the wild-type strain. These data suggest that F oxysporum requires a specific class V chitin synthase for pathogenesis, most probably to protect itself against plant defence mechanisms.