Pisatin demethylation by fungal pathogens and nonpathogens of pea: association with pisatin tolerance and virulence
Pisatin demethylation by fungal pathogens and nonpathogens of pea: association with pisatin tolerance and virulence
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DOI：
10.1006/pmpp.1999.0237
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发表时间：
1999-12-01
影响因子：
2.7
通讯作者：
Vanetten, HD
中科院分区：
文献类型：
--
作者：
Delserone, LM;McCluskey, K;Vanetten, HD
先前的研究表明，寄主植物抗毒素的解毒是一些真正的真菌的耐受机制，而不是真菌样的卵菌，并且可能参与决定病原体的毒力。在本研究中，对代表17种豌豆病原菌和非病原菌的50株真菌分离株进行了豌豆植物抗菌素pisatin去甲基化、对pisatin的耐受性和对豌豆的毒力之间的关系进行了研究。所有分离的coloratum和P. irregulum都不能代谢并且对pisatin敏感：这与之前的观察一致，卵菌科的成员通常缺乏代谢能力并且对宿主的系统降解素敏感。在真正的真菌测试中，去甲基化pisatin的能力是普遍的，无论特定的分离物是否对豌豆致病。然而，当将鱼素去甲基化的速率与毒力进行比较时，除了一株中等到高毒力的分离株外，所有分离株都能迅速去甲基化鱼素。此外，去甲基化速度越快的菌株通常对pisatin的耐受性越强。这些结果表明，在大多数豌豆病原体中可能存在一种专门的酶系统来快速解毒鱼素。在以往的研究中，在豌豆病原菌血球菌（Nectria haematococca）交配群体VI中发现了一种特异性的鱼素去甲基化酶P450，并从该真菌中克隆出了编码该酶的基因（PDA基因）。当使用这些基因特异性的DNA来探测其他去甲基化pisatin的真菌的基因组DNA时，只检测到与豌豆病原体Fusarium oxysporum f. sp. pisi的显著杂交。如果其他豌豆病原体具有特异性的细胞色素P450解毒系统，那么编码这些基因的基因与嗜血嗜血杆菌的PDA基因相似。酶显然共享有限的核苷酸(C) 1999学术出版社。
Previous studies have indicated that detoxification of their hosts' phytoalexins is a tolerance mechanism for some true fungi, but not the fungus-like Oomycota, and may be involved in determining the virulence of a pathogen. Ill the present study, the associations between demethylation of the pea phytoalexin pisatin, tolerance to pisatin, and virulence on pea were examined for 50 fungal isolates which represent 17 species of pathogens and nonpathogens of pea. All isolates of Pythium coloratum and P. irregulare failed to metabolize and were sensitive to pisatin: consistent with previous observations that members of the Oomycota generally lack the ability to metabolize and are sensitive to their hosts' phyloalexins. Among true fungi tested, the ability to demethylate pisatin was common, regardless of whether the particular isolate was pathogenic on pea or not. However, when the rate of pisatin demethylation was compared to virulence, all bur one of the moderate to highly virulent isolates rapidly demethylated pisatin. In addition, the more rapidly demethylating isolates were generally more tolerant of pisatin. These results suggest that a specialized enzyme system for quickly detoxifying pisatin might be present in most pea pathogens. In previous studies a specific cytochrome P450 enzyme for demethylating pisatin was identified in the pea pathogen Nectria haematococca mating population VI and genes (PDA genes) encoding that enzyme have been cloned from this fungus. When DNA specific for these genes was used to probe genomic DNA from other fungi that demethylate pisatin, significant hybridization was detected with only one fungus, the pea pathogen Fusarium oxysporum f. sp. pisi. If the other pea pathogens possess a specific cytochrome P450 system for detoxification of pisatin, the genes encoding these similarity with N. haematococca PDA genes. enzymes apparently share limited nucleotide (C) 1999 Academic Press.