Degradation of the benzoxazolinone class of phytoalexins is important for virulence of Fusarium pseudograminearum towards wheat
Degradation of the benzoxazolinone class of phytoalexins is important for virulence of Fusarium pseudograminearum towards wheat
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DOI：
10.1111/mpp.12250
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发表时间：
2015-12-01
影响因子：
4.9
通讯作者：
Gardiner, Donald M.
中科院分区：
文献类型：
--
作者：
Kettle, Andrew J.;Batley, Jacqueline;Gardiner, Donald M.
小麦、玉米、黑麦和禾本科的某些其他农业重要物种在害虫和病原体攻击时产生苯并恶唑啉酮类植物抗毒素。苯并恶唑啉酮类可以抑制病原体的生长。然而，某些真菌可以主动解毒这些化合物。尽管如此，苯并恶唑啉酮类解毒能力与病原体毒力之间的明确联系尚未得到证实。在此，通过对几种镰刀菌属物种的比较基因组分析，我们鉴定了 FDB2 基因周围的一个保守基因组区域，该区域编码 N-丙二酰转移酶，已知该酶参与玉米病原体轮枝镰刀菌中苯并恶唑啉酮的降解。表达分析表明，在重要的小麦病原体假禾谷镰刀菌中，九个基因簇对外源苯并恶唑啉酮有反应。对独立的假禾谷镰刀菌FDB2敲除分析以及与来自禾谷镰刀菌和轮枝镰刀菌的FDB2同源物的敲除互补的分析证实，该基因编码的N-丙二酰转移酶对于苯并恶唑啉酮类的解毒至关重要，并且在赤霉病接种测定中，Fdb2对小麦的毒力有定量贡献。这与之前在 F.verticillioides 中的观察结果形成鲜明对比，其中没有观察到 FDB2 突变对病原体对玉米的毒力产生影响。总的来说，我们的结果表明，苯并恶唑啉酮的解毒是感染小麦的假禾谷镰刀菌克服宿主化学防御的一种策略。
Wheat, maize, rye and certain other agriculturally important species in the Poaceae family produce the benzoxazolinone class of phytoalexins on pest and pathogen attack. Benzoxazolinones can inhibit the growth of pathogens. However, certain fungi can actively detoxify these compounds. Despite this, a clear link between the ability to detoxify benzoxazolinones and pathogen virulence has not been shown. Here, through comparative genome analysis of several Fusarium species, we have identified a conserved genomic region around the FDB2 gene encoding an N-malonyltransferase enzyme known to be involved in benzoxazolinone degradation in the maize pathogen Fusarium verticillioides. Expression analyses demonstrated that a cluster of nine genes was responsive to exogenous benzoxazolinone in the important wheat pathogen Fusarium pseudograminearum. The analysis of independent F.pseudograminearumFDB2 knockouts and complementation of the knockout with FDB2 homologues from F.graminearum and F.verticillioides confirmed that the N-malonyltransferase enzyme encoded by this gene is central to the detoxification of benzoxazolinones, and that Fdb2 contributes quantitatively to virulence towards wheat in head blight inoculation assays. This contrasts with previous observations in F.verticillioides, where no effect of FDB2 mutations on pathogen virulence towards maize was observed. Overall, our results demonstrate that the detoxification of benzoxazolinones is a strategy adopted by wheat-infecting F.pseudograminearum to overcome host-derived chemical defences.