Data_Sheet_1_Volatile Molecules Secreted by the Wheat Pathogen Parastagonospora nodorum Are Involved in Development and Phytotoxicity.pdf

Septoria nodorum blotch is a major disease of wheat caused by the fungus Parastagonospora nodorum. Recent studies have demonstrated that secondary metabolites, including polyketides and non-ribosomal peptides, produced by the pathogen play important roles in disease and development. However, there is currently no knowledge on the composition or biological activity of the volatile organic compounds (VOCs) secreted by P. nodorum. To address this, we undertook a series of growth and phytotoxicity assays and demonstrated that P. nodorum VOCs inhibited bacterial growth, were phytotoxic and suppressed self-growth. Mass spectrometry analysis revealed that 3-methyl-1-butanol, 2-methyl-1-butanol, 2-methyl-1-propanol, and 2-phenylethanol were dominant in the VOC mixture and phenotypic assays using these short chain alcohols confirmed that they were phytotoxic. Further analysis of the VOCs also identified the presence of multiple sesquiterpenes of which four were identified via mass spectrometry and nuclear magnetic resonance as β-elemene, α-cyperone, eudesma-4,11-diene and acora-4,9-diene. Subsequent reverse genetics studies were able to link these molecules to corresponding sesquiterpene synthases in the P. nodorum genome. However, despite extensive testing, these molecules were not involved in either of the growth inhibition or phytotoxicity phenotypes previously observed. Plant assays using mutants of the pathogen lacking the synthetic genes revealed that the identified sesquiterpenes were not required for disease formation on wheat leaves. Collectively, these data have significantly extended our knowledge of the VOCs in fungi and provided the basis for further dissecting the roles of sesquiterpenes in plant disease.

小麦上的Septoria nodorum斑点病是由真菌Parastagonospora nodorum引起的重大病害。近期的研究表明，病原体产生的次生代谢产物，包括聚酮和核糖体非肽类，在病害的发生与发展中扮演着关键角色。然而，目前尚无关于P. nodorum分泌的挥发性有机化合物（VOCs）的组成或生物活性的认识。为此，我们开展了一系列的生长与植物毒性试验，并证实P. nodorum的VOCs能够抑制细菌生长，具有植物毒性并抑制自身生长。质谱分析揭示了3-甲基-1-丁醇、2-甲基-1-丁醇、2-甲基-1-丙醇和2-苯乙醇在VOC混合物中占主导地位，使用这些短链醇进行的表型试验证实了它们的植物毒性。进一步对VOCs的分析还鉴定出多种倍半萜，其中四种通过质谱和核磁共振被鉴定为β-芴烯、α-细辛醚、乌斯玛-4,11-二烯和鹅掌楸-4,9-二烯。随后的反向遗传学研究将这些分子与P. nodorum基因组中的相应倍半萜合酶联系起来。然而，尽管进行了广泛的测试，这些分子并未涉及先前观察到的生长抑制或植物毒性表型。使用缺乏合成基因的病原体突变体进行的植物试验表明，这些鉴定的倍半萜对于小麦叶片上的病害形成并非必需。综上所述，这些数据显著拓展了我们对真菌中VOCs的认识，并为进一步剖析倍半萜在植物病害中的作用奠定了基础。