Zhao Yulei, Agrawal Nisha, Ghareeb Hassan, Habib Mohammad Tanbir, Dickmeis Sascha, Schwachtje Jens, Iven Tim E, Kopka Joachim, Feussner Ivo, Schirawski Jan
Department of Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, Julia-Lermontowa-Weg 3, 37077 Göttingen, Germany.
Department of Microbial Genetics, Institute of Applied Microbiology, RWTH Aachen University, Worringer Weg 1, 52074 Aachen, Germany.
J Fungi (Basel). 2022 May 11;8(5):498. doi: 10.3390/jof8050498.
Genome comparison between the maize pathogens and revealed a large diversity region (19-1) containing nearly 30 effector gene candidates, whose deletion severely hampers virulence of both fungi. Dissection of the gene cluster resulted in the identification of one major contributor to virulence, (; ). Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) experiments revealed high expression of during biotrophic growth of . Using the yeast secretion trap assay, we confirmed the existence of a functional signal peptide allowing protein secretion via the conventional secretory pathway. We identified the cytoplasmic maize chorismate mutase ZmCM2 by yeast two-hybrid screening as a possible interaction partner of Vag2. Interaction of the two proteins in planta was confirmed by bimolecular fluorescence complementation. qRT-PCR experiments revealed -dependent downregulation of salicylic acid (SA)-induced genes, which correlated with higher SA levels in plant tissues colonized by Δ deletion strains relative to wildtype strains. Metabolite analysis suggested rewiring of pathogen-induced SA biosynthesis by preferential conversion of the SA precursor chorismate into the aromatic amino acid precursor prephenate by ZmCM2 in the presence of Vag2. Possibly, the binding of Vag2 to ZmCM2 inhibits the back reaction of the ZmCM2-catalyzed interconversion of chorismate and prephenate, thus contributing to fungal virulence by lowering the plant SA-induced defenses.
玉米病原体之间的基因组比较显示出一个包含近30个效应子基因候选物的大的多样性区域（19-1），其缺失严重阻碍了两种真菌的毒力。对该基因簇的剖析导致鉴定出一种对毒力有主要贡献的基因（；）。定量逆转录聚合酶链反应（qRT-PCR）实验显示在生物营养生长期间该基因高表达。使用酵母分泌陷阱试验，我们证实了存在一个功能性信号肽，允许蛋白质通过传统分泌途径分泌。我们通过酵母双杂交筛选鉴定细胞质玉米分支酸变位酶ZmCM2作为Vag2的可能相互作用伙伴。通过双分子荧光互补证实了两种蛋白质在植物中的相互作用。qRT-PCR实验显示水杨酸（SA）诱导基因的 - 依赖性下调，这与Δ缺失菌株定殖的植物组织中相对于野生型菌株更高的SA水平相关。代谢物分析表明，在存在Vag2的情况下，ZmCM2通过将SA前体分支酸优先转化为芳香族氨基酸前体预苯酸，重新连接病原体诱导的SA生物合成。可能，Vag2与ZmCM2的结合抑制了ZmCM2催化的分支酸和预苯酸相互转化的逆反应，从而通过降低植物SA诱导的防御来促进真菌毒力。
