Turella Simone, He Cheng, Zhao Lin, Banerjee Sanchari, Plouhinec Lauriane, Assiah Yao Roseline, Nørgaard Kejlstrup Mette Christine, Grisel Sacha, So Yunjeong, Annic Bastien, Fanuel Mathieu, Haddad Momeni Majid, Bissaro Bastien, Meier Sebastian, Morth Jens Preben, Dong Suomeng, Berrin Jean-Guy, Abou Hachem Maher
Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark.
State Key Laboratory of Agricultural and Forestry Biosecurity, College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
Nat Commun. 2025 Apr 11;16(1):3467. doi: 10.1038/s41467-025-58668-8.
Phytophthora phytopathogens from Oomycota cause devastating crop losses and threaten food security. However, Phytophthora secreted proteins that interact with plant-hosts remain underexplored. Here, auxiliary activity family 7 (AA7) enzymes from Ascomycota and Oomycota phytopathogens were shown to oxidise pectin-derived galacturonic acid and/or oligogalacturonides (OGs). Unique mono-cysteinyl-FAD oxidases with positively-charged active sites, suited to oxidise OGs, were discovered in Phytophthora sojae. The P. sojae OG oxidase genes, prevalent in this genus, were co-transcribed with pectin-degradation counterparts during early infection of soybean. Single OG oxidase knockouts significantly decreased P. sojae biomass in planta, potentially linking OG oxidases to virulence. We propose that oxidation by AA7 enzymes impairs the elicitor activity of OGs, potentially contributing to stealth Oomycota infection. Oxidation of OGs unravels a previously unknown microbial mechanism that contributes to evade plant immune-response against pathogens. Our findings highlight a unique oxidase architecture and hitherto unexplored targets for bioprotection from major plant pathogens.
卵菌纲的疫霉属植物病原体可导致农作物严重减产，并威胁粮食安全。然而，疫霉属与植物宿主相互作用的分泌蛋白仍未得到充分研究。在这里，来自子囊菌纲和卵菌纲植物病原体的辅助活性家族7（AA7）酶被证明可氧化果胶衍生的半乳糖醛酸和/或寡聚半乳糖醛酸（OGs）。在大豆疫霉中发现了具有带正电荷活性位点的独特单半胱氨酸-FAD氧化酶，适合氧化OGs。大豆疫霉OG氧化酶基因在该属中普遍存在，在大豆早期感染期间与果胶降解对应基因共同转录。单个OG氧化酶基因敲除显著降低了大豆疫霉在植物体内的生物量，这可能将OG氧化酶与毒力联系起来。我们认为，AA7酶的氧化作用会损害OGs的激发子活性，这可能有助于卵菌纲的隐秘感染。OGs的氧化揭示了一种以前未知的微生物机制，有助于逃避植物对病原体的免疫反应。我们的研究结果突出了一种独特的氧化酶结构以及迄今未被探索的针对主要植物病原体进行生物保护的靶点。
