Department of Plant Pathology, Nanjing Agricultural University, 210095 Nanjing, China.
Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Proc Natl Acad Sci U S A. 2020 Nov 3;117(44):27685-27693. doi: 10.1073/pnas.2012149117. Epub 2020 Oct 20.
Hosts and pathogens are engaged in a continuous evolutionary struggle for physiological dominance. A major site of this struggle is the apoplast. In -soybean interactions, PsXEG1, a pathogen-secreted apoplastic endoglucanase, is a key focal point of this struggle, and the subject of two layers of host defense and pathogen counterdefense. Here, we show that N-glycosylation of PsXEG1 represents an additional layer of this coevolutionary struggle, protecting PsXEG1 against a host apoplastic aspartic protease, GmAP5, that specifically targets PsXEG1. This posttranslational modification also attenuated binding by the previously described host inhibitor, GmGIP1. N-glycosylation of PsXEG1 at N174 and N190 inhibited binding and degradation by GmAP5 and was essential for 's full virulence contribution, except in GmAP5-silenced soybeans. Silencing of GmAP5 reduced soybean resistance against WT but not against deletion strains of The crucial role of N-glycosylation within the three layers of defense and counterdefense centered on PsXEG1 highlight the critical importance of this conserved apoplastic effector and its posttranslational modification in -host coevolutionary conflict.
宿主和病原体为了生理优势而进行持续的进化斗争。这场斗争的一个主要场所是质外体。在大豆与病原体的相互作用中，PsXEG1 是一种由病原体分泌的质外体内切葡聚糖酶，是这场斗争的关键焦点，也是两层宿主防御和病原体反防御的主题。在这里，我们表明，PsXEG1 的 N-糖基化代表了这种共同进化斗争的另一个层面，它可以保护 PsXEG1 免受专门针对 PsXEG1 的宿主质外体天冬氨酸蛋白酶 GmAP5 的攻击。这种翻译后修饰还减弱了先前描述的宿主抑制剂 GmGIP1 的结合。PsXEG1 在 N174 和 N190 处的 N-糖基化抑制了 GmAP5 的结合和降解，对于 PsXEG1 的完全毒力贡献是必不可少的，除了在 GmAP5 沉默的大豆中。GmAP5 的沉默降低了大豆对 WT 的抗性，但对 的缺失菌株则没有。在以 PsXEG1 为中心的三层防御和反防御中，N-糖基化的关键作用突显了这种保守的质外体效应物及其翻译后修饰在 -宿主共同进化冲突中的关键重要性。
