Lignin‐based barrier restricts pathogens to the infection site and confers resistance in plants

First author: Myoung‐Hoon Lee; Affiliations: Korea University (高丽大学): Seoul, Korea

Corresponding author: Ohkmae K Park

Pathogenic bacteria invade plant tissues and proliferate in the extracellular space. Plants have evolved the immune system to recognize and limit the growth of pathogens. Despite substantial progress in the study of plant immunity, the mechanism by which plants limit pathogen growth remains unclear. Here, we show that lignin accumulates in Arabidopsis leaves in response to incompatible interactions with bacterial pathogens in a manner dependent on Casparian strip membrane domain protein (CASP)‐like proteins (CASPLs). CASPs are known to be the organizers of the lignin‐based Casparian strip, which functions as a diffusion barrier in roots. The spread of invading avirulent pathogens is prevented by spatial restriction, which is disturbed by defects in lignin deposition. Moreover, the motility of pathogenic bacteria is negatively affected by lignin accumulation. These results suggest that the lignin‐deposited structure functions as a physical barrier similar to the Casparian strip, trapping pathogens and thereby terminating their growth.

病原菌侵入植物组织，并在细胞外的空间增殖。植物已经演化出了免疫系统来识别并限制病原菌的生长。尽管植物免疫相关的研究取得了重要的进展，但是关于植物如何限制病原菌生长的分子机制还不是很清楚。本文中，作者的研究显示拟南芥的叶片在响应于与细菌病原菌不相容互作时的木质素积累取决于类凯氏带的膜结构域蛋白CASPL。已知CASP蛋白作用于凯氏带（根的内皮层细胞在径向壁和横向壁上的木质化和栓质化带状加厚），而凯氏带则在根中充当着扩散屏障。通过空间限制能够防止入侵的无毒病原体的扩散，而这会受到木质素沉积缺陷的干扰。 此外，木质素的积累会对致病细菌的移动有负面影响。 这些结果表明，木质素沉积结构起到类似于凯氏带的物理屏障的作用，通过捕获病原体，从而终止其生长。

通讯：Ohkmae K Park (https://koreauniv.pure.elsevier.com/en/persons/ohkmae-kim)

个人简介：1995年，弗吉尼亚大学，博士。

doi: https://doi.org/10.15252/embj.2019101948

Journal: The EMBO Journal

Published date: September 26, 2019