Lignin, a major component of the secondary cell wall, is important for plant growth and development. Moreover, lignin plays a pivotal role in plant innate immunity. Lignin is readily deposited upon pathogen infection and functions as a physical barrier that limits the spread of pathogens. In this study, we show that an Arabidopsis MYB transcription factor MYB15 is required for the activation of lignin biosynthesis genes such as PAL, C4H, 4CL, HCT, C3′H, COMT, and CAD, and consequently lignin formation during effector-triggered immune responses. Upon challenge with the avirulent bacterial pathogen Pst DC3000 (AvrRpm1), lignin deposition and disease resistance were reduced in myb15 mutant plants. Furthermore, whereas invading pathogens, together with hypersensitive cell death, were restricted to the infection site in wild-type leaves, they spread beyond the infected area in myb15 mutants. The exogenous supply of the lignin monomer coniferyl alcohol restored lignin production and rescued immune defects in myb15 plants. These results demonstrate that regulation at the transcriptional level is key to pathogen-induced lignification and that MYB15 plays a central role in this process.

木质素是次生细胞壁的主要成分，对植物的生长发育至关重要。此外，木质素在植物固有免疫中起关键作用。木质素易于在病原体感染时沉积，并起限制病原体扩散的物理屏障的作用。在这项研究中，我们表明拟南芥MYB转录因子MYB15是激活木质素生物合成基因如朋友， C4H， 4CL， HCT， C3′H， COMT和 计算机辅助设计，并因此在效应子触发的免疫反应过程中形成木质素。挑战无毒细菌病原体后太平洋标准时间 DC3000（AvrRpm1），降低了木质素的沉积和抗病能力 myb15突变植物。此外，尽管入侵的病原体以及超敏细胞死亡被限制在野生型叶片的感染部位，但它们却扩散到了感染区域之外。myb15突变体。木质素单体松柏油醇的外源供应恢复了木质素的产生，并拯救了小鼠的免疫缺陷。myb15植物。这些结果表明，在转录水平上的调控是病原体诱导的木质化的关键，而MYB15在此过程中起着核心作用。