Joseph Rageema, Odendaal Jessica L, Ingle Robert A, Roden Laura C
Department of Molecular and Cell Biology, University of Cape Town, Rondebosch 7700, South Africa.
Department of Pathology, Division of Medical Virology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa.
Philos Trans R Soc Lond B Biol Sci. 2025 Jan 23;380(1918):20230338. doi: 10.1098/rstb.2023.0338.
Plants are exposed to pathogens at specific, yet predictable times of the day-night cycle. In Arabidopsis, the circadian clock influences temporal differences in susceptibility to the necrotrophic pathogen . The jasmonic acid (JA) pathway regulates immune responses against . The paralogous basic helix-loop-helix transcription factors MYC2, MYC3 and MYC4 are primary regulators of the JA pathway, but their role in regulating temporal variation in immunity is untested. This study aimed to investigate the roles of the MYC transcription factors in the temporal defence response to . We inoculated leaves from wild-type, single-, double- and triple-knockout mutants, and lines overexpressing , or , with at two times of day in constant light, and compared lesion sizes. The presence of MYC2, MYC3 or MYC4 alone was sufficient to maintain temporal variation in susceptibility, but this was abolished in the triple-knockout mutant. Constitutive expression of , or abolished time-of-day differences in susceptibility. The data suggest that MYC2, MYC3 and MYC4 function redundantly in regulating temporal defence responses against and are a point of convergence between the JA pathway and the circadian clock in Arabidopsis.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.
植物在昼夜周期的特定但可预测的时间会接触到病原体。在拟南芥中，生物钟会影响对坏死性病原菌易感性的时间差异。茉莉酸（JA）途径调节针对……的免疫反应。同源的碱性螺旋-环-螺旋转录因子MYC2、MYC3和MYC4是JA途径的主要调节因子，但它们在调节免疫时间变化中的作用尚未得到验证。本研究旨在探究MYC转录因子在对……的时间防御反应中的作用。我们在持续光照下于一天中的两个时间点，用……接种野生型、单敲除、双敲除和三敲除突变体以及过表达……、……或……的株系的叶片，并比较病斑大小。单独存在MYC2、MYC3或MYC4足以维持易感性的时间差异，但在三敲除突变体中这种差异消失了。……、……或……的组成型表达消除了易感性的日时间差异。数据表明，MYC2、MYC3和MYC4在调节针对……的时间防御反应中发挥冗余功能，并且是拟南芥中JA途径和生物钟之间的一个交汇点。本文是西奥·墨菲会议议题“感染与免疫中的昼夜节律”的一部分。
