MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.
Cell and Molecular Biology Program, Michigan State University, East Lansing, MI, 48824, USA.
New Phytol. 2023 Sep;239(6):2277-2291. doi: 10.1111/nph.19114. Epub 2023 Jul 4.
Jasmonate (JA) re-programs metabolism to confer resistance to diverse environmental threats. Jasmonate stimulates the degradation of JASMONATE ZIM-DOMAIN (JAZ) proteins that repress the activity of MYC transcription factors. In Arabidopsis thaliana, MYC and JAZ are encoded by 4 and 13 genes, respectively. The extent to which expansion of the MYC and JAZ families has contributed to functional diversification of JA responses is not well understood. Here, we investigated the role of MYC and JAZ paralogs in controlling the production of defense compounds derived from aromatic amino acids (AAAs). Analysis of loss-of-function and dominant myc mutations identified MYC3 and MYC4 as the major regulators of JA-induced tryptophan metabolism. We developed a JAZ family-based, forward genetics approach to screen randomized jaz polymutants for allelic combinations that enhance tryptophan biosynthetic capacity. We found that mutants defective in all members (JAZ1/2/5/6) of JAZ group I over-accumulate AAA-derived defense compounds, constitutively express marker genes for the JA-ethylene branch of immunity and are more resistant to necrotrophic pathogens but not insect herbivores. In defining JAZ and MYC paralogs that regulate the production of amino-acid-derived defense compounds, our results provide insight into the specificity of JA signaling in immunity.
茉莉酸（JA）重新编程代谢以赋予其对多种环境威胁的抗性。茉莉酸刺激 JAZ 蛋白的降解，从而抑制 MYC 转录因子的活性。在拟南芥中，MYC 和 JAZ 分别由 4 个和 13 个基因编码。MYC 和 JAZ 家族的扩张在多大程度上促进了 JA 反应的功能多样化尚不清楚。在这里，我们研究了 MYC 和 JAZ 基因家族在控制芳香族氨基酸（AAAs）衍生防御化合物的产生中的作用。功能丧失和显性 myc 突变体的分析确定 MYC3 和 MYC4 是 JA 诱导色氨酸代谢的主要调控因子。我们开发了一种基于 JAZ 家族的正向遗传学方法，筛选随机 jaz 多突变体的等位基因组合，以增强色氨酸生物合成能力。我们发现 JAZ 组 I 中所有成员（JAZ1/2/5/6）缺失的突变体过度积累 AAA 衍生的防御化合物，组成性表达 JA-乙烯免疫分支的标记基因，并且对坏死性病原体更具抗性，但对昆虫草食动物没有抗性。在定义调节氨基酸衍生防御化合物产生的 JAZ 和 MYC 基因家族，我们的结果提供了 JA 信号在免疫中的特异性的见解。
