Barda Omer, Levy Maggie
Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
Front Plant Sci. 2022 Apr 26;13:845140. doi: 10.3389/fpls.2022.845140. eCollection 2022.
IQ Domain 1 (IQD1) is a novel calmodulin-binding protein, which was found to be a positive regulator of glucosinolate (GS) accumulation and plant defense responses against insects. We demonstrate here that the IQD1 overexpressing line ( ) was also more resistant also to the necrotrophic fungus , whereas an IQD1 knockout line () was much more sensitive. Furthermore, we showed that IQD1 is up-regulated by jasmonic acid (JA) and downregulated by salicylic acid (SA). A comparison of whole transcriptome expression between and wild type plants revealed a substantial downregulation of genes involved in plant defense and hormone regulation. Further examination revealed a marked reduction of SA and increases in the levels of ethylene, JA and abscisic acid response genes in the line. Moreover, quantification of SA, JA, and abscisic acids in and lines relative to the wild type, showed a significant reduction in endogenous JA levels in the knockout line, simultaneously with increased SA levels. Relations between and mutants defective in plant-hormone response indicated that IQD1 cannot rescue the absence of NPR1 or impaired SA accumulation in the NahG line. IQD1 cannot rescue or mutations connected to the ethylene pathway involved in both defense responses against and in regulating GS accumulation. Furthermore, IQD1cannot rescue the , or mutations, all involved in the defense response against and it depends on JAR1 to control indole glucosinolate accumulation. We also found that in the , which infected the mutant, the most abundant upregulated group of proteins is involved in the degradation of complex carbohydrates, as correlated with the sensitivity of this mutant. In summary, our results suggest that IQD1 is an important defensive protein against that is integrated into several important pathways, such as those involved in plant defense and hormone responses.
IQ结构域1（IQD1）是一种新型钙调蛋白结合蛋白，被发现是芥子油苷（GS）积累和植物对昆虫防御反应的正调控因子。我们在此证明，IQD1过表达系（ ）对坏死营养型真菌 也更具抗性，而IQD1敲除系（ ）则更为敏感。此外，我们表明IQD1受茉莉酸（JA）上调，受水杨酸（SA）下调。 与野生型植物之间的全转录组表达比较显示，参与植物防御和激素调节的基因大幅下调。进一步检查发现， 系中SA显著减少，乙烯、JA和脱落酸反应基因水平增加。此外，相对于野生型，对 系和 系中的SA、JA和脱落酸进行定量分析，结果显示敲除系中内源性JA水平显著降低，同时SA水平升高。 与植物激素反应缺陷型突变体之间的关系表明，IQD1无法挽救NahG系中NPR1缺失或SA积累受损的情况。IQD1无法挽救与乙烯途径相关的 或 突变，这些突变既参与对 的防御反应，也参与调节GS积累。此外，IQD1无法挽救 、 或 突变，所有这些突变都参与对 的防御反应，并且它依赖JAR1来控制吲哚芥子油苷的积累。我们还发现，在感染 突变体的 中，最丰富的上调蛋白组参与复合碳水化合物的降解，这与该突变体的敏感性相关。总之，我们的结果表明，IQD1是一种重要的针对 的防御蛋白，它整合到几个重要途径中，例如参与植物防御和激素反应的途径。
