Department of Biochemistry, Division of Biological Sciences, Indian Institute of Science (IISc), Bengaluru 560012, India.
Biomolecules. 2023 Sep 9;13(9):1368. doi: 10.3390/biom13091368.
Jasmonic acid (JA) is a plant hormone that regulates a plethora of physiological processes including immunity and development and is perceived by the F-Box protein, Coronatine-insensitive protein 1 (COI1). The discovery of inositol phosphates (InsPs) in the COI1 receptor complex highlights their role in JAperception. InsPs are phosphate-rich signaling molecules that control many aspects of plant physiology. Inositol pyrophosphates (PP-InsPs) are diphosphate containing InsP species, of which InsP and InsP are the best characterized ones. Different InsP and PP-InsP species are linked with JA-related plant immunity. However, role of PP-InsP species in regulating JA-dependent developmental processes are poorly understood. Recent identification of ITPK1 kinase, responsible for the production of 5-InsP from InsP, provides a platform to investigate the possible involvement of ITPK-derived InsP species in JA-related plant development. Here, in this study, we report that ITPK1-defective plants exhibit increased root growth inhibition to bioactive JA treatment. The plants also show increased lateral root density when treated with JA. Notably, JA treatment does not increase ITPK1 protein levels. Gene expression analyses revealed that JA-biosynthetic genes are not differentially expressed in ITPK1-deficient plants. We further demonstrate that genes encoding different JAZ repressor proteins are severely down-regulated in ITPK1-defective plants. Taken together, our study highlights the role of ITPK1 in regulating JA-dependent root architecture development through controlling the expression of different JAZ repressor proteins.
茉莉酸（JA）是一种植物激素，可调节多种生理过程，包括免疫和发育，并被 F-Box 蛋白，冠状蛋白 1（COI1）感知。在 COI1 受体复合物中发现肌醇磷酸盐（InsPs）突出了它们在 JA 感知中的作用。InsPs 是富含磷酸盐的信号分子，可控制植物生理学的许多方面。肌醇六磷酸（PP-InsPs）是含有二磷酸的 InsP 物质，其中 InsP 和 InsP 是研究最充分的两种。不同的 InsP 和 PP-InsP 物质与与 JA 相关的植物免疫有关。但是，PP-InsP 物质在调节 JA 依赖性发育过程中的作用还知之甚少。最近鉴定出 ITPK1 激酶，该激酶负责从 InsP 产生 5-InsP，为研究 ITPK 衍生的 InsP 物质在与 JA 相关的植物发育中的可能参与提供了一个平台。在这项研究中，我们报告说，ITPK1 缺陷型植物对生物活性 JA 处理的根生长抑制作用增强。JA 处理也会增加侧根密度。值得注意的是，JA 处理不会增加 ITPK1 蛋白水平。基因表达分析显示，ITPK1 缺陷型植物中 JA 生物合成基因的表达没有差异。我们进一步证明，编码不同 JAZ 抑制蛋白的基因在 ITPK1 缺陷型植物中严重下调。综上所述，我们的研究强调了 ITPK1 通过控制不同 JAZ 抑制蛋白的表达来调节 JA 依赖性根结构发育的作用。
