Department of Life Sciences and The Doris and Bertie Black Center for Bioenergetics in Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410500, Israel.
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel.
Plant Sci. 2021 Apr;305:110847. doi: 10.1016/j.plantsci.2021.110847. Epub 2021 Feb 13.
The transcription factor ABA-INSENSITIVE(ABI)4 has diverse roles in regulating plant growth, including inhibiting germination and reserve mobilization in response to ABA and high salinity, inhibiting seedling growth in response to high sugars, inhibiting lateral root growth, and repressing light-induced gene expression. ABI4 activity is regulated at multiple levels, including gene expression, protein stability, and activation by phosphorylation. Although ABI4 can be phosphorylated at multiple residues by MAPKs, we found that S114 is the preferred site of MPK3. To examine the possible biological role of S114 phosphorylation, we transformed abi4-1 mutant plants with ABI4pro::ABI4 constructs encoding wild type (114S), phosphorylation-null (S114A) or phosphomimetic (S114E) forms of ABI4. Phosphorylation of S114 is necessary for the response to ABA, glucose, salt stress, and lateral root development, where the abi4 phenotype could be complemented by expressing ABI4 (114S) or ABI4 (S114E) but not ABI4 (S114A). Comparison of root transcriptomes in ABA-treated roots of abi4-1 mutant plants transformed with constructs encoding the different phosphorylation-forms of S114 of ABI4 revealed that 85 % of the ABI4-regulated genes whose expression pattern could be restored by expressing ABI4 (114S) are down-regulated by ABI4. Phosphorylation of S114 was required for regulation of 35 % of repressed genes, but only 17 % of induced genes. The genes whose repression requires the phosphorylation of S114 are mainly involved in embryo and seedling development, growth and differentiation, and regulation of gene expression.
转录因子 ABA-INSENSITIVE（ABI）4 在调节植物生长方面具有多种作用，包括抑制萌发和对 ABA 和高盐的储备动员，抑制幼苗生长对高糖的反应，抑制侧根生长，并抑制光诱导基因表达。ABI4 的活性受到多个水平的调节，包括基因表达、蛋白质稳定性和磷酸化激活。尽管 ABI4 可以被 MAPKs 在多个残基上磷酸化，但我们发现 S114 是 MPK3 的首选位点。为了研究 S114 磷酸化的可能生物学作用，我们将 ABI4pro::ABI4 构建体转化为 abi4-1 突变体植物，该构建体编码野生型（114S）、磷酸化缺失（S114A）或磷酸化模拟（S114E）形式的 ABI4。S114 磷酸化是对 ABA、葡萄糖、盐胁迫和侧根发育做出反应所必需的，abi4 表型可以通过表达 ABI4（114S）或 ABI4（S114E）但不是 ABI4（S114A）来互补。比较 abi4-1 突变体植物 ABA 处理根中不同 S114 磷酸化形式的 ABI4 编码构建体转化的根转录组，发现 85%的 ABI4 调节基因的表达模式可以通过表达 ABI4（114S）来恢复，这些基因的表达水平被 ABI4 下调。S114 磷酸化是调节 35%受抑制基因所必需的，但只调节 17%的诱导基因。需要 S114 磷酸化来调节抑制的基因主要涉及胚胎和幼苗发育、生长和分化以及基因表达的调控。
