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. Over half of the ABI4-modulated genes were independent of the phosphorylation state of ABI4; these are enriched for stress responses. 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.

中文翻译：

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转录因子ABSCISIC ACID INSENSITIVE 4的Serine114磷酸化对于活性至关重要

转录因子ABA-INSENSITIVE（ABI）4在调节植物生长中具有多种作用，包括抑制发芽和响应ABA和高盐分的动员储备，抑制高糖响应的幼苗生长，抑制侧根生长以及抑制光照。诱导的基因表达。ABI4活性受到多个水平的调控，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在多个残基处磷酸化，但我们发现S114是MPK3的首选位点。为了检查S114磷酸化的可能生物学作用，我们用编码ABI4的野生型（114S），磷酸化无效（S114A）或磷酸化（S114E）形式的ABI4pro :: ABI4构建体转化了abi4-1突变植物。S114的磷酸化对于ABA的反应是必需的，葡萄糖，盐胁迫和侧根发育，其中可以通过表达ABI4（114S）或ABI4（S114E）而非ABI4（S114A）来补充abi4表型。比较用编码ABI4的S114的不同磷酸化形式的构建体转化的ABA4-1突变植物的ABA处理的根中的根转录组，发现有85％的ABI4调控基因可以通过表达ABI4（114S）来恢复其表达模式被ABI4下调。超过一半的ABI4调节基因独立于ABI4的磷酸化状态；这些丰富了压力反应。S114的磷酸化是调控35％的受抑制基因所必需的，但只有17％的诱导基因被调控。其阻抑需要S114磷酸化的基因主要参与胚胎和幼苗的发育，