Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany.
Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 113-8657 Tokyo, Japan.
Plant Cell. 2019 Jan;31(1):84-105. doi: 10.1105/tpc.18.00766. Epub 2019 Jan 3.
Abscisic acid (ABA) is a plant hormone that regulates a diverse range of cellular and molecular processes during development and in response to osmotic stress. In Arabidopsis (), three Suc nonfermenting-1-related protein kinase2s (SnRK2s), SRK2D, SRK2E, and SRK2I, are key positive regulators involved in ABA signaling whose substrates have been well studied. Besides reduced drought-stress tolerance, the mutant shows abnormal growth phenotypes, such as an increased number of leaves, under nonstress conditions. However, it remains unclear whether, and if so how, SnRK2-mediated ABA signaling regulates growth and development. Here, we show that the primary metabolite profile of grown under nonstress conditions was considerably different from that of wild-type plants. The metabolic changes observed in the were similar to those in an ABA-biosynthesis mutant, , and both mutants showed a higher leaf emergence rate than wild type. Consistent with the increased amounts of citrate, isotope-labeling experiments revealed that respiration through the tricarboxylic acid cycle was enhanced in These results, together with transcriptome data, indicate that the SnRK2s involved in ABA signaling modulate metabolism and leaf growth under nonstress conditions by fine-tuning flux through the tricarboxylic acid cycle.
脱落酸（ABA）是一种植物激素，它在发育过程中以及对渗透胁迫的反应中调节多种细胞和分子过程。在拟南芥（）中，三种蔗糖非发酵-1 相关蛋白激酶 2（SnRK2），SRK2D、SRK2E 和 SRK2I，是参与 ABA 信号转导的关键正调节因子，其底物已得到很好的研究。除了抗旱胁迫耐受性降低外，突变体在非胁迫条件下还表现出异常的生长表型，例如叶片数量增加。然而，目前尚不清楚 SnRK2 介导的 ABA 信号转导是否以及如何调节生长和发育。在这里，我们表明，在非胁迫条件下生长的突变体的主要代谢物谱与野生型植物有很大的不同。在中观察到的代谢变化与 ABA 生物合成突变体相似，两者突变体的叶片出现率均高于野生型。与柠檬酸含量增加一致，同位素标记实验表明，三羧酸循环的呼吸作用增强。这些结果与转录组数据一起表明，参与 ABA 信号转导的 SnRK2 通过微调三羧酸循环的通量来调节非胁迫条件下的代谢和叶片生长。
