Molecular Horticulture Pub Date : 2023-10-30 , DOI: 10.1186/s43897-023-00072-1
Gaopeng Wang 1 , Xingwang Liu 2 , Su-Sheng Gan 3
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We previously reported that ABA inhibits stomatal closure through AtNAP-SAG113 PP2C regulatory module during leaf senescence. The mechanism by which this module exerts its function is unknown. Here we report the identification and functional analysis of SAG114, a direct target of the regulatory module. SAG114 encodes SnRK3.25. Both bimolecular fluorescence complementation (BiFC) and yeast two-hybrid assays show that SAG113 PP2C physically interacts with SAG114 SnRK3.25. Biochemically the SAG113 PP2C dephosphorylates SAG114 in vitro and in planta. RT-PCR and GUS reporter analyses show that SAG114 is specifically expressed in senescing leaves in Arabidopsis. Functionally, the SAG114 knockout mutant plants have a significantly bigger stomatal aperture and a much faster water loss rate in senescing leaves than those of wild type, and display a precocious senescence phenotype. The premature senescence phenotype of sag114 is epistatic to sag113 (that exhibits a remarkable delay in leaf senescence) because the sag113 sag114 double mutant plants show an early leaf senescence phenotype, similar to that of sag114. These results not only demonstrate that the ABA-AtNAP-SAG113 PP2C regulatory module controls leaf longevity by dephosphorylating SAG114 kinase, but also reveal the involvement of the SnRK3 family gene in stomatal movement and water loss during leaf senescence.
Graphical Abstract
中文翻译：
ABA-AtNAP-SAG113 PP2C 模块通过去磷酸化拟南芥中的 SAG114 SnRK3.25 来调节叶片衰老
我们之前报道过 ABA 在叶片衰老过程中通过 AtNAP-SAG113 PP2C 调节模块抑制气孔关闭。该模块发挥其功能的机制尚不清楚。在这里，我们报告了调节模块的直接目标SAG114的识别和功能分析。 SAG114编码 SnRK3.25。双分子荧光互补 (BiFC) 和酵母双杂交测定均表明 SAG113 PP2C 与 SAG114 SnRK3.25 发生物理相互作用。在体外和植物体内， SAG113 PP2C 的生物化学作用使 SAG114 去磷酸化。 RT-PCR 和 GUS 报告基因分析表明，SAG114在拟南芥衰老叶片中特异性表达。在功能上，SAG114敲除突变体植物比野生型植物具有明显更大的气孔孔径和更快的衰老叶片失水率，并表现出早熟表型。sag114的过早衰老表型与sag113相比是上位性的（表现出叶片衰老的显着延迟），因为sag113 sag114双突变体植物表现出与sag114相似的早期叶片衰老表型。这些结果不仅证明ABA-AtNAP-SAG113 PP2C调控模块通过去磷酸化SAG114激酶来控制叶片寿命，而且揭示了SnRK3家族基因参与叶片衰老过程中的气孔运动和水分流失。
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