An Abscisic Acid-AtNAP Transcription Factor-SAG113 Protein Phosphatase 2C Regulatory Chain for Controlling Dehydration in Senescing Arabidopsis Leaves
An Abscisic Acid-AtNAP Transcription Factor-SAG113 Protein Phosphatase 2C Regulatory Chain for Controlling Dehydration in Senescing Arabidopsis Leaves
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DOI：
10.1104/pp.111.190876
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发表时间：
2012-02-01
期刊：
影响因子：
7.4
通讯作者：
Gan, Su-Sheng
中科院分区：
文献类型：
--
作者：
Zhang, Kewei;Gan, Su-Sheng
AtNAP是一个NAC家族转录因子基因，在叶片衰老过程中起关键作用，但其潜在机制尚不清楚。衰老相关基因GENE113(SAG113)编码高尔基体定位的蛋白磷酸酶2C家族蛋白磷酸酶，介导脱落酸(ABA)调节的气孔运动和叶片衰老过程中的失水。在此，我们报道SAG113是AtNAP转录因子的直接靶基因。我们发现AtNAP和SAG113都是由叶片衰老和ABA诱导的。当AtNAP被化学诱导时，SAG113也被诱导，而当AtNAP被敲除时，ABA和衰老诱导的SAG113的表达减少。这些数据表明SAG113的表达主要依赖于AtNAP。在功能上，SAG113的过表达使atnap基因敲除后显著延迟的叶片衰老表型恢复为野生型。酵母(Saccharmyces Cerevisiae)单杂交实验和凝胶迁移率改变分析表明，AtNAP在体内和体外均能与SAG113启动子物理结合。定点突变表明，AtNAP与SAG113启动子的核心序列5‘CACGTAAGT3’相结合。这些结果表明，在叶片衰老过程中，存在一个独特的调控链--ABA-AtNAP-SAG113蛋白磷酸酶2C，它控制气孔运动和水分损失。
AtNAP is a NAC family transcription factor gene that plays a key role in leaf senescence but its underlying mechanisms are not known. SENESCENCE-ASSOCIATED GENE113 (SAG113), a gene encoding a Golgi-localized protein phosphatase 2C family protein phosphatase, mediates abscisic acid (ABA)-regulated stomatal movement and water loss specifically during leaf senescence. Here we report that SAG113 is a direct target gene of the AtNAP transcription factor. We found that both AtNAP and SAG113 were induced by leaf senescence and ABA. When AtNAP was chemically induced, SAG113 was also induced whereas when AtNAP was knocked out, the ABA- and senescence-induced expression of SAG113 was reduced. These data suggest that the expression of SAG113 is predominantly dependent on AtNAP. Functionally, overexpression of SAG113 restored the markedly delayed leaf senescence phenotype in atnap knockouts to wild type. Yeast (Saccharomyces cerevisiae) one-hybrid experiments and electrophoresis mobility shift assays showed that AtNAP could physically bind to the SAG113 promoter in vivo and in vitro, respectively. Site-directed mutagenesis revealed that AtNAP binds to a 9-bp core sequence of the SAG113 promoter, 5'CACGTAAGT3'. These results indicate that there is a unique regulatory chain, ABA-AtNAP-SAG113 protein phosphastase 2C, which controls stomatal movement and water loss during leaf senescence.