The role of ANAC072 in the regulation of chlorophyll degradation during age- and dark-induced leaf senescence
The role of ANAC072 in the regulation of chlorophyll degradation during age- and dark-induced leaf senescence
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DOI：
10.1007/s00299-016-1991-1
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发表时间：
2016-08-01
影响因子：
6.2
通讯作者：
Kuai, Benke
中科院分区：
文献类型：
--
作者：
Li, Shou;Gao, Jiong;Kuai, Benke
ANAC072通过激活NYE1的转录，正向调节衰老和暗诱导的叶片衰老。叶片衰老是植物发育过程中不可或缺的一部分，它依赖于年龄，并受到内部和环境信号的严格调控。虽然在过去的几十年里，已经发现了一些与衰老相关的突变体和衰老相关基因(SAGs)，但对叶片衰老的一般调控网络仍远未阐明。在这里，我们报告了ANAC072，一个通过生物信息学分析确定的SAG，在调节自然和黑暗诱导的叶片衰老过程中的叶绿素降解中的作用。在拟南芥中，ANAC072的表达随着叶片衰老的推进而增加。ANAC072的敲除突变体anac072-1在正常或暗诱导条件下叶片脱色显著延迟，并检测到较高的叶绿素水平。相反，ANAC072转录显著上调的过表达突变体anac072-2表现出叶片提前变黄的表型。与野生型Col-0植株相比，功能丧失突变体anac072-1的衰老叶片光系统II的光合作用效率(F(V)/F(M)比)的下降和质膜离子渗漏速率的增加都表现出延缓的趋势，而高表达突变体anac072-2的变化则相反。我们的数据表明，ANAC072在自然和黑暗诱导的叶片衰老过程中起着积极的作用。此外，叶绿素降解的关键调控基因NYE1的转录水平依赖于ANAC072的功能。结合这些分析，结合凝胶迁移率改变分析和染色质免疫沉淀，我们证明ANAC072在体外和体内都直接与NYE1启动子结合，因此ANAC072可能通过直接上调NYE1的表达来促进叶绿素的降解。
ANAC072 positively regulates both age- and dark-induced leaf senescence through activating the transcription of NYE1.Leaf senescence is integral to plant development, which is age-dependent and strictly regulated by internal and environmental signals. Although a number of senescence-related mutants and senescence-associated genes (SAGs) have been identified and characterized in the past decades, the general regulatory network of leaf senescence is still far from being elucidated. Here, we report the role of ANAC072, an SAG identified through bioinformatics analysis, in the regulation of chlorophyll degradation during natural and dark-induced leaf senescence. The expression of ANAC072 was increased with advancing leaf senescence in Arabidopsis. Leaf degreening was significantly delayed under normal or dark-induced conditions in anac072-1, a knockout mutant of ANAC072, with a higher chlorophyll level detected. In contrast, an overexpression mutant, anac072-2, with ANAC072 transcription markedly upregulated, showed an early leaf-yellowing phenotype. Consistently, senescent leaves of the loss-of-function mutant anac072-1 exhibited delays in the decrease of photosynthesis efficiency of photosystem II (F (v)/F (m) ratio) and the increase of plasma membrane ion leakage rate as compared with corresponding leaves of wild-type Col-0 plants, whereas the overexpression mutant anac072-2 showed opposite changes. Our data suggest that ANAC072 plays a positive role during natural and dark-induced leaf senescence. In addition, the transcript level of NYE1, a key regulatory gene in chlorophyll degradation, relied on the function of ANAC072. Combining these analyses with electrophoretic mobility shift assay and chromatin immunoprecipitation, we demonstrated that ANAC072 directly bound to the NYE1 promoter in vitro and in vivo, so ANAC072 may promote chlorophyll degradation by directly upregulating the expression of NYE1.