The NAC transcription factor ANAC046 is a positive regulator of chlorophyll degradation and senescence in Arabidopsis leaves.
The NAC transcription factor ANAC046 is a positive regulator of chlorophyll degradation and senescence in Arabidopsis leaves.
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DOI：
10.1038/srep23609
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发表时间：
2016-03-29
影响因子：
4.6
通讯作者：
Ohmiya A
中科院分区：
文献类型：
--
作者：
Oda-Yamamizo C;Mitsuda N;Sakamoto S;Ogawa D;Ohme-Takagi M;Ohmiya A
叶绿素（Chl）降解发生在叶片衰老、胚去角质、芽断裂和果实成熟过程中。Chl的分解代谢途径已被深入研究，几乎所有涉及的酶都已被鉴定和表征；然而，这一途径的分子调控机制在很大程度上是未知的。在本研究中，我们利用转录因子cDNA文库进行酵母单杂交筛选，寻找控制Chl分解代谢基因表达的因子。我们发现ANAC046是直接结合NON-YELLOW COLORING1、STAY-GREEN1 （SGR1）、SGR2和PHEOPHORBIDE a OXYGENASE启动子区域的共同调节因子。与野生型相比，过表达ANAC046的转基因植株表现出较早的衰老表型和较低的Chl含量，而功能缺失突变体表现出较晚的衰老表型和较高的Chl含量。对ANAC046转基因植株的芯片分析表明，ANAC046不仅对Chl分解代谢基因有正向调控作用，而且对衰老相关基因也有正向调控作用。我们认为ANAC046是拟南芥叶片衰老的正调控因子，通过调控Chl分解代谢基因和衰老相关基因的表达来发挥作用。
Chlorophyll (Chl) degradation occurs during leaf senescence, embryo degreening, bud breaking, and fruit ripening. The Chl catabolic pathway has been intensively studied and nearly all the enzymes involved are identified and characterized; however, the molecular regulatory mechanisms of this pathway are largely unknown. In this study, we performed yeast one-hybrid screening using a transcription factor cDNA library to search for factors controlling the expression of Chl catabolic genes. We identified ANAC046 as a common regulator that directly binds to the promoter regions of NON-YELLOW COLORING1, STAY-GREEN1 (SGR1), SGR2, and PHEOPHORBIDE a OXYGENASE. Transgenic plants overexpressing ANAC046 exhibited an early-senescence phenotype and a lower Chl content in comparison with the wild-type plants, whereas loss-of-function mutants exhibited a delayed-senescence phenotype and a higher Chl content. Microarray analysis of ANAC046 transgenic plants showed that not only Chl catabolic genes but also senescence-associated genes were positively regulated by ANAC046. We conclude that ANAC046 is a positive regulator of Arabidopsis leaf senescence and exerts its effect by controlling the expression of Chl catabolic genes and senescence-associated genes.