Circadian control of abscisic acid biosynthesis and signalling pathways revealed by genome-wide analysis of LHY binding targets
Circadian control of abscisic acid biosynthesis and signalling pathways revealed by genome-wide analysis of LHY binding targets
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DOI：
10.1111/nph.15415
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发表时间：
2018-11-01
期刊：
影响因子：
9.4
通讯作者：
Carre, Isabelle A.
中科院分区：
文献类型：
--
作者：
Adams, Sally;Grundy, Jack;Carre, Isabelle A.
LHY转录因子是拟南芥生物钟振荡机制的一部分。本文报道了LHY结合靶基因的全基因组分析，揭示了LHY在控制脱落酸（阿坝）生物合成和下游反应中的作用，LHY直接抑制9-顺式-环氧类胡萝卜素双加氧酶的表达，该酶催化阿坝生物合成的限速步骤。这表明在野生型植物阿坝积累的昼夜节律控制的机制。与这一假设相一致，阿坝积累有节奏的野生型植物，在晚上达到峰值。LHY过表达的植物在干旱胁迫下阿坝水平降低，而功能丧失的突变体表现出阿坝积累的节奏改变。LHY还结合了阿坝信号通路的多个组件的启动子，这表明它也可能起到调节激素下游反应的作用。LHY促进ABA响应基因的表达，提高植物对干旱和渗透胁迫的耐受性，但减轻阿坝对种子萌发和植物生长的抑制作用。本研究揭示了生物钟和阿坝途径之间的复杂相互作用，这可能是在干旱和渗透胁迫条件下的植物表现作出重要贡献。
The LATE ELONGATED HYPOCOTYL (LHY) transcription factor functions as part of the oscillatory mechanism of the Arabidopsis circadian clock. This paper reports the genome-wide analysis of its binding targets and reveals a role in the control of abscisic acid (ABA) biosynthesis and downstream responses.LHY directly repressed expression of 9-cis-epoxycarotenoid dioxygenase enzymes, which catalyse the rate-limiting step of ABA biosynthesis. This suggested a mechanism for the circadian control of ABA accumulation in wild-type plants. Consistent with this hypothesis, ABA accumulated rhythmically in wild-type plants, peaking in the evening. LHY-overexpressing plants had reduced levels of ABA under drought stress, whereas loss-of-function mutants exhibited an altered rhythm of ABA accumulation.LHY also bound the promoter of multiple components of ABA signalling pathways, suggesting that it may also act to regulate responses downstream of the hormone. LHY promoted expression of ABA-responsive genes responsible for increased tolerance to drought and osmotic stress but alleviated the inhibitory effect of ABA on seed germination and plant growth.This study reveals a complex interaction between the circadian clock and ABA pathways, which is likely to make an important contribution to plant performance under drought and osmotic stress conditions.