HRB2 and BBX21 interaction modulates Arabidopsis ABI5 locus and stomatal aperture
HRB2 and BBX21 interaction modulates Arabidopsis ABI5 locus and stomatal aperture
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HRB2 和 BBX21 相互作用调节拟南芥 ABI5 基因座和气孔孔径
DOI：
10.1111/pce.13336
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发表时间：
2018-08-01
影响因子：
7.3
通讯作者：
Ni, Min
中科院分区：
文献类型：
--
作者：
Kang, Xiaojun;Xu, Gang;Ni, Min
蓝光会在早晨触发气孔的打开，从而通过蒸腾作用吸收二氧化碳和损失水分。在白天，植物可能经历周期性的干旱和积累脱落酸（ABA）。ABA通过磷脂酸拮抗蓝光信号，减少气孔开度。本研究揭示了两种光信号蛋白相互作用抑制ABA信号调控气孔孔径的分子机制。在色域/解旋酶/DNA结合家族中，对红蓝2 （hrb2）敏感的突变体具有缺陷的atp依赖性染色质重塑因子PKL。HRB2增强光诱导的B-box转录因子基因BBX21的表达。BBX21结合ABI5启动子中的T/G盒子，招募HRB2来调节ABI5位点的染色质结构。HRB2或BBX21突变导致水分流失减少和ABA过敏。这两种突变体中ABA信号基因ABI5的表达增强可以很好地解释对ABA的超敏反应。事实上，在单色光条件下，在没有ABA或存在ABA的情况下，ABI5的过表达显著降低了气孔孔径。总的来说，我们提出了一个调控回路，其中两个光信号蛋白抑制ABA信号，以维持植物经历周期性干旱时的气体交换。
Blue light triggers the opening of stomata in the morning to allow CO2 uptake and water loss through transpiration. During the day, plants may experience periodic drought and accumulate abscisic acid (ABA). ABA antagonizes blue light signalling through phosphatidic acid and reduces stomatal aperture. This study reveals a molecular mechanism by which two light signalling proteins interact to repress ABA signalling in the control of stomatal aperture. A hypersensitive to red and blue 2 (hrb2) mutant has a defective ATP-dependent chromatin-remodelling factor, PKL, in the chromodomain/helicase/DNA binding family. HRB2 enhances the light-induced expression of a B-box transcription factor gene, BBX21. BBX21 binds a T/G box in the ABI5 promoter and recruits HRB2 to modulate the chromatin structure at the ABI5 locus. Mutation in either HRB2 or BBX21 led to reduced water loss and ABA hypersensitivity. This hypersensitivity to ABA was well explained by the enhanced expression of the ABA signalling gene ABI5 in both mutants. Indeed, stomatal aperture was significantly reduced by ABI5 overexpression in the absence or presence of ABA under monochromatic light conditions. Overall, we present a regulatory loop in which two light signalling proteins repress ABA signalling to sustain gas exchange when plants experience periodic drought.