The Arabidopsis RING Finger E3 Ligase RHA2b Acts Additively with RHA2a in Regulating Abscisic Acid Signaling and Drought Response
The Arabidopsis RING Finger E3 Ligase RHA2b Acts Additively with RHA2a in Regulating Abscisic Acid Signaling and Drought Response
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拟南芥环指 E3 连接酶 RHA2b 与 RHA2a 共同调节脱落酸信号传导和干旱反应
DOI：
10.1104/pp.111.176214
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发表时间：
2011-06-01
期刊：
影响因子：
7.4
通讯作者：
Li, Chuanyou
中科院分区：
文献类型：
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作者：
Li, Hongmei;Jiang, Hongling;Li, Chuanyou
我们之前已经证明，拟南芥（Arabidopsis thaliana） RING-H2 E3连接酶RHA2a在种子萌发和萌发后生长过程中积极调节脱落酸（ABA）信号。在这里，我们报道了RHA2a最接近的同源物RHA2b也是一个活跃的E3连接酶，在ABA信号传导中起重要作用。我们发现，ABA诱导了RHA2b的表达，并且RHA2b的过表达导致了ABA相关的表型，如种子萌发和幼苗生长中ABA超敏，气孔关闭增强，水分流失减少，因此耐旱性增强。相反，rha2b-1突变体表现为aba不敏感表型，耐旱性降低。我们提供的证据表明，rha2a - RHA2b -1双突变体在种子萌发、幼苗生长和气孔关闭过程中普遍增强了RHA2b -1对ABA的不敏感性，这表明RHA2b和rha2a在调节ABA反应中起冗余作用。遗传分析支持，与RHA2a一样，RHA2b在ABA信号传导中的作用位于蛋白磷酸酶2C ABA- insensitive2 （ABI2）的下游，并与ABI转录因子ABI3/4/5平行。我们推测，RHA2b和RHA2a可能在调控ABA反应中具有冗余但可区分的功能。
We have previously shown that the Arabidopsis (Arabidopsis thaliana) RING-H2 E3 ligase RHA2a positively regulates abscisic acid (ABA) signaling during seed germination and postgerminative growth. Here, we report that RHA2b, the closest homolog of RHA2a, is also an active E3 ligase and plays an important role in ABA signaling. We show that RHA2b expression is induced by ABA and that overexpression of RHA2b leads to ABA-associated phenotypes such as ABA hypersensitivity in seed germination and seedling growth, enhanced stomatal closure, reduced water loss, and, therefore, increased drought tolerance. On the contrary, the rha2b-1 mutant shows ABA-insensitive phenotypes and reduced drought tolerance. We provide evidence showing that a rha2a rha2b-1 double mutant generally enhances ABA insensitivity of rha2b-1 in seed germination, seedling growth, and stomatal closure, suggesting that RHA2b and RHA2a act redundantly in regulating ABA responses. Genetic analyses support that, like RHA2a, the RHA2b action in ABA signaling is downstream of a protein phosphatase 2C, ABA-INSENSITIVE2 (ABI2), and in parallel with that of the ABI transcription factors ABI3/4/5. We speculate that RHA2b and RHA2a may have redundant yet distinguishable functions in the regulation of ABA responses.