The wheat PKABA1-interacting factor TaABF1 mediates both abscisic acid-suppressed and abscisic acid-induced gene expression in bombarded aleurone cells
The wheat PKABA1-interacting factor TaABF1 mediates both abscisic acid-suppressed and abscisic acid-induced gene expression in bombarded aleurone cells
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DOI：
10.1007/s11103-008-9354-0
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发表时间：
2008-09-01
影响因子：
5.1
通讯作者：
Shen, Jeff Q.
中科院分区：
文献类型：
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作者：
Johnson, Russell R.;Shin, Margaret;Shen, Jeff Q.
为了研究小麦（Triticum aestivum）中脱落酸（阿坝）和赤霉素（GA）信号转导的相互作用，我们重点研究了转录因子TaABF1。TaABF 1（阿坝反应元件结合因子家族的成员）与PKABA 1发生物理相互作用，PKABA 1是谷物中脱落酸抑制赤霉素诱导的基因表达的信号成分。TaABF1在吸胀谷粒糊粉层细胞中的组成型表达完全消除了Amy32b启动子的GA诱导表达。除了对Amy32b的作用外，TaABF1还强烈刺激ABA诱导型HVA1和HVA22启动子的表达。TaABF1的过表达完全取代外源阿坝在这两个启动子的诱导。引入指导TaABF1的RNA抑制（RNAi）的构建体并不能阻止ABA介导的或PKABA 1介导的Amy32b表达抑制。类似地，RNAi构建体不阻止ABA诱导HVA1。这些结果表明，另一种蛋白质可能与TaABF1在谷物吸胀过程中起冗余作用。虽然TaABF1 mRNA在吸胀的后熟谷物下调，转录水平没有显着改变外源GA或阿坝，这表明在mRNA水平上的上调TaABF1是不需要的阿坝信号的作用。我们提出了一个模型，其中TaABF1参与阿坝信号的两个独立分支。在该模型中，TaABF1在ABA抑制GA诱导的基因表达中作用于PKABA1的下游，并参与（独立于PKABA1）ABA诱导的基因的刺激。
To investigate the crosstalk of abscisic acid (ABA) and gibberellin (GA) signaling in wheat (Triticum aestivum), we have focused on the transcription factor TaABF1. TaABF1 (a member of the ABA response element binding factor family) physically interacts with PKABA1, a signaling component in the ABA-suppression of GA-induced gene expression in cereal grains. Constitutive expression of TaABF1 in aleurone cells of imbibing grains completely eliminated GA-induced expression from the Amy32b promoter. In addition to its effect on Amy32b, TaABF1 strongly stimulated expression from the ABA-inducible HVA1 and HVA22 promoters. Overexpression of TaABF1 fully substituted for exogenous ABA in the induction of these two promoters. The introduction of a construct directing RNA inhibition (RNAi) of TaABF1 did not prevent either ABA-mediated or PKABA1-mediated suppression of Amy32b expression. Similarly, the RNAi construct did not prevent ABA-induction of HVA1. These results suggest that another protein may act redundantly with TaABF1 during cereal imbibition. Although TaABF1 mRNA was downregulated during imbibition of afterripened grains, transcript levels were not significantly altered by exogenous GA or ABA, suggesting that upregulation of TaABF1 at the mRNA level is not required for its role in ABA signaling. We propose a model in which TaABF1 is involved in two separate branches of ABA signaling. In this model, TaABF1 acts downstream of PKABA1 in ABA-suppression of GA-induced gene expression, and participates (independently of PKABA1) in the stimulation of ABA-induced genes.