Department of Agriculture Technology, Faculty of Agriculture, University Putra Malaysia, UPM, 43400 Selangor, Malaysia.
Mol Biol Rep. 2012 Sep;39(9):8907-18. doi: 10.1007/s11033-012-1758-x. Epub 2012 Jun 22.
Abscisic acid (ABA) is an important phytohormone involved in the abiotic stress resistance in plants. The ABA-responsive element (ABRE) binding factors play significant roles in the plant development and response to abiotic stresses, but none so far have been isolated and characterized from the oil palm. Two ABA-responsive cDNA clones, named EABF and EABF1, were isolated from the oil palm fruits using yeast one-hybrid system. The EABF had a conserved AP2/EREBP DNA-binding domain (DNA-BD) and a potential nuclear localization sequence (NLS). No previously known DNA-BD was identified from the EABF1 sequence. The EABF and EABF1 proteins were classified as DREB/CBF and bZIP family members based on the multiple sequence alignment and phylogenetic analysis. Both proteins showed ABRE-binding and transcriptional activation properties in yeast. Furthermore, both proteins were able to trans-activate the down-stream expression of the LacZ reporter gene in yeast. An electrophoretic mobility shift assay revealed that in addition to the ABRE sequence, both proteins could bind to the DRE sequence as well. Transcriptional analysis revealed that the expression of EABF was induced in response to the ABA in the oil palm fruits and leaves, but not in roots, while the EABF1 was constitutively induced in all tissues. The expressions of both genes were strongly induced in fruits in response to the ABA, ethylene, methyl jasmonate, drought, cold and high-salinity treatments, indicating that the EABF and EABF1 might act as connectors among different stress signal transduction pathways. Our results indicate that the EABF and EABF1 are novel stress-responsive transcription factors, which are involved in the abiotic stress response and ABA signaling in the oil palm and could be used for production of stress-tolerant transgenic crops.
脱落酸（ABA）是一种参与植物非生物胁迫抗性的重要植物激素。ABA 响应元件（ABRE）结合因子在植物发育和对非生物胁迫的响应中发挥重要作用，但迄今为止尚未从油棕中分离和鉴定。使用酵母单杂交系统，从油棕果实中分离出两个 ABA 响应 cDNA 克隆，命名为 EABF 和 EABF1。EABF 具有保守的 AP2/EREBP DNA 结合域（DNA-BD）和潜在的核定位序列（NLS）。从 EABF1 序列中未鉴定出先前已知的 DNA-BD。根据多序列比对和系统发育分析，EABF 和 EABF1 蛋白被归类为 DREB/CBF 和 bZIP 家族成员。两种蛋白质在酵母中均显示出 ABRE 结合和转录激活特性。此外，两种蛋白质都能够在酵母中转激活 LacZ 报告基因的下游表达。电泳迁移率变动分析表明，除了 ABRE 序列外，两种蛋白质还可以与 DRE 序列结合。转录分析表明，EABF 的表达在油棕果实和叶片中受到 ABA 的诱导，但在根中不受诱导，而 EABF1 在所有组织中均持续诱导。在果实中，两种基因的表达均强烈诱导以响应 ABA、乙烯、茉莉酸甲酯、干旱、寒冷和高盐度处理，表明 EABF 和 EABF1 可能在不同的胁迫信号转导途径之间起连接作用。我们的研究结果表明，EABF 和 EABF1 是新的应激反应转录因子，参与油棕的非生物胁迫反应和 ABA 信号转导，可用于生产抗胁迫转基因作物。
