Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.
Plant Mol Biol. 2011 Jan;75(1-2):107-27. doi: 10.1007/s11103-010-9711-7. Epub 2010 Nov 11.
APETALA2 (AP2) transcription factors (TFs) play very important roles in plant growth and development and in defense response. Here, we report functional characterization of four AP2 TF family genes [(RAP2.6 (At1g43160), RAP2.6L (At5g13330), DREB 26 (At1g21910) and DREB19 (At2g38340)] that were identified among NaCl inducible transcripts in abscisic acid responsive 17 (ABR17) transgenic Arabidopsis in our previous microarray analyses. DREB19 and DREB26 function as transactivators and localize in the nucleus. All four genes were abundant in early vegetative and flowering stages, although the magnitude of the expression varied. We observed tissue specific expression patterns for RAP2.6, RAP2.6L, DREB19 and DREB26 in flowers and other organs. RAP2.6 and RAP2.6L were responsive to stress hormones like jasmonic acid, salicylic acid, abscisic acid and ethylene in addition to salt and drought. DREB19 and DREB26 were less responsive to stress hormones, but the former was highly responsive to salt, heat and drought. Overexpression of RAP2.6 in Arabidopsis resulted in a dwarf phenotype with extensive secondary branching and small siliques, and DREB26 overexpression resulted in deformed plants. However, overexpression of RAP2.6L and DREB19 enhanced performance under salt and drought stresses without affecting phenotype. In summary, we have demonstrated that RAP2.6, RAP2.6L, DREB26 and DREB19 are transactivators, they exhibit tissue specific expression, and they participate in plant developmental processes as well as biotic and/or abiotic stress signaling. It is possible that the results from this study on these transcription factors, in particular RAP2.6L and DREB19, can be utilized in developing salt and drought tolerant plants in the future.
APETALA2 (AP2) 转录因子 (TFs) 在植物生长发育和防御反应中发挥着非常重要的作用。在这里，我们报告了四个 AP2 TF 家族基因 [(RAP2.6 (At1g43160)、RAP2.6L (At5g13330)、DREB 26 (At1g21910) 和 DREB19 (At2g38340)] 的功能特征，这些基因是我们之前在 microarray 分析中在盐诱导的拟南芥 abscisic acid responsive 17 (ABR17) 转基因中鉴定的转录本。DREB19 和 DREB26 作为转录激活因子发挥作用，并定位于细胞核中。尽管表达量有所不同，但这四个基因在早期营养生长和开花阶段都很丰富。我们观察到 RAP2.6、RAP2.6L、DREB19 和 DREB26 在花和其他器官中的组织特异性表达模式。RAP2.6 和 RAP2.6L 除了对盐和干旱有反应外，还对茉莉酸、水杨酸、脱落酸和乙烯等应激激素有反应。DREB19 和 DREB26 对应激激素的反应性较低，但前者对盐、热和干旱的反应性较高。在拟南芥中过表达 RAP2.6 导致矮化表型，具有广泛的次生分枝和小的蒴果，而过表达 DREB26 导致植物变形。然而，过表达 RAP2.6L 和 DREB19 增强了在盐和干旱胁迫下的表现，而不影响表型。总之，我们已经证明 RAP2.6、RAP2.6L、DREB26 和 DREB19 是转录激活因子，它们表现出组织特异性表达，并参与植物发育过程以及生物和/或非生物胁迫信号转导。在未来，对这些转录因子，特别是 RAP2.6L 和 DREB19 的研究结果可能用于开发耐盐和耐旱植物。
