Li Shixue, Zhao Qian, Zhu Dengyun, Yu Jingjuan
State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China.
Front Plant Sci. 2018 Apr 4;9:395. doi: 10.3389/fpls.2018.00395. eCollection 2018.
The DREB (dehydration-responsive element binding)-type transcription factors are classified into six subgroups, named A-1 to A-6. The members of DREB A-1 and A-2 subgroups have been reported to be involved in response to various abiotic stresses. However, there were only a few genes belonging to A-3 to A-6 subgroups to be reported. In this study, we cloned a DREB A-4 subgroup gene from maize (), , and analyzed its characteristics and functions. was expressed in roots, stems, and leaves at very low levels. It was not induced by any biotic or abiotic treatment. ZmDREB4.1 was located in the nucleus, could directly bind to the DRE element and functioned as a transcriptional activator. The constitutive expression of in tobacco ( L.) repressed leaf extension and hypocotyl, petiole and stem elongation. In maize, overexpression of repressed calli growth and regeneration. Further analysis showed that the smaller leaves of transgenic tobacco resulted from inhibition of cell division. The contents of cytokinin and auxin in transgenic leaves were severely decreased. The shorter hypocotyls, stems and petioles of transgenic tobacco were caused by inhibition of cell elongation. The transgenic hypocotyls, stems and petioles contained reduced gibberellin levels. Application of exogenous GA3 rescued the shorter hypocotyls, stems and petioles, but not the smaller leaves. These results demonstrated that plays an important role in the negative regulation of plant growth and development.
DREB（脱水响应元件结合）型转录因子分为六个亚组，命名为A-1至A-6。据报道，DREB A-1和A-2亚组的成员参与对各种非生物胁迫的响应。然而，属于A-3至A-6亚组的基因报道较少。在本研究中，我们从玉米中克隆了一个DREB A-4亚组基因（），并分析了其特征和功能。（该基因名称缺失）在根、茎和叶中表达水平极低。它不受任何生物或非生物处理的诱导。ZmDREB4.1定位于细胞核，可直接与DRE元件结合并作为转录激活因子发挥作用。（该基因名称缺失）在烟草（烟草属）中的组成型表达抑制了叶片伸展以及下胚轴、叶柄和茎的伸长。在玉米中，（该基因名称缺失）的过表达抑制了愈伤组织的生长和再生。进一步分析表明，转基因烟草叶片变小是由于细胞分裂受到抑制。转基因叶片中细胞分裂素和生长素的含量大幅降低。转基因烟草下胚轴、茎和叶柄变短是由于细胞伸长受到抑制。转基因下胚轴、茎和叶柄中的赤霉素水平降低。施加外源GA3挽救了下胚轴、茎和叶柄变短的情况，但没有挽救叶片变小的情况。这些结果表明（该基因名称缺失）在植物生长发育的负调控中起重要作用。
