Gutha Linga Reddy, Reddy Arjula R
Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.
Plant Mol Biol. 2008 Dec;68(6):533-55. doi: 10.1007/s11103-008-9391-8. Epub 2008 Aug 28.
CBF/DREB (C-repeat binding factor/dehydration responsive element binding factor) family of transcription factors in plants is reported to be associated with regulation of gene expression under stress conditions. Here, we report the functional characterization of a DREB transcription factor, DREB1B gene from rice (Oryza sativa ssp. indica). The OsDREB1B gene was differentially regulated at the transcriptional level by osmotic stress, oxidative stress, salicylic acid, ABA, and cold. A 745 bp promoter region of OsDREB1B cDNA was fused to the beta-glucuronidase (GUS) gene and introduced via Agrobacterium tumifaciens into the genome of Arabidopsis. Histochemical analysis of GUS expression in T(2) transgenic Arabidopsis plants indicated that OsDREB1B shows stress-specific induction pattern in response to a variety of stresses like mannitol, NaCl, PEG, methyl viologen, cold, ABA, and salicylic acid. Leaf-order-dependent induction pattern of the promoter was observed in response to both cold and ABA stresses. Further, OsDREB1B cDNA was introduced into tobacco plants under the control of CaMV35S promoter to investigate the role of DREB1B product in plant stress response. Transgenic tobacco plants have shown improved seed germination, root growth, membrane stability, and 2, 2-diphenyl-1-pycrilhydrazil hydrate (DPPH) free radical scavenging activity under inhibitory concentrations of mannitol. Importantly, transgenic plants accumulated higher fresh weight under long-term osmotic stress, and also have shown retention of more water than the wild type during drought stress. Overexpression of OsDREB1B in tobacco also improved the oxidative and freezing stress tolerance of transgenic plants. In addition, tobacco plants constitutively expressing OsDREB1B have shown decreased sensitivity to tobacco streak virus infection. Constitutive expression of OsDREB1B in tobacco also induced the expression of PR genes in transgenic plants. The data obtained provide strong in vivo evidence that OsDREB1B is involved in both abiotic and biotic stress responses, and confers broad-spectrum stress tolerance to transgenic plants.
据报道，植物中的CBF/DREB（C-重复结合因子/脱水响应元件结合因子）转录因子家族与胁迫条件下的基因表达调控有关。在此，我们报道了来自水稻（Oryza sativa ssp. indica）的一个DREB转录因子DREB1B基因的功能特性。OsDREB1B基因在转录水平上受到渗透胁迫、氧化胁迫、水杨酸、脱落酸和低温的差异调控。将OsDREB1B cDNA的745 bp启动子区域与β-葡萄糖醛酸酶（GUS）基因融合，并通过根癌农杆菌导入拟南芥基因组。对T(2)转基因拟南芥植株中GUS表达的组织化学分析表明，OsDREB1B在响应甘露醇、氯化钠、聚乙二醇、甲基紫精、低温、脱落酸和水杨酸等多种胁迫时表现出胁迫特异性诱导模式。在响应低温和脱落酸胁迫时，观察到启动子的叶序依赖性诱导模式。此外，将OsDREB1B cDNA在CaMV35S启动子的控制下导入烟草植株，以研究DREB1B产物在植物胁迫响应中的作用。转基因烟草植株在甘露醇抑制浓度下表现出种子萌发、根系生长、膜稳定性和2,2-二苯基-1-吡啶基肼水合物（DPPH）自由基清除活性的改善。重要的是，转基因植株在长期渗透胁迫下积累了更高的鲜重，并且在干旱胁迫期间比野生型保留了更多的水分。OsDREB1B在烟草中的过表达还提高了转基因植株的氧化和冷冻胁迫耐受性。此外，组成型表达OsDREB1B的烟草植株对烟草条纹病毒感染的敏感性降低。OsDREB1B在烟草中的组成型表达还诱导了转基因植株中PR基因的表达。获得的数据提供了强有力的体内证据，表明OsDREB1B参与非生物和生物胁迫响应，并赋予转基因植株广谱胁迫耐受性。
