OsLEA3-2, an Abiotic Stress Induced Gene of Rice Plays a Key Role in Salt and Drought Tolerance

Late embryogenesis abundant (LEA) proteins are involved in tolerance to drought, cold and high salinity in many different organisms. In this report, a LEA protein producing full-length gene OsLEA3-2 was identified in rice (Oryza sativa) using the Rapid Amplification of cDNA Ends (RACE) method. OsLEA3-2 was found to be only expressed in the embryo and can be induced by abiotic stresses. The coding protein localizes to the nucleus and overexpression of OsLEA3-2 in yeast improved growth performance compared with control under salt- and osmotic-stress conditions. OsLEA3-2 was also inserted into pHB vector and overexpressed in Arabidopsis and rice. The transgenic Arabidopsis seedlings showed better growth on MS media supplemented with 150 mM mannitol or 100 mM NaCl as compared with wild type plants. The transgenic rice also showed significantly stronger growth performance than control under salinity or osmotic stress conditions and were able to recover after 20 days of drought stress. In vitro analysis showed that OsLEA3-2 was able to protect LDH from aggregation on freezing and inactivation on desiccation. These results indicated that OsLEA3-2 plays an important role in tolerance to abiotic stresses.     

The Negative Regulator OsSDS1 Significantly Reduces Salt and Drought Tolerance in Transgenic Arabidopsis

In this report, we present data on OsSDS1 (Oryza sativa L. salt and drought sensitive gene 1)—an uncharacterized gene isolated from rice Pei’ai 64S (O. sativa L.). Expression of OsSDS1 was strongly up-regulated by a wide spectrum of stresses, including cold, drought, and heat, in different tissues at different developmental stages of rice, as revealed by both microarray and quantitative RT-PCR analyses. Subcellular localization revealed that an OsSDS1: GFP fusion protein was distributed to the nucleus. Expression of OsSDS1 conferred decreased tolerance to salt and drought in Arabidopsis thaliana, accompanied by altered expression of stress-responsive genes and altered K⁺/Na⁺ ratio. The results suggest that OsSDS1 may act as a negative regulator of salt and drought tolerance in plants.     

Wheat V-H+-ATPase Subunit Genes Significantly Affect Salt Tolerance in Arabidopsis thaliana

Genes for V-H⁺-ATPase subunits were identified and cloned from the salt-tolerant wheat mutant RH8706-49. Sequences of these genes are highly conserved in plants. Overexpression of these genes in Arabidopsis thaliana improved its salt tolerance, and increased the activities of V-H⁺-ATPase and Na⁺/H⁺ exchange, with the largest increase in plants carrying the c subunit of V-H⁺-ATPase. Results from quantitative RT-PCR analysis indicated that the mRNA level of each V-H⁺-ATPase subunit in the Arabidopsis increased under salt stress. Overall, our results suggest that each V-H⁺-ATPase subunit plays a key role in enhancing salt tolerance in plants.     

A Soybean C2H2-Type Zinc Finger Gene GmZF1 Enhanced Cold Tolerance in Transgenic Arabidopsis

Zinc finger proteins were involved in response to different environmental stresses in plant species. A typical Cys2/His2-type (C2H2-type) zinc finger gene GmZF1 from soybean was isolated and was composed of 172 amino acids containing two conserved C2H2-type zinc finger domains. Phylogenetic analysis showed that GmZF1 was clustered on the same branch with six C2H2-type ZFPs from dicotyledonous plants excepting for GsZFP1, and distinguished those from monocotyledon species. The GmZF1 protein was localized at the nucleus, and has specific binding activity with EP1S core sequence, and nucleotide mutation in the core sequence of EPSPS promoter changed the binding ability between GmZF1 protein and core DNA element, implying that two amino acid residues, G and C boxed in core sequence TGACAGTGTCA possibly play positive regulation role in recognizing DNA-binding sites in GmZF1 proteins. High accumulation of GmZF1 mRNA induced by exogenous ABA suggested that GmZF1 was involved in an ABA-dependent signal transduction pathway. Over-expression of GmZF1 significantly improved the contents of proline and soluble sugar and decreased the MDA contents in the transgenic lines exposed to cold stress, indicating that transgenic Arabidopsis carrying GmZF1 gene have adaptive mechanisms to cold stress. Over-expression of GmZF1 also increased the expression of cold-regulated cor6.6 gene by probably recognizing protein-DNA binding sites, suggesting that GmZF1 from soybean could enhance the tolerance of Arabidopsis to cold stress by regulating expression of cold-regulation gene in the transgenic Arabidopsis.     

辣椒CaNAC36转录因子耐盐性分析

【目的】辣椒是中国种植面积最大的蔬菜作物,随着土地盐碱化问题的日趋严重,加强辣椒耐盐机制研究对促进产业可持续发展具有重要意义。因而,急需加快辣椒耐盐相关关键基因的功能研究。【方法】研究组前期挖掘到与辣椒耐盐性相关的转录因子CaNAC36,在此基础上,以耐盐辣椒PI201224和敏盐辣椒PI438643为供试品种,克隆获得CaNAC36全长gDNA和cDNA序列,通过荧光定量分析CaNAC36及可能的互作基因在盐胁迫条件下不同组织部位的表达情况,并进一步结合生物信息学分析探究CaNAC36及其互作基因之间存在的潜在关系。【结果】结果表明,CaNAC36序列在耐盐和敏盐材料中DNA和cDNA同源性分别为99.86%和100%;荧光定量的结果表明,CaNAC36在耐盐材料根和茎组织中表现为诱导上调表达,在敏盐材料根和叶中表现为诱导下调表达;对可能与CaNAC36存在互作关系的48个基因的注释信息进行分析后,发现跨膜蛋白、转运蛋白、水孔蛋白、氯离子通道蛋白、解毒蛋白等14个基因可能与CaNAC36存在功能互作。进一步分析发现,在PI201224和PI438643盐胁迫处理不同时间点、不同组织中,5个相关基因（Capana08g002748、Capana00g004514、Capana09g000275、Capana07g001450、Capana02g001031）的表达呈现显著差异。同时发现,CaNAC36及5个关联基因启动子域含有大量的逆境相关顺式作用元件。【结论】结合基因克隆、基因表达水平分析以及生物信息学分析,表明CaNAC36是辣椒响应盐胁迫的重要转录因子,并可能与其他基因相互作用以提高植株的耐盐性,可为深度研究辣椒耐盐性以及选育耐盐品种提供数据支撑。     

Floral-dip法大豆GmDREB转录因子转拟南芥研究

DREB（dehydration responsive element binding）转录因子通过调控下游多个抗逆相关基因的表达,能有效提高植物的抗逆性。将构建的植物高效表达载体GmDREB：：pCAMBIA1304,借助优化的floral-dip法,转入模式植物拟南芥,并经潮霉素Hygromycine（40-50mg·L^-1）抗性筛选得到22棵抗性植株。对抗性植株再进行PCR和GUS检测获得19颗阳性苗,阳性率为86．3％。对T1代种子进行抗性分离比例统计,有4个株系的分离比例接近3：1,符合孟德尔遗传定律,说明外源基因GmDREB在这些株系的染色体中可能是单拷贝插入。继续对上述4个株系的后代进行抗性筛选．现已得到2个纯合的转基因株系。导入的报告基因GUS组织染色检测表明,转入大豆DREB基因在拟南芥的根系和子叶中均有大量表达,并在叶脉中表达。