Over-Expression of ScMnSOD,a SOD Gene Derived from Jojoba,Improve Drought Tolerance in Arabidopsis

Jojoba (Simmondsia chinensis) is mainly distributed in desert, and the molecular mechanisms of jojoba in response to abiotic stress still remain elusive. In this paper, we cloned and characterized a SOD gene from jojoba named as ScMnSOD, and introduced into Arabidopsis to investigate its functions of responding to drought stress. The transgenic Arabidopsis showed an improvement in drought tolerance. Moreover, under a water deficit condition, the accumulation of reactive oxygen species (ROS) was remarkably decreased in the transgenic lines compared to the WT. Furthermore, the ScMnSOD promoter was cloned to the 5′-upstream of GUS coding region in a binary vector, and introduced into Arabidopsis. And results showed that ScMnSOD expression can be induced by drought, salt, ABA, and low temperature. In conclusion, ScMnSOD plays an important role in drought tolerance which is, at least partially, attributed to its role in ROS detoxification.     

OsMas1, a novel maspardin protein gene,confers tolerance to salt and drought stresses by regulating ABA signaling in rice

Drought and salt stresses, the major environmental abiotic stresses in agriculture worldwide, affect plant growth, crop productivity, and quality.  Therefore, developing crops with higher drought and salt tolerance is highly desirable.  This study reported the isolation, biological function, and molecular characterization of a novel maspardin gene, OsMas1, from rice.  The OsMas1 protein was localized to the cytoplasm.  The expression levels of OsMas1 were up-regulated under mannitol, PEG6000, NaCl, and abscisic acid (ABA) treatments in rice.  The OsMas1 gene was introduced into the rice cultivar Zhonghua 11 (wild type, WT).  OsMas1-overexpression (OsMas1-OE) plants exhibited significantly enhanced salt and drought tolerance; in contrast, OsMas1-interference (OsMas1-RNAi) plants exhibited decreased tolerance to salt and drought stresses, compared with WT.  OsMas1-OE plants exhibited enhanced hypersensitivity, while OsMas1-RNAi plants showed less sensitivity to exogenous ABA treatment at both germination and post-germination stages.  ABA, proline and K⁺ contents and superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and photosynthesis activities were significantly increased.  In contrast, malonaldehyde (MDA), hydrogen peroxide (H₂O₂), superoxide anion radical (O₂^-·), and Na⁺ contents were significantly decreased in OsMas1-OE plants compared with OsMas1-RNAi and WT plants.  Overexpression of OsMas1 up-regulated the genes involved in ABA signaling, proline biosynthesis, reactive oxygen species (ROS)-scavenging system, photosynthesis, and ion transport under salt and drought stresses.  Our results indicate that the OsMas1 gene improves salt and drought tolerance in rice, which may serve as a candidate gene for enhancing crop resistance to abiotic stresses.     

非生物逆境相关基因在棉花抗逆研究中的进展

非生物逆境胁迫是影响植物正常生长发育和作物产量的重要因素,为了减轻非生物逆境对棉花生长发育的影响,从分子水平上解析棉花抗逆性的物质基础及其生理功能,同时,利用基因工程手段进行抗逆性基因重组,已成为棉花抗逆研究的热点。综述了棉花对非生物逆境胁迫的抗性机制,以及近些年来有关棉花渗透调节相关基因、作用蛋白类基因和转录调节因子基因的研究进展,概述了棉花抗逆基因工程中所发掘的基因资源,旨在为今后棉花的抗逆性研究提供思路和参考依据。     

陆地棉盐胁迫应答基因GhWRKY41的克隆与分析

为研究转录因子GhWRKY41在陆地棉盐胁迫应答过程中的作用,基于差减文库分析结果,利用RT-PCR和RACE技术,克隆了GhWRKY41基因(GenBank登录号为HM002635)。该基因cDNA长度为1 630bp,含有ORF(Open reading frame)为1 068bp,编码355个氨基酸的多肽,包含2个内含子。通过瞬时表达分析亚细胞定位,结果表明,转录因子GhWRKY41定位于细胞核,符合转录因子特性。转基因株系发芽试验结果表明,过量表达GhWRKY41基因,可显著提高转基因棉花在干旱、盐和低温胁迫下的发芽率;利用Real-time PCR技术,证明在盐和干旱胁迫条件下,转基因株系中GhWRKY41基因的表达量显著上升。GhWRKY41基因在根、茎和叶片中表达存在差异,根系中胁迫6h上调达到最高,茎中则胁迫48h达到最高,而叶片中仅6和24h上调表达。进一步比较转基因棉花与野生型棉花的纤维品质性状,结果表明GhWRKY41的过表达可以提高转基因棉花的衣分。因此,GhWRKY41参与了棉花响应盐和干旱胁迫应答过程,且过表达可提高转基因棉花耐盐性和耐旱性。     

转HhERF2和PeDREB2a基因棉花对胁迫的耐受能力分析

AP2/ERF转录因子普遍存在于植物中,并广泛参与植物对生物和非生物胁迫的响应。为了提高棉花对病害及非生物逆境的抵抗能力,将分别从抗逆性优良的沙生植物铃铛刺(Halimodendron halodendron)和胡杨(Populus euphratica)中分离的HhERF2和PeDREB2a转录因子基因构建以rd29A为启动子的表达载体,并通过花粉管通道法转化棉花。利用Real-time PCR分析胁迫处理的转基因阳性植株HhERF2和PeDREB2a基因异位表达及下游PR(pathogenesis-related protein)基因表达情况,结果表明在病原菌、干旱和盐胁迫下转基因植株体内HhERF2基因能够超表达,而PeDREB2a基因仅在干旱和盐胁迫诱导下超表达。接种大丽轮枝菌(Verticillium dahlia)后能够诱导转基因植株相关PR基因表达,同时与对照J12相比植株体内PAL、SOD和POD等酚类代谢相关酶的活性显著增加,且增强了转基因棉花对大丽轮枝菌的抵抗能力。干旱和高盐胁迫下生理生化特性分析表明,与对照相比,转基因棉花叶片中可溶性碳水化合物和相对含水量显著升高,而电导率和丙二醛(MDA)含量显著降低。因此,转基因棉花对大丽轮枝菌及干旱和高盐胁迫表现出了较强的耐受能力。     

棉花抗逆性鉴定技术标准体系的建立

棉花是中国主要的经济作物,分布区域广,生产周期长,受生态逆境胁迫影响大。培育和筛选抗逆性强的棉花品种是减少逆境灾害的主要途径,而研究棉花品种的抗逆性鉴定技术和标准是至关重要的基础工作。归纳了近年来国内外作物抗逆性鉴定的基本方法,分析了棉花干旱、渍涝、盐碱、高温热害和低温冻害冷害等5种常发易发非生物逆境（生态逆境）抗逆性鉴定的鉴定时期、鉴定方法、鉴定指标和抗逆性判定级别等,总结了抗逆性鉴定标准制定和标准体系建立的基本原则、框架和内容等。提出了进一步研究的基本思路,主要包括：研究基于光谱/高光谱等新技术的快速便捷无损抗逆性鉴定、复合逆境下抗逆性鉴定、利用分子生物学手段直接找出相关抗逆基因并以此来进行抗逆性鉴定等技术。     

Genome-wide identification and characterization of the JAZ gene family and its expression patterns under various abiotic stresses in Sorghum bicolor

The jasmonate ZIM domain (JAZ) protein belongs to the TIFY ((TIF[F/Y]XG) domain protein) family, which is composed of several plant-specific proteins that play important roles in plant growth, development, and defense responses. However, the mechanism of the sorghum JAZ family in response to abiotic stress remains unclear. In the present study, a total of 17 JAZ genes were identified in sorghum using a Hidden Markov Model search. In addition, real-time quantification polymerase chain reaction (RT-qPCR) was used to analyze the gene expression patterns under abiotic stress. Based on phylogenetic tree analysis, the sorghum JAZ proteins were mainly divided into nine subfamilies. A promoter analysis revealed that the SbJAZ family contains diverse types of promoter cis-acting elements, indicating that JAZ proteins function in multiple pathways upon stress stimulation in plants. According to RT-qPCR, SbJAZ gene expression is tissue-specific. Additionally, under cold, hot, polyethylene glycol, jasmonic acid, abscisic acid, and gibberellin treatments, the expression patterns of SbJAZ genes were distinctly different, indicating that the expression of SbJAZ genes may be coordinated with different stresses. Furthermore, the overexpression of SbJAZ1 in Escherichia coli was found to promote the growth of recombinant cells under abiotic stresses, such as PEG 6000, NaCl, and 40°C treatments. Altogether, our findings help us to better understand the potential molecular mechanisms of the SbJAZ family in sorghum in response to abiotic stresses.     

Multi-functional roles of TaSSI2 involved in Fusarium head blight and powdery mildew resistance and drought tolerance

The mutation of the gene encoding a stearoyl-acyl carrier protein fatty acid desaturase (ssi2) has been proved to enhance pathogen resistance in several plants, while it's potential to regulate biotic and abiotic stresses in wheat is still unclear. In this study, we cloned TaSSI2 gene in wheat and provided several evidences of its involvement in multiple biological functions. By using barley stripe mosaic virus (BSMV)-induced gene silencing (VIGS) in wheat, it was found that TaSSI2 negatively regulated both powdery mildew and Fusarium head blight (FHB) resistance, which was consistent with the phenotype observed in knock-out mutants of Kronos. The expression of TaSSI2 was down-regulated by in vitro treatments of methyl jasmonate (MeJA), but positively regulated by salicylic acid (SA) and abscisic acid (ABA), implying the cross-talk between different hormone signaling pathways involved in wheat to regulate biotic stresses is still to be elucidated. Furthermore, the up-regulated expression of PR4 and PR5 indicated that TaSSI2 probably regulated FHB resistance by depressing the SA signaling pathway in wheat. In addition, the over-expression of TaSSI2 increased the content of linolenic acid (18:3) and subsequently enhanced drought tolerance of transgenic Brachypodium. This phenomenon might be associated with its subcellular localization in the whole cytosol, partly overlapping with Golgi apparatus and the secreted vesicles. As a stearoyl-acyl carrier protein fatty acid desaturase, TaSSI2 was proposed to be involved in cell lipid metabolism and carried targets out of the cell from membrane or wax synthesis, resulting in enhanced drought tolerance in plant.     

A novel aldo-keto reductase gene, IbAKR, from sweet potato confers higher tolerance to cadmium stress in tobacco

High concentrations of Cd can inhibit growth and reduce the activity of the photosynthetic apparatus in plants. In several plant species, aldo-keto reductases (AKRs) have been shown to enhance tolerance to various abiotic stresses by scavenging cytotoxic aldehydes; however, few AKRs have been reported to enhance Cd stress tolerance. In this study, the gene IbAKR was isolated from sweet potato. The relative expression levels of IbAKR increased significantly (approximately 3-fold) after exposure to 200 mmol·L⁻¹ CdCl₂ or 10 mmol·L⁻¹ H₂O₂. A subcellular localization assay showed that IbAKR is predominantly located in the nucleus and cytoplasm. IbAKR-overexpressing tobacco plants showed higher tolerance to Cd stress than wild-type (WT). Transgenic lines showed a significant ability to scavenge malondialdehyde (MDA) and methylglyoxal (MG). In addition, proline content and superoxide dismutase activity were significantly higher and H₂O₂ levels were significantly lower in the transgenic plants than in the WT. Quantitative real-time PCR analysis showed that the reactive oxygen species (ROS) scavenging genes encoding guaiacol peroxidase (GPX), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) and peroxidase (POD) were significantly upregulated in transgenic plants compared to WT under Cd stress. These findings suggest that overexpressing IbAKR enhances tolerance to Cd stress via the scavenging of cytotoxic aldehydes and the activation of the ROS scavenging system.     

非生物胁迫下植物体内活性氧和丙酮醛代谢的研究进展

活性氧（ROS）和丙酮醛（MG）是植物响应非生物胁迫过程中不可或缺的组成部分。低剂量的ROS或MG参与信号交流、种子萌发、植物生长发育及非生物胁迫应答等过程，而过量的ROS或MG具有高反应性和细胞毒性，会导致植物处于氧化胁迫或MG胁迫状态。为了维持植株体内ROS和MG的动态平衡，植物自身进化出了一系列的ROS和MG产生及清除机制。文章归纳总结了植物体内ROS和MG的合成代谢过程、分解代谢过程以及两者合成和分解代谢间的关系，阐明了不同非生物胁迫 （干旱、温度、盐、碱、盐碱和重金属胁迫）条件下植物体内ROS和MG代谢间的调节情况。提出今后应加强植物体内MG的信号作用、乙二醛酶系统响应非生物胁迫的机理以及乙二醛酶系统耐逆基因工程开发的深入研究，以期为非生物胁迫下植物体内ROS和MG代谢机制的深入研究提供借鉴。     

AP2/ERF蛋白调控植物的非生物胁迫应答机制

AP2/ERF蛋白是植物所特有的转录因子,参与植物生长发育以及调控生物和非生物胁迫反应。研究表明,AP2/ERF蛋白不仅与其它类型转录因子共同形成复杂的转录调控网络,通过多种信号转导途径调控功能基因的表达,而且可以作为外界信号的感应因子调控植物的非生物胁迫应答。主要从AP2/ERF蛋白在植物激素合成、蜡质合成、低氧胁迫应答、ROS清除以及蛋白质修饰等方面综述了AP2/ERF蛋白在植物非生物胁迫应答中的研究进展,并展望了今后的研究方向。     

胡杨PePEX11基因参与调节盐胁迫下拟南芥的抗氧化能力

目的长期非生物逆境胁迫下,植物会产生过量活性氧并造成氧化损伤,过氧化物酶体能够通过清除活性氧来调节氧化还原平衡。PEX基因参与过氧化物酶体的生物发生和增殖,PEX11基因的过表达可促进过氧化物酶体增殖,对植物的抗氧化能力的提升具有重要意义。胡杨是研究木本植物中抗逆机制优良材料,本文旨在探究胡杨PEX11基因对非生物胁迫的响应。方法本研究首先以胡杨叶片cDNA为模板克隆获得PEX11基因,命名为PePEX11,并对PePEX11蛋白进行生物信息学分析,其次采用实时荧光定量PCR分析PePEX11在胡杨中的表达模式,同时构建植物表达pCAMBIA1301-35S::PePEX11转化拟南芥,最后检测盐胁迫条件下转PePEX11拟南芥的抗氧化能力。结果PePEX11基因cDNA全长543 bp,编码180个氨基酸,PePEX11蛋白具有多个跨膜结构域,在膜上发挥作用。实时荧光定量PCR分析表明,该基因在胡杨体的成熟叶中表达量最高,幼叶次之,茎中最少;胡杨PePEX11基因受盐胁迫上调表达。功能分析显示,在含有100 mmol/L NaCl的培养基上,转PePEX11基因拟南芥株系的根长均显著长于野生型;对盆土中的移栽后12 d的幼苗150 mmol/L NaCl盐处理2周,转基因株系表现为营养生长良好,耐盐性较强。超表达PePEX11基因能显著提高(P＜0.05)拟南芥多种抗氧化酶的活性。DAB组织染色结果表明,转基因株系叶片中H₂O₂的含量明显少于野生型。结论本研究从胡杨中克隆PePEX11基因,并证明PePEX11能够提高拟南芥在盐胁迫下的抗氧化能力,提升耐盐能力。