过表达SmERF1提高了丹参耐盐性

ERF(ethylene-responsive factor)蛋白是植物中一大类转录因子家族,在植物的生长发育及逆境胁迫中发挥着重要作用.为研究丹参中新的转录因子SmERF1的功能,本研究对其编码序列、表达模式进行分析,并在丹参中进行过表达,检测过表达后转基因植株耐盐性、次生代谢物和激素的变化.研究结果表明,SmERF1含有一个AP2结构域,是典型的ERF转录因子.SmERF1受到MeJA和酵母诱导子(YE)的诱导表达.在盐胁迫下,过表达SmERF1的丹参株系中脯氨酸含量、SOD和POD活性较野生型丹参植株高,MDA含量降低,说明转基因株系的抗盐特性增强.而且过表达SmERF1的丹参株系中ABA含量升高,GA含量降低;过表达SmERF1对丹参酮、丹酚酸等代谢物的合成调控效果不强.综合以上结果,表明SmERF1可能通过调节ABA的合成,提高了丹参耐盐性.     

过量表达棉花GaSus3基因增强拟南芥的耐盐性

构建了植物过量表达载体p35S：：GaSus3,通过花序浸染法成功获得转GaSus3基因拟南芥植株。利用NaCl模拟盐胁迫处理,证实转基因拟南芥与野生型相比耐盐性明显增强。在盐胁迫下,转基因拟南芥受到的影响较小,而野生型则受盐害影响严重：转基因拟南芥具有更好的萌发率和主根长度,以保证植株正常生长;盐胁迫下转基因拟南芥能保持较多的绿色叶片,而野生型则过早黄化死亡。研究还发现,转基因拟南芥的过氧化氢酶活性在胁迫前后都高于野生型,这说明转GaSus3基因能够提高拟南芥抗氧化胁迫的能力。研究结果为进一步探讨GaSus3基因在棉花耐盐方面的功能奠定了基础。     

过量表达星星草PtSOS_1提高拟南芥的耐盐性

将星星草中分离的质膜型Na+/H+逆向转运蛋白基因PtSOS1(GenBank登录号EF440291)构建到pGWB2植物表达载体上,转化拟南芥,获得抗卡那霉素的抗性植株.PCR和Northern检测表明,PtSOS1已整合到拟南芥基因组中并过量表达.耐盐性实验表明,PtSOS1过量表达提高了拟南芥植株的耐盐性.盐分测定表明,盐胁迫下PtSOS1转基因植株中Na+积累低于野生型的,K+含量则高于野生型的,转基因植株中K+/Na+比值高于野生型.     

Overexpression of Small Heat Shock Protein LimHSP16.45 in Arabidopsis Enhances Tolerance to Abiotic Stresses

Small heat shock proteins (smHSPs) play important and extensive roles in plant defenses against abiotic stresses. We cloned a gene for a smHSP from the David Lily (Lilium davidii (E. H. Wilson) Raffill var. Willmottiae), which we named LimHSP16.45 based on its protein molecular weight. Its expression was induced by many kinds of abiotic stresses in both the lily and transgenic plants of Arabidopsis. Heterologous expression enhanced cell viability of the latter under high temperatures, high salt, and oxidative stress, and heat shock granules (HSGs) formed under heat or salinity treatment. Assays of enzymes showed that LimHSP16.45 overexpression was related to greater activity by superoxide dismutase and catalase in transgenic lines. Therefore, we conclude that heterologous expression can protect plants against abiotic stresses by preventing irreversible protein aggregation, and by scavenging cellular reactive oxygen species.     

新牧一号杂花苜蓿MvNHX1基因的表达分析和提高烟草耐盐性的研究

提取新牧一号杂花苜蓿的总RNA,用特异引物RT-PCR扩增后的cDNA片段连接入pMD19-T载体,转化大肠杆菌DH5α,对阳性克隆进行序列分析,新牧一号苜蓿NHX1（MvNHX1）全长1 626 bp,Genbank登录号为：EU375310。半定量RT-PCR和实时荧光定量PCR分析表明,在盐胁迫下MvNHX1基因的表达均上调。构建重组植物表达载体pBI121-MvNHX1后,通过农杆菌介导的叶盘法转化烟草,转基因烟草在盐胁迫下发芽率和生物量均高于非转基因烟草,表明MvNHX1能够提高转基因烟草的耐盐性。     

超表达AVP1基因提高转基因百脉根的耐盐性和抗旱性

本研究以超表达拟南芥液泡膜H＋-焦磷酸酶编码基因AVPI的转基因百脉根为材料,对其耐盐性和抗旱性进行了检测。结果显示：在200mmol·L^-1 NaCl下处理或自然干旱7d后,转基因植株的生长虽然受到抑制,但受抑程度明显低于野生型植株,前者叶片相对含水量比后者分别高18％和14％,净光合速率分别高20％和21％,而MDA含量则分别低35％和27％,相对质膜透性分别低28％和27％。此外,随着盐和干旱胁迫的加剧,与野生型植株相比,转基因植株体内积累了更多Na＋、K＋和Ca2＋。以上结果表明,AVPI基因的超表达可能提高了百脉根细胞Na＋区域化能力,既减轻了过量Na＋对细胞质的毒害作用,也提高了植株的渗透调节能力,从而增强了百脉根的耐盐性和抗旱性。     

ERF类转录因子OPBP1基因的超表达提高烟草的耐盐能力

ERF是植物中的一类重要的转录因子,参与调节植物的生长,发育以及抗胁迫等过程,对一烟草OPBP1基因（属于ERF类基因）的烟草转化,获得了该基因超表达的植株,转基因植株明显地增加了耐盐能力,Northern杂交结果表明,OPBP1基因有不同程度的表达,而且表达丰度与其耐盐性有一定的正相关性,凝胶阻滞实验结果证明OPBP1融合蛋白能特异地与含GCC盒的DNA序列结合,这些结果说明OPBP1基因可能作为一转录因子来调节烟草耐盐相关的基因。     

High Tolerance to Salinity and Herbivory Stresses May Explain the Expansion of Ipomoea Cairica to Salt Marshes

Background

Invasive plants are often confronted with heterogeneous environments and various stress factors during their secondary phase of invasion into more stressful habitats. A high tolerance to stress factors may allow exotics to successfully invade stressful environments. Ipomoea cairica, a vigorous invader in South China, has recently been expanding into salt marshes.

Methodology/Principal Findings

To examine why this liana species is able to invade a stressful saline environment, we utilized I. cairica and 3 non-invasive species for a greenhouse experiment. The plants were subjected to three levels of salinity (i.e., watered with 0, 4 and 8 g L⁻¹ NaCl solutions) and simulated herbivory (0, 25 and 50% of the leaf area excised) treatments. The relative growth rate (RGR) of I. cairica was significantly higher than the RGR of non-invasive species under both stress treatments. The growth performance of I. cairica was not significantly affected by either stress factor, while that of the non-invasive species was significantly inhibited. The leaf condensed tannin content was generally lower in I. cairica than in the non-invasive I. triloba and Paederia foetida. Ipomoea cairica exhibited a relatively low resistance to herbivory, however, its tolerance to stress factors was significantly higher than either of the non-invasive species.

Conclusions/Significance

This is the first study examining the expansion of I. cairica to salt marshes in its introduced range. Our results suggest that the high tolerance of I. cairica to key stress factors (e.g., salinity and herbivory) contributes to its invasion into salt marshes. For I. cairica, a trade-off in resource reallocation may allow increased resources to be allocated to tolerance and growth. This may contribute to a secondary invasion into stressful habitats. Finally, we suggest that I. cairica could spread further and successfully occupy salt marshes, and countermeasures based on herbivory could be ineffective for controlling this invasion.     

Overexpression of WsSGTL1 Gene of Withania somnifera Enhances Salt Tolerance,Heat Tolerance and Cold Acclimation Ability in Transgenic Arabidopsis Plants

Background

Sterol glycosyltrnasferases (SGT) are enzymes that glycosylate sterols which play important role in plant adaptation to stress and are medicinally important in plants like Withania somnifera. The present study aims to find the role of WsSGTL1 which is a sterol glycosyltransferase from W. somnifera, in plant’s adaptation to abiotic stress.

Methodology

The WsSGTL1 gene was transformed in Arabidopsis thaliana through Agrobacterium mediated transformation, using the binary vector pBI121, by floral dip method. The phenotypic and physiological parameters like germination, root length, shoot weight, relative electrolyte conductivity, MDA content, SOD levels, relative electrolyte leakage and chlorophyll measurements were compared between transgenic and wild type Arabidopsis plants under different abiotic stresses - salt, heat and cold. Biochemical analysis was done by HPLC-TLC and radiolabelled enzyme assay. The promoter of the WsSGTL1 gene was cloned by using Genome Walker kit (Clontech, USA) and the 3D structures were predicted by using Discovery Studio Ver. 2.5.

Results

The WsSGTL1 transgenic plants were confirmed to be single copy by Southern and homozygous by segregation analysis. As compared to WT, the transgenic plants showed better germination, salt tolerance, heat and cold tolerance. The level of the transgene WsSGTL1 was elevated in heat, cold and salt stress along with other marker genes such as HSP70, HSP90, RD29, SOS3 and LEA4-5. Biochemical analysis showed the formation of sterol glycosides and increase in enzyme activity. When the promoter of WsSGTL1 gene was cloned from W. somnifera and sequenced, it contained stress responsive elements. Bioinformatics analysis of the 3D structure of the WsSGTL1 protein showed functional similarity with sterol glycosyltransferase AtSGT of A. thaliana.

Conclusions

Transformation of WsSGTL1 gene in A. thaliana conferred abiotic stress tolerance. The promoter of the gene in W.somnifera was found to have stress responsive elements. The 3D structure showed functional similarity with sterol glycosyltransferases.     

棉花两品种耐盐性与抗氧化能力的相关性

对‘新陆早17’和‘中棉49’两个棉花（Gossypium hirsutumL.）品种在氧化剂甲基紫精（MV）和NaCl胁迫下的生理应答进行了研究,以期阐明棉花抗氧化能力与耐盐性的关系。研究结果表明,在40μmol·L-1MV胁迫3d,‘新陆早17’的丙二醛（MDA）和活性氧含量比‘中棉49’低,而抗坏血酸（AsA）、超氧化物岐化酶（SOD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）活性则高于‘中棉49’,表明‘新陆早17’抗氧化能力更强。在200mmol·L-1NaCl胁迫25d,‘新陆早17’的株高和叶绿素降低量、根部Na＋含量、相对电导率都低于‘中棉49’,说明‘新陆早17’耐盐更强。盐胁迫下‘新陆早17’的抗氧化酶活性上升而‘中棉49’却降低,表明‘新陆早17’通过上调SOD、CAT和APX活性来提高其耐盐性。结合棉花两品种的抗氧化和耐盐性差异,说明棉花抗氧化能力的高低能够影响品种的耐盐性。     

拟南芥CBF1与植物对低温和干旱的抗性

对冷驯化过程中基因表达差异的认识,使抗冻基因(COR)的克隆及其功能的分析成为研究冷驯化过程的主要目标。在拟南芥和其他抗冻植物中,分离了许多COR基因,这些基因对植物抗冻起着非常重要的作用。在拟南芥COR调控的研究中,发现了CBF转录因子的基因家族,其中CBF1能调控一组COR基因的表达。近年来,在冷敏植物如番茄和玉米中也发现了CBF类似基因,拟南芥CBF1基因在转基因番茄中的过量表达提高了植株的抗寒和抗旱性。这一研究结果展示了拟南芥CBF1类似基因的应用可能为冷敏植物抗寒和抗旱性的品种改良提供一条新的途径。     

过表达番茄GDP-L-半乳糖磷酸酶基因提高烟草抗MV诱导的氧化胁迫能力

为了探讨番茄GDP—L-半乳糖磷酸酶对烟草抗坏血酸（AsA）含量及抗氧化能力的影响,从番茄叶片中分离了GDP-L-半乳糖磷酸酶基因（LeGGP）,并转入到烟草中。以野生型（WT）和转正义LeGGP烟草株系T1-3和T1-15为试材,测定了甲基紫精（MV）处理下AsA、脱氢抗坏血酸（DHA）、H2O2、O2-和叶绿素含量、抗坏血酸过氧化物酶（APX）活性、光合速率和叶绿素荧光参数等。Northem杂交分析表明LeGGP的表达受MV的诱导,在MV处理下,野生型烟草的离体叶圆片发生比转基因烟草更严重的光漂白,转基因烟草的AsA含量及清除H2O2和O2-的能力明显强于野生型,过表达LePGG胀高了烟草的生长量。并且转基因烟草比野生型具有更高的净光合效率（Pn）和光系统Ⅱ（PSII）最大光化学效率（眠）。结果表明,LeGGP的过表达有助于提高烟草AsA含量及抗氧化胁迫能力。     

Overexpression of Rat Neurons Nitric Oxide Synthase in Rice Enhances Drought and Salt Tolerance

Nitric oxide (NO) has been shown to play an important role in the plant response to biotic and abiotic stresses in Arabidopsis mutants with lower or higher levels of endogenous NO. The exogenous application of NO donors or scavengers has also suggested an important role for NO in plant defense against environmental stress. In this study, rice plants under drought and high salinity conditions showed increased nitric oxide synthase (NOS) activity and NO levels. Overexpression of rat neuronal NO synthase (nNOS) in rice increased both NOS activity and NO accumulation, resulting in improved tolerance of the transgenic plants to both drought and salt stresses. nNOS-overexpressing plants exhibited stronger water-holding capability, higher proline accumulation, less lipid peroxidation and reduced electrolyte leakage under drought and salt conditions than wild rice. Moreover, nNOS-overexpressing plants accumulated less H₂O₂, due to the observed up-regulation of OsCATA, OsCATB and OsPOX1. In agreement, the activities of CAT and POX were higher in transgenic rice than wild type. Additionally, the expression of six tested stress-responsive genes including OsDREB2A, OsDREB2B, OsSNAC1, OsSNAC2, OsLEA3 and OsRD29A, in nNOS-overexpressing plants was higher than that in the wild type under drought and high salinity conditions. Taken together, our results suggest that nNOS overexpression suppresses the stress-enhanced electrolyte leakage, lipid peroxidation and H₂O₂ accumulation, and promotes proline accumulation and the expression of stress-responsive genes under stress conditions, thereby promoting increased tolerance to drought and salt stresses.     

Overexpression of LmgshF from Listeria monocytogenes in Indica Rice Confers Salt Stress Tolerance

Russian Journal of Plant Physiology - Glutathione (γ-glutamylcysteinylglycine; GSH), is a multi-functional tri-peptide antioxidant, a key agent in defense against abiotic and biotic stress. A...     

榆钱菠菜脯氨酸转运蛋白基因的克隆及转基因拟南芥的耐盐性

脯氨酸是自然界中分布最广泛 ,作用最重要的渗透保护剂之一 ,同时又是高等植物中一类重要的碳源和氮源物质。为了解环境胁迫下脯氨酸的转运调节 ,从一个典型的盐生植物榆钱菠菜 (AtriplexhortensisL .)中通过cDNA文库筛选和 5′_RACE的方法获得了一个全长的cDNA (AhProT1) ,其编码蛋白与脯氨酸转运蛋白有 6 0 %～ 6 9%的同源性 ,含有 11个跨膜结构域。聚类分析表明 ,微生物和高等植物的脯氨酸转运蛋白同源程度相对高于哺乳动物。为进一步分析脯氨酸转运蛋白在植物中的功能 ,将AhProT1置于 35S启动子下转入拟南芥 (Arabidopsisthaliana)。通过同位素示踪法发现 ,与对照植物相比 ,转基因植物在根中积累更多的脯氨酸 ;在一系列不同浓度的盐胁迫试验中 ,转基因植株最高可耐受 2 0 0mmol/LNaCl,并可持续生长 ,而对照植株在 15 0mmol/LNaCl下即已死亡。     

榆钱菠菜脯氨酸转运蛋白基因的克隆及转基因拟南芥的耐盐性

脯氨酸是自然界中分布最广泛,作用最重要的渗透保护剂之一,同时又是高等植物中一类重要的碳源和氮源物质.为了解环境胁迫下脯氨酸的转运调节,从一个典型的盐生植物榆钱菠菜( Atriplex hortensis L.)中通过cDNA文库筛选和5′-RACE的方法获得了一个全长的cDNA (AhProT1),其编码蛋白与脯氨酸转运蛋白有60%～69%的同源性,含有11个跨膜结构域.聚类分析表明,微生物和高等植物的脯氨酸转运蛋白同源程度相对高于哺乳动物.为进一步分析脯氨酸转运蛋白在植物中的功能,将AhProT1置于35S启动子下转入拟南芥(Arabidopsis thaliana).通过同位素示踪法发现, 与对照植物相比, 转基因植物在根中积累更多的脯氨酸;在一系列不同浓度的盐胁迫试验中,转基因植株最高可耐受200 mmol/L NaCl,并可持续生长,而对照植株在150 mmol/L NaCl下即已死亡.     

SpAHA1 and SpSOS1 Coordinate in Transgenic Yeast to Improve Salt Tolerance

In plant cells, the plasma membrane Na⁺/H⁺ antiporter SOS1 (salt overly sensitive 1) mediates Na⁺ extrusion using the proton gradient generated by plasma membrane H⁺-ATPases, and these two proteins are key plant halotolerance factors. In the present study, two genes from Sesuvium portulacastrum, encoding plasma membrane Na⁺/H⁺ antiporter (SpSOS1) and H⁺-ATPase (SpAHA1), were cloned. Localization of each protein was studied in tobacco cells, and their functions were analyzed in yeast cells. Both SpSOS1 and SpAHA1 are plasma membrane-bound proteins. Real-time polymerase chain reaction (PCR) analyses showed that SpSOS1 and SpAHA1 were induced by salinity, and their expression patterns in roots under salinity were similar. Compared with untransformed yeast cells, SpSOS1 increased the salt tolerance of transgenic yeast by decreasing the Na⁺ content. The Na⁺/H⁺ exchange activity at plasma membrane vesicles was higher in SpSOS1-transgenic yeast than in the untransformed strain. No change was observed in the salt tolerance of yeast cells expressing SpAHA1 alone; however, in yeast transformed with both SpSOS1 and SpAHA1, SpAHA1 generated an increased proton gradient that stimulated the Na⁺/H⁺ exchange activity of SpSOS1. In this scenario, more Na⁺ ions were transported out of cells, and the yeast cells co-expressing SpSOS1 and SpAHA1 grew better than the cells transformed with only SpSOS1 or SpAHA1. These findings demonstrate that the plasma membrane Na⁺/H⁺ antiporter SpSOS1 and H⁺-ATPase SpAHA1 can function in coordination. These results provide a reference for developing more salt-tolerant crops via co-transformation with the plasma membrane Na⁺/H⁺ antiporter and H⁺-ATPase.