Heterologous expression of the AtDREB1A gene in chrysanthemum increases drought and salt stress tolerance

DNA cassette containing an AtDREB1A cDNA and a nos terminator, driven by a cauliflower mosaic 35S promoter, or a stress-inducible rd29A promoter, was transformed into the ground cover chrysanthemum (Dendranthema grandiflorum) ‘Fall Color’ genome. Compared with wild type plants, severe growth retardation was observed in 35S:DREB1A plants, but not in rd29A:DREB1A plants. RT-PCR analysis revealed that, under stress conditions, the DREB1A gene was over-expressed constitutively in 35S:DREB1A plants, but was over-expressed inductively in rd29A:DREB1A plants. The transgenic plants exhibited tolerance to drought and salt stress, and the tolerance was significantly stronger in rd29A:DREB1A plants than in 35S:DREB1A plants. Proline content and SOD activity were increased inductively in rd29A:DREB1A plants than in 35S:DREB1A plants under stress conditions. These results indicate that heterologous AtDREB1A can confer drought and salt tolerance in transgenic chrysanthemum, and improvement of the stress tolerance may be related to enhancement of proline content and SOD activity.     

Heterologous expression of the AtDREB1A gene in chrysanthemum increases drought and salt stress tolerance

DNA cassette containing an AtDREB1A cDNA and a nos terminator, driven by a cauliflower mosaic 35S promoter, or a stress-inducible rd29A promoter, was transformed into the ground cover chrysanthemum (Dendranthema grandiflorum) ‘Fall Color’ genome. Compared with wild type plants, severe growth retardation was observed in 35S:DREB1A plants, but not in rd29A:DREB1A plants. RT-PCR analysis revealed that, under stress conditions, the DREB1A gene was over-expressed constitutively in 35S:DREB1A plants, but was over-expressed inductively in rd29A:DREB1A plants. The transgenic plants exhibited tolerance to drought and salt stress, and the tolerance was significantly stronger in rd29A:DREB1A plants than in 35S:DREB1A plants. Proline content and SOD activity were increased inductively in rd29A:DREB1A plants than in 35S:DREB1A plants under stress conditions. These results indicate that heterologous AtDREB1A can confer drought and salt tolerance in transgenic chrysanthemum, and improvement of the stress tolerance may be related to enhancement of proline content and SOD activity.     

多胺与环境胁迫关系研究进展

多胺是植物对胁迫响应的重要物质,可以抵消胁迫引起的负效应.多胺预处理可缓解胁迫引起的伤害,通过转基因技术过量表达多胺可提高植物胁迫耐性.本文综述了生物胁迫和非生物胁迫条件下,多胺的合成、代谢、功能及其作为抗氧化剂减少胁迫诱导氧化损伤的研究现状.重点综述了病虫胁迫、盐胁迫、重金属胁迫、渗透胁迫,也简要的综述了其它胁迫如低氧胁迫、冷胁迫、酸胁迫、辐射胁迫等条件下植物体内多胺合成的变化及功能.     

A Putative Plasma Membrane Cation/proton Antiporter from Soybean Confers Salt Tolerance in <Emphasis Type="Italic">Arabidopsis</Emphasis>

Cation transport is thought to be an important process for ion homeostasis in plant cells. Here, we report that a soybean putative cation/proton antiporter GmCAX1 may be a mediator of this process. GmCAX1 is expressed in all tissues of the soybean plants but at a lower level in roots. Its expression was induced by PEG, ABA, Ca²⁺, Na⁺ and Li⁺ treatments. The GmCAX1-GFP fusion protein was mainly localized in plasma membrane of the transgenic Arabidopsis plant cells and onion epidermal cells. Transgenic Arabidopsis plants overexpressing GmCAX1 accumulated less Na⁺, K⁺, and Li⁺, and were more tolerant to elevated Li⁺ and Na⁺ levels during germination when compared with the controls. These results suggest that GmCAX1 may function as an antiporter for Na⁺, K⁺ and Li⁺. Modulation of this antiporter may be beneficial for regulation of ion homeostasis and thus plant salt tolerance.     

Germination profiling of lentil genotypes subjected to salinity stress

• Salinity is one of the most severe environmental stresses, negatively affecting productivity of salt‐sensitive crop species. Given that germination is the most critical phase in the plant life cycle, the present study aimed to determine seed germination potential and associated traits under salt stress conditions as a simple approach to identify salt‐tolerant lentil genotypes.
• The genetic material consisted of six lentil genotypes whose adaptation to various agroclimatic conditions is not well elucidated. Salinity stress was applied by addition of NaCl at three different levels of stress, while non‐stressed plants were included as controls. Evaluation of tolerance was performed on the basis of germination percentage, seed water absorbance, root and shoot length, seedling water content, seedling vigour index and number of seedlings with an abnormal phenotype.
• Overall, our findings revealed that salinity stress substantially affects all traits associated with germination and early seedling growth, with the effect of salinity being dependent on the level of stress applied. It is noteworthy, however, that genotypes responded differently to the varying salinity levels. In this context, Samos proved the most salt‐tolerant genotype, indicating its possible use for cultivation under stress conditions.
• In conclusion, the determination of seed germination and early growth potential may be exploited as an efficient strategy to reveal genetic variation in lentil germplasm of unknown tolerance to salinity stress. This approach allows selection of desirable genotypes at early growth stages, thus enabling more efficient application of various breeding methods to achieve stress‐tolerant lentil genotypes.

     

谷胱甘肽在植物抗逆中的作用

在简要总结谷胱甘肽(GSH)的结构、分布、代谢和调控的基础上,概述了GSH在植物抗逆性方面的 作用,认为GSH通过植物体内螯合肽合成酶催化下聚合形成植物螯合肽来抵抗重金属的胁迫,作为抗氧化剂 参与低温伤害的保护,以亲核进攻一结合反应方式进行生物解毒等。讨论了GSH在植物抗逆性功能中的机 制,并就GSH今后在该方面的研究前景进行了展望。     

Plant salt-tolerance mechanism: A review

Almost all crops that are important to humans are sensitive to high salt concentration in the soil. The presence of salt in soil is one of the most significant abiotic stresses in farming. Therefore, improving plant salt tolerance and increasing the yield and quality of crops in salty land is vital. Transgenic technology is a fast and effective method to obtain salt-tolerant varieties. At present, many scholars have studied salt damage to plant and plant salt-tolerance mechanism. These scholars have cloned a number of salt-related genes and achieved high salt tolerance for transgenic plants, thereby showing attractive prospects.In this paper, the salt-tolerance mechanism of plants is described from four aspects: plant osmotic stress, ion toxicity, oxidative stress, and salt tolerance genes. This review may help in studies to reveal the mechanism of plant salt tolerance, screen high efficiency and quality salt tolerance crops.     

植物逆境胁迫抗性的功能基因组研究策略

植物对逆境胁迫抗性的功能基因组研究主要是寻找胁迫抗性位点在相关物种基因组中的保守位置,发现胁迫反应中的高度保守序列,确定植物胁迫反应的调控机理,进而得到植物对逆境胁迫抗性的关键代谢途径和其中的关键调控因子,为进一步选择用于改良植物对逆境胁迫抗性的关键基因奠定基础。本文从主要模式植物(苔藓类植物、复苏植物、盐土植物和甜土植物)、主要技术策略(基因的差异表达分析、基因表达序列标签、cDNA芯片技术。基因表达序列分析和基因敲除和突变体筛选分析)和生物信息学方法(数据分析的生物信息学方法设计到序列比较、比较基因组学、电子克隆)等三个方面对国内外植物逆境胁迫抗性的功能基因组研究策略作了全面综述。     

AtsHsp17.6-CⅠ和AtsHsp17.6-CⅡ基因对非生物胁迫的应答研究

小分子热激蛋白是植物受到热胁迫后的主要表达产物之一,与植物细胞耐热有密切关系。该研究发现,拟南芥小分子热激蛋白基因AtsHsp17.6-CⅠ和AtsHsp17.6-CⅡ 除热激之外,重金属离子Ni⁺、Pb²⁺、Cu²⁺、Zn²⁺和Al³⁺均能诱导这2个热激蛋白基因的表达;氧化胁迫和渗透胁迫同样也能诱导它们表达。该研究将由CaMV35S启动子驱动的这2个小分子热激蛋白基因导入拟南芥,RT-PCR分析表明,2个小分子热激蛋白基因在转基因植物中呈现组成型表达。实验结果表明,组成型表达小分子热激蛋白基因AtsHsp17.6-CⅠ的转基因植物表现出对6 μmol·L^-1 Cd²⁺胁迫、0.4% NaCl胁迫的耐受性。研究表明,这2个小分子热激蛋白基因可能参与着多种抗逆途径,推测其能够减轻或抵抗逆境胁迫引起的伤害并对其进行修复。     

三种冬青属树种的耐涝性和耐旱性评价

通过致死性干旱和致死性水涝处理,用生理生态方法,对冬青(Ilexchinensis)、绿冬青(I.viridis)和无刺枸骨(I.cornatavar.fortunei)进行抗逆性研究。耐涝性结果表明随淹水时间延长,3种受淹冬青体内的游离脯氨酸和丙二醛含量增加,净光合速率下降;比较而言,绿冬青上述受淹反应出现早,无刺枸骨出现迟,而冬青介于二者之间;绿冬青耐涝约1周,无刺枸骨耐涝2周以上,冬青耐涝介于二者之间,在江南水乡推广利用,耐涝方面不会成为限制因素。耐旱结果表明随干旱的逐渐加重,3种冬青体内的游离脯氨酸含量呈上升趋势,比较而言,绿冬青上升的峰值出现早,冬青和无刺枸骨的上升峰值出现迟;绿冬青耐旱约15d,无刺枸骨耐旱约25d,冬青介于二者之间。3种冬青均有一定的抗逆性,其中无刺枸骨对水胁迫的适应能力最强,冬青次之,而绿冬青相对较弱。     

Study of the tolerance of Hippochaete ramosissimum to Cu stress

We investigated the tolerance of Hippochaete ramosissimum and the changes in physiological metabolism following exposure to copper using pot experiments and analyzing plant physiology and biochemistry. The results showed that Cu tolerance in Hippochaete ramosissimum varied significantly between different populations; the tolerance of plants living in Cu polluted areas for extended periods of time exceeded that of plants living in unpolluted areas. SOD and POD activities in highly Cu tolerant plants increased noticeably following exposure to Cu. This indicates that maintaining and increasing the two kinds of protective enzyme activities are the primary foundations of plant tolerance. However, no change in CAT activity was demonstrated following Cu exposure. In summary, there existed considerable differences in physiological metabolism between different populations of Hippochaete ramosissimum following exposure to Cu.     

Study of the tolerance of Hippochaete ramosissimum to Cu stress

We investigated the tolerance of Hippochaete ramosissimum and the changes in physiological metabolism following exposure to copper using pot experiments and analyzing plant physiology and biochemistry. The results showed that Cu tolerance in Hippochaete ramosissimum varied significantly between different populations; the tolerance of plants living in Cu polluted areas for extended periods of time exceeded that of plants living in unpolluted areas.SOD and POD activities in highly Cu tolerant plants increased noticeably following exposure to Cu. This indicates that maintaining and increasing the two kinds of protective enzyme activities are the primary foundations of plant tolerance. However, no change in CAT activity was demonstrated following Cu exposure. In summary, there existed considerable differences in physiological metabolism between different populations of Hippochaete ramosissimum following exposure to Cu.     

内生真菌对植物抗旱性的影响

内生真菌广泛地存在于植物体内,它们在植物体内的生活不会对植物引起任何感病症状,而且内生真菌侵染对植物生长、生物和非生物胁迫抗性很好的促进作用,理解内生真菌在提高植物干旱胁迫耐受性方面的作用和机理对其在缓解植物干旱胁迫中的应用有重要意义。这篇综述介绍了植物内生真菌的多样性、对植物抗旱性的影响及其作用机理等方面的研究进展。内生真菌对植物抗旱性提高的机理包括:干旱耐受、干旱回避和干旱恢复。文中还对以后的研究进行了展望。     

Glycinebetaine accumulation is more effective in chloroplasts than in the cytosol for protecting transgenic tomato plants against abiotic stress

Tomato (Lycopersicon esculentum Mill. cv. Moneymaker) plants were transformed with a gene for choline oxidase (codA) from Arthrobacter globiformis. The gene product (CODA) was targeted to the chloroplasts (Chl-codA), cytosol (Cyt-codA) or both compartments simultaneously (ChlCyt-codA). These three transgenic plant types accumulated different amounts and proportions of glycinebetaine (GB) in their chloroplasts and cytosol. Targeting CODA to either the cytosol or both compartments simultaneously increased total GB content by five- to sixfold over that measured from the chloroplast targeted lines. Accumulation of GB in codA transgenic plants was tissue dependent, with the highest levels being recorded in reproductive organs. Despite accumulating, the lowest amounts of GB, Chl-codA plants exhibited equal or higher degrees of enhanced tolerance to various abiotic stresses. This suggests that chloroplastic GB is more effective than cytosolic GB in protecting plant cells against chilling, high salt and oxidative stresses. Chloroplastic GB levels were positively correlated with the degree of oxidative stress tolerance conferred, whereas cytosolic GB showed no such a correlation. Thus, an increase in total GB content does not necessarily lead to enhanced stress tolerance, but additional accumulation of chloroplastic GB is likely to further raise the level of stress tolerance beyond what we have observed.     

Genotype differences in the metabolism of proline and polyamines under moderate drought in tomato plants

Water stress is one of the most important factors limiting the growth and productivity of crops. The implication of compatible osmolytes such as proline and polyamines in osmotic adjustment has been widely described in numerous plants species under stress conditions. In the present study, we investigated the response of five cherry tomato cultivars (Solanum lycopersicum L.) subjected to moderate water stress in order to shed light on the involvement of proline and polyamine metabolism in the mechanisms of tolerance to moderate water stress. Our results indicate that the most water stress‐resistant cultivar (Zarina) had increased degradation of proline associated with increased polyamine synthesis, with a higher concentration of spermidine and spermine under stress conditions. In contrast, Josefina, the cultivar most sensitive to water stress, showed a proline accumulation associated with increased synthesis after being subjected to stress. In turn, in this cultivar, no rise in polyamine synthesis was detected. Therefore, all the data appear to indicate that polyamine metabolism is more involved in the tolerance response to moderate water stress.     

A lea-class gene of tomato confers salt and freezing tolerance when expressed in Saccharomyces cerevisiae

During periods of water deficit, plants accumulate late embryogenesis-abundant (LEA) proteins which are thought to protect cells from stresses associated with dehydration. One of these genes, le25, is expressed in tomato leaves and roots in response to water deficit and abscisic acid accumulation. To study the function of this protein and to test the effect of overproduction of the LE25 protein in Saccharomyces cerevisiae (Sc), a recombinant plasmid in which le25 is expressed under the control of the GAL1 promoter was constructed. The content of LE25 was high in Sc cells transformed with the recombinant plasmid. The transformant exhibited several stress-tolerant phenotypes. Growth of the transformant in a medium with 1.2 M NaCl was improved, as compared to a control strain. While the control strain showed a long lag phase of 40 h, le25-expressing cells showed a shortened lag phase of 10 h. However, no growth improvement was observed in a medium with 2 M sorbitol. In addition, the transformant had an increased survival rate after freezing stress, but not after high-temperature stress. These results, together with its predicted secondary structure, may indicate that LE25 functions as an ion scavenger.     

The role of glycine betaine in the protection of plants from stress: clues from transgenic plants

The acclimation of a plant to a constantly changing environment involves the accumulation of certain organic compounds of low molecular mass, known collectively as compatible solutes, in the cytoplasm. The evidence from numerous investigations of the physiology, genetics, biophysics and biochemistry of plants strongly suggests that glycine betaine (GB), an amphoteric quaternary amine, plays an important role as a compatible solute in plants under various types of environmental stress, such as high levels of salts and low temperature. Plant species vary in their capacity to synthesize GB and some plants, such as spinach and barley, accumulate relatively high levels of GB in their chloroplasts while others, such as Arabidopsis and tobacco, do not synthesize this compound. Genetic engineering has allowed the introduction into GB-deficient species of biosynthetic pathways to GB from both micro-organisms and higher plants; this approach has facilitated investigations of the importance of GB in stress protection. In this review, we summarize recent progress in the genetic manipulation of the synthesis of GB, with special emphasis on the relationship between the protective effects of GB in vivo and those documented in vitro.     

LEA蛋白与植物抗逆性

植物受到逆境胁迫后,LEA蛋白大量表达,可以减轻逆境引起的伤害。本文对LEA蛋白的种类、特性和功能,LEA蛋白基因结构及其表达调控,以及LEA基因表达和LEA蛋白积累与植物抗逆性的关系等方面的研究进展作了简要综述。