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Late Embryogenesis Abundant (LEA) proteins are associated with tolerance to water-related stress. A wheat (Triticum durum) group 2 LEA proteins, known also as dehydrin (DHN-5), has been previously shown to be induced by salt and abscisic acid (ABA). In this report, we analyze the effect of ectopic expression of Dhn-5 cDNA in Arabidopsis thaliana plants and their response to salt and osmotic stress. When compared to wild type plants, the Dhn-5 transgenic plants exhibited stronger growth under high concentrations of NaCl or under water deprivation, and showed a faster recovery from mannitol treatment. Leaf area and seed germination rate decreased much more in wild type than in transgenic plants subjected to salt stress. Moreover, the water potential was more negative in transgenic than in wild type plants. In addition, the transgenic plants have higher proline contents and lower water loss rate under water stress. Also, Na+ and K+ accumulate to higher contents in the leaves of the transgenic plants. Our data strongly support the hypothesis that Dhn-5, by its protective role, contributes to an improved tolerance to salt and drought stress through osmotic adjustment.  相似文献   

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The CCCH type zinc finger proteins are a super family involved in many aspects of plant growth and development. In this study, we investigated the response of one CCCH type zinc finger protein AtZFP1 (At2g25900) to salt stress in Arabidopsis. The expression of AtZFP1 was upregulated by salt stress. Compared to transgenic strains, the germination rate, emerging rate of cotyledons and root length of wild plants were significantly lower under NaCl treatments, while the inhibitory effect was significantly severe in T-DNA insertion mutant strains. At germination stage, it was mainly osmotic stress when treated with NaCl. Relative to wild plants, overexpression strains maintained a higher K+, K+/Na+, chlorophyll and proline content, and lower Na+ and MDA content. Quantitative real-time PCR analysis revealed that the expression of stress related marker genes KIN1, RD29B and RD22 increased more significantly in transgenic strains by salt stress. Overexpression of AtZFP1 also enhanced oxidative and osmotic stress tolerance which was determined by measuring the expression of a set of antioxidant genes, osmotic stress genes and ion transport protein genes such as SOS1, AtP5CS1 and AtGSTU5. Overall, our results suggest that overexpression of AtZFP1 enhanced salt tolerance by maintaining ionic balance and limiting oxidative and osmotic stress.  相似文献   

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Despite the increasing understanding of the stress‐responsive roles of zinc‐finger RNA‐binding proteins (RZs) in several plant species, such as Arabidopsis thaliana, wheat (Triticum aestivum) and rice (Oryza sativa), the functions of RZs in cabbage (Brassica rapa) have not yet been elucidated. In this study, the functional roles of the three RZ family members present in the cabbage genome, designated as BrRZ1, BrRZ2 and BrRZ3, were investigated in transgenic Arabidopsis under normal and environmental stress conditions. Subcellular localization analysis revealed that all BrRZ proteins were exclusively localized in the nucleus. The expression levels of each BrRZ were markedly increased by cold, drought or salt stress and by abscisic acid (ABA) treatment. Expression of BrRZ3 in Arabidopsis retarded seed germination and stem growth and reduced seed yield of Arabidopsis plants under normal growth conditions. Germination of BrRZ2‐ or BrRZ3‐expressing Arabidopsis seeds was delayed compared with that of wild‐type seeds under dehydration or salt stress conditions and cold stress conditions, respectively. Seedling growth of BrRZ3‐expressing transgenic Arabidopsis plants was significantly inhibited under salt, dehydration or cold stress conditions. Notably, seedling growth of all three BrRZ‐expressing transgenic Arabidopsis plants was inhibited upon ABA treatment. Importantly, all BrRZs possessed RNA chaperone activity. Taken together, these results indicate that the three cabbage BrRZs harboring RNA chaperone activity play diverse roles in seed germination and seedling growth of plants under abiotic stress conditions as well as in the presence of ABA.  相似文献   

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Abiotic stresses such as salinity and drought have adverse effects on plants. In the present study, a Na+/H+ antiporter gene homologue (LfNHX1) has been cloned from a local halophyte grass (Leptochloa fusca). The LfNHX1 cDNA contains an open reading frame of 1,623 bp that encodes a polypeptide chain of 540 amino acid residues. LfNHX1 protein sequence showed high similarity with NHX1 homologs reported from other halophyte plants. Amino acid and nucleotide sequence similarity, protein topology modeling and the presence of conserved functional domains in the LfNHX1 protein sequence classified it as a vacuolar NHX1 homolog. The overexpression of LfNHX1 gene under CaMV35S promoter conferred salt and drought tolerance in tobacco plants. Under drought stress, transgenic plants showed higher relative water contents, photosynthetic rate, stomatal conductance and membrane stability index as compared to wild type plants. More negative value of leaf osmotic potential was also observed in transgenic plants when compared with wild type control plants. Transgenic plants showed better germination and root growth at 2 mg L?1 Basta herbicide and three levels (100, 200 and 250 mM) of sodium chloride. These results showed that LfNHX1 is a potential candidate gene for enhancing drought and salt tolerance in crops.  相似文献   

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New multiple-stress related gene isolated from sweet potato and designated it as MusI (multiple stress responsible gene I). Sequence analysis revealed that its full length cDNA was 998 bp long and included a 717 bp open reading frame encoding for 238 amino acids. Comparison of its cDNA and genomic DNA sequence showed that 3 exons were divided by 2 introns in its ORF region. Its deduced amino acid sequence contained a conserved rubber elongation factor (REF) domain and showed high homology with many stress-related proteins. Therefore, it was named MuSI (multiple stress responsible gene I). Southern hybridization analysis indicated that the MuSI gene may belong to a multi-gene family. Expression pattern of the MuSI gene showed that it was differently expressed among roots, stems, leaves, and flowers of a sweet potato, and its expression level was especially high in flowers and white fibrous roots. Its expression was also highly induced by various stress signals including dehydration, high salt, heavy metal, oxidation, and plant hormones. Stress tolerance experiment using transgenic plants overexpressing the MuSI gene showed that all independent transgenic tobacco lines have enhanced tolerance to high temperature stress. Among them, transgenic line 6 particularly showed tolerance to salt, heavy metal, and osmotic stress as well. These results suggest that the MuSI gene functions as a positive regulator of various stress responses and may be useful in improving stress tolerance of transgenic plants.  相似文献   

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Iron-sulfur cluster biosynthesis involving the nitrogen fixation (Nif) proteins has been proposed as a general mechanism acting in various organisms. NifU-like protein may play an important role in protecting plants against abiotic and biotic stresses. An iron-sulfur cluster scaffold protein gene, IbNFU1, was isolated from a salt-tolerant sweetpotato (Ipomoea batatas (L.) Lam.) line LM79 in our previous study, but its role in sweetpotato stress tolerance was not investigated. In the present study, the IbNFU1 gene was introduced into a salt-sensitive sweetpotato cv. Lizixiang to characterize its function in salt tolerance. The IbNFU1-overexpressing sweetpotato plants exhibited significantly higher salt tolerance compared with the wild-type. Proline and reduced ascorbate content were significantly increased, whereas malonaldehyde (MDA) content was significantly decreased in the transgenic plants. The activities of superoxide dismutase (SOD) and photosynthesis were significantly enhanced in the transgenic plants. H2O2 was also found to be significantly less accumulated in the transgenic plants than in the wild-type. Overexpression of IbNFU1 up-regulated pyrroline-5-carboxylate synthase (P5CS) and pyrroline-5-carboxylate reductase (P5CR) genes under salt stress. The systemic up-regulation of reactive oxygen species (ROS) scavenging genes was found in the transgenic plants under salt stress. These findings suggest that IbNFU1gene is involved in sweetpotato salt tolerance and enhances salt tolerance of the transgenic sweetpotato plants by regulating osmotic balance, protecting membrane integrity and photosynthesis and activating ROS scavenging system.  相似文献   

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