Characterization of AhLea-3 and its enhancement of salt tolerance in transgenic peanut plants

BACKGROUND: Late embryogenesis abundant (LEA) proteins were reported to be related to adversity stress and drought tolerance. Lea-3 from Arachis hypogaea L. (AhLea-3) was previously found to be related to salt tolerance according to the result of transcriptome profiling and digital gene expression analysis. So, AhLea-3 was cloned and the salt tolerance was validated by transgenic peanut plants. RESULTS: AhLea-3 was isolated from M34, a salt-resistant mutant of peanut, with its cDNA as the template. AhLea-3 contains one intron and two extrons, and the full-length cDNA sequence contains 303 bp. AhLea3 was ligated to pCAMBIA1301 to obtain the overexpression vector pCAMBIA1301-AhLea-3, which was then transferred into peanut variety Huayu23. The expression level of AhLea-3, as determined by qRTPCR analysis, was >10 times higher in transgenic than in non-transgenic plants. Five days after they were irrigated with 250 mM NaCl, the transgenic plants showed less severe leaf wilting, higher activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase), and lower malonic dialdehyde content than non-transgenic plants. Relative to non-transgenic plants, the transgenic plants had a higher photosynthetic net rate, stomatal conductance, and transpiration rate, and a lower intercellular CO2 concentration after salt stress treatment (250 mM NaCl). CONCLUSIONS: These results indicate that overexpression of AhLea-3 increased the salt tolerance of transgenic peanut plants. AhLea-3 might become a useful gene resource for the variety breeding of salinity tolerance in peanut.

Cloning,expression and function analysis of DOLEA2 gene from Dendrobium officinale / 药学学报

LEA (late embryogenesis abundant) proteins that are highly hydrophilic and thermally stable play a role in plant defense. The full-length cDNA of DoLEA2 was cloned by rapid amplification of cDNA ends (RACE) from Dendrobium officinale (GenBank number:KY626329). The cDNA is 1 224 bp and encodes 313 amino acids. The deduced DoLEA2 protein contained LEA_2 and WHy domains. Multiple sequence alignment revealed that DoLEA2 shared a high homology with other species. Phylogenetic tree showed that DoLEA2 belonged to the monocotyledon and its closest relative was P. aphrodite. DoLEA2 was differentially expressed in the different organ. The expression was most abundant in the leaves, followed by that of the roots and stem. DoLEA2 could express in Escherichia coli BL21 (DE3), and the best induction conditions were 0.5 mmol·L-1 IPTG at 37℃ for 4 h. The growth curves of E. coli BL21 (DE3) showed that the recombinant DoLEA2 protein improved tolerate against salt stress over the control. This study represents the first time of cloning and identification of the function of LEA2 in D. officinale. The result sets up an important foundation for the molecular mechanism of stress resistance in Dendrobium officinale.

Molecular cloning and expression analysis of the MaASR1 gene in banana and functional characterization under salt stress

Background Abscisic acid (ABA)-, stress- and ripening-induced protein (ASR) is plant-specific hydrophilic transcriptional regulators involved in sucrose stress and wounding in banana. However, it is not known whether banana ASR genes confer salt stress tolerance. The contexts of the study was to analysis the sequence characterization of banana ASR1, and identify its expression patterns and function under salt stress using quantitative real-time PCR (qPCR) and overexpression in Arabidopsis. The purpose was to evaluate the role of banana ASR1 to salt stress tolerance employed by plants. Results A full-length cDNA isolated from banana fruit was named MaASR1, and it had a 432 bp open reading frame (ORF) encoding 143 amino acids. MaASR1 was preferential expression in roots and leaves compared to low expression in fruits, rhizomes and flowers. Under salt stress, the expression of MaASR1 quickly increased and highest expression level was detected in roots and leaves at 4 h, and then gradually decreased. These results suggested that MaASR1 expression was induced under salt stress. MaASR1 protein was localized in the nucleus and plasma membrane. MaASR1 was transformed to Arabidopsis and verified by southern and northern analysis, transgenic lines L14 and L38 integrated one and two copies of MaASR1, respectively, while overexpression in transgenic lines provided evidence for the role of MaASR1 to salt stress tolerance. Conclusions This study demonstrated that overexpression of MaASR1 in Arabidopsis confers salt stress tolerance by reducing the expression of ABA/stress-responsive genes, but does not affect the expression of the ABA-independent pathway and biosynthesis pathway genes.

Effect of two kinds of endophytic fungi on salt resistance of Chrysanthemum morifolium / 中草药

Objective: The NaCl stress conditions were simulated to study the effect of the endophytic fungi C1, C4 on antisalty characteristic of Chrysanthemum morifolium in the adverse circumstance. Methods: Endophytic Botrytis sp. (C1) and Chaetomium globosum (C4) were inoculated to the C. morifolium plantlets which were planted in the pots in order to research the effects of salt stress on physiological indicators of C. morifolium. Results: With the increase of NaCl concentration, the water content of root and leaf decreased in every group. The loss of root and leaf's water in fungi-treated group was smaller than that in the control group. SOD activities in every group increased with the increase of NaCl concentration, and achieved the peak value at 20 g/L NaCl. The SOD activity in fungi-treated group was higher than that in the control group. Soluble protein of fungi-treated group was higher than that in the control group, and C4 group surpassed C1 group. POD activity increased firstly and then decreased, and compared to the control group, the POD activities in C4 and C1 groups increased by 25.50% and 1.35%, respectively at 15 g/L NaCl. PAL activity of C4 treated group was seven folds compared to the control group at 15 g/L NaCl. Conclusion: Endophytic fungi could enhance the salt-tolerant ability of C. morifolium, and the effect in C4 group was better than C1 group.