| Drought and soil salinization are important abiotic stresses affecting plant growth and survival.LEA gene is one of the genes that can be induced by drought,salt and other stress in plants.The protein encoded by this gene is a kind of protein accumulated in the late seed embryo,which has strong hydrophilicity and plays a great role in plant stress tolerance.They can protect plant cells from dehydration in drought and other adverse environmental conditions.Therefore,it is very important to study the mechanism of plant stress resistance by cloning and function analysis of the unknown LEA genes.Hammendron ammodendron is a perennial desert shrub,which is distributed in many desert and saline-alkali areas in northwest China with stronger resistance to adverse environments.At present,the molecular mechanism of H.ammodendron's adaptation to adverse environments is still unclear,and further exploration and research are needed.Therefore,in this study,the desert plant Hammendron ammodendron was used as the research material,and the full-length c DNA of HaLEA3 gene was cloned first,and performed bioinformatic analysis,expression pattern analyzed and subcellular localization.Finally,the gene was overexpressed into Arabidopsis thaliana and its effects on Arabidopsis stress resistance were analyzed.The main results are as follows:(1)The total length of HaLEA3 gene was 838 bp,ORF was 747 bp,and it encoded248 amino acids;HaLEA3 is a highly hydrophilic protein,and analysis of its domain revealed that the protein has a conserved domain of the LEA family;Amino acid sequence analysis showed that it was closely related to LEA proteins from Beta vulgaris,Chenopodium quinoa and Spinacia oleracea in the same family.(2)Tissue specific analysis showed that HaLEA3 was expressed in all tissues of Haloxylon ammodendron,and its expression was the highest in assimilating branches;under salt(350 m M NaCl)and osmotic stress(-0.75 MPa),the expression of HaLEA3was significantly up-regulated,showing that HaLEA3 was involved in the responses of Haloxylon ammodendron to drought and salt stresses.(3)The recombinant PCAMBIA1300-HaLEA3-GFP vector was constructed,and the HaLEA3 gene was transferred into tobacco by Aturobacterium-mediated transformation method for transient expression;the microscopic examination showed that HaLEA3 was localized to the plasma membrane.(4)The plate experiment showed that there was no significant difference between wild-type plants and transgenic lines overexpressing HaLEA3 under normal condition;under salt(100 m M NaCl)and osmotic(400 m M Mannitol)stresses,the transgenic lines overexpressing HaLEA3 had better growth with more stress tolerance.(5)The overexpression of HaLEA3 improved the salt tolerance of transgenic Arabidopsis thaliana.After 8 days of 250 m M NaCl treatment,the leaves of wild-type plants turned yellow gradually,while the transgenic lines grew normally.The overexpression of HaLEA3 maintained relatively stable water content,chlorophyll content and plasma membrane permeability of leaves.Shoot Na~+content of both transgenic and wild-type lines increased and K~+content decreased,but shoot Na~+content of transgenic lines was significantly lower than that of wild-type plants,and K~+content was significantly higher than that of wild-type plants;There was no significant difference in root Na~+and K~+contents between wild-type and transgenic lines.These results indicated that the expression of HaLEA3 gene can help plants maintain growth,increase plant water content,alleviate the adverse effects of drought and salt stresses,and play important roles in plant adaptation to salt and drought habitats.This study lays a foundation for clarifying the stress resistance mechanism of desert plant H.ammodendron,and can also provide additional genetic resources for the genetic improvement of crop stress resistance. |
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