Overexpression of Medicago sativa cv. Pianguan miR397-5p gene enhances drought tolerance in K326 tobacco

Background: Alfalfa ( Medicago sativa cv. Piangu an) is one of the most widely cultivated perennial leguminous forage. Drought is one of the major abiotic factors that affect alfalfa productivity. MicroRNAs (miRNAs) have been proved playing important roles in plant growth, development and stress response. Results In this study, High-throughput sequencing (HTSeq) was used to identify the miRNAs and their target related to drought stress from polyethylene glycol treated and control alfalfa samples, differential expression analysis showed that a large number of miRNAs were down-regulated or up-regulated as a result of PEG-6000 stress. qRT-PCR and sequencing analysis results showed that the relative expression of 9 miRNAs and their target genes related to drought stress, 3 miRNAs were considered potential drought-responsive miRNAs, including miR159b, miR397-5p and unconservative_6_4438. The recombinant plasmid vector pBWA(V)KS-miR397 was constructed and introduced into tobacco successfully. 31 positive seedlings were obtained through the process of infection, co-culture, differentiation and rooting. The physiologieal variation of transgenic tobacco under drought stress was researched. Finally, a new tobacco variety with high drought resistance was obtained. Conclusion These finding although need further studies to confirm, these data provide a useful evidence for the possible involvement of miRNAs in the process of drought response in the alfalfa plant which could help explain the drought stress responses and to alleviate the adverse effects of drought stress on plant growth and development.