异源表达偏关苜蓿miR397-5p增强烟草干旱胁迫耐受能力OA北大核心CSTPCD

Medicago sativa cv.'Pianguan'is a well-regarded local germplasm in Shanxi Province,known for its strong stress resistance,adaptability,and resistance to barren soils.It is crucial to identify genes related to drought resistance in M.sativa cv.'Pianguan',so that they can be utilized for the genetic enhancement of alfalfa,thereby facilitating the development of new germplasm.In this study,miR397-5p was identified as a potential microRNA responsive to drought stress in M.sativa cv.'Pianguan'through miRNA sequencing analysis.The responsiveness of miR397-5p from M.sativa cv.'Pianguan'to drought stress was validated in transgenic tobacco,and its potential downstream target,and its effects,were identified.After drought stress,miR397-5p-overexpressing tobacco showed elevated levels of osmotic regulators,including soluble sugars,soluble proteins,and proline.Additionally,the activities of the antioxidant enzymes catalase,superoxide dismutase,and peroxidase were increased,while the malondialdehyde content was decreased.Under drought stress,miR397-5p decreased the expression of its target gene LAC4.In miR397-5p-overexpressing tobacco,most genes encoding key enzymes in the lignin biosynthesis pathway(PAL,4CL,CCR,CAD,HCT,F5H,and PAO)showed decreased transcript levels,while genes such as C4H,CCoAOMT,COMT,and others exhibited increased transcript levels.Additionally,the lignin content was decreased in miR397-5p-overexpressing tobacco.The transcript levels of most of these genes and lignin content exhibited consistent trends.It was inferred that M.sativa cv.'Pianguan'may regulate lignin accumulation in response to drought stress through miR397-5p-LAC4,but the specific underlying mechanism needs to be further investigated.Further research is required to clarify the mechanism of this response.The results of this study may provide a genetic resource for the genetic improvement of alfalfa,which is potentially valuable for the creation of excellent new germplasm.