Excavation And Functional Verification Of Medicago Sativa Cv. Pianguan MiRNAs Involved Drought-resistant

About one-third of the world's regions are arid and semi-arid,unexpectedly,arid climates are also common in other terrestrial areas,while the water shortages can cause damage to plants,enormous social problems and economic losses.Medicago Sativa cv.pianguan is drought tolerant,resistant to barren and conservation of both moisture and soil.It can grow well under abominable environmental conditions.Micro RNAs(mi RNAs)play a key role in plant growth,development and resistance when plants are subjected to drought stress in the external environment.In the study,we identify the genes expression from control and drought-treated alfalfa samples by high-throughput RNA-sequencing technology,identified differentially expressed mi RNAs,predicted their target genes.According to the GO and KEGG databases,screened drought-related mi RNAs.And according to the results,the mi R397-pre of Medicago Sativa cv.pianguan was transformed into tobacco by agrobacterium transformation technology,and the functional verification of transformation tobacco was carried out.The main findings of this test are as follows:1.High-throughput sequencing of Medicago Sativa cv.pianguan,we identified 729 mi RNAs,of which 599 are known,130 are newly predicted mi RNAs.704 target genes were predicted using bioinformatics methods.GO and KEGG databases analysis indicated that a large number of mi RNAs and their target genes were involved in plant reactive oxygen species(ROS)scavenging system,signal transduction pathway,production and metabolism of plant hormone,and proposed a schematic diagram of the regulation network under drought stress.2.The plant vector of p BWA(V)KS-mi R397-pre was constructed successfully,and was transformed into tobacco by the mediation of agrobacterium.The net photosynthetic rate of transformation tobacco was significantly lower than the non-transformation tobacco.It was analyzed that the decrease of net photosynthetic rate was caused by non-stomatal factors,and the light curve of transformation tobacco was lower than the non-transformation tobacco,indicating that the photosynthetic capacity of transformation tobacco was inferior.The photosynthetic electron transfer of the transformation tobacco is inhibited,and the PSII light energy conversion efficiency is lowered.We measured malondialdehyde,superoxide dismutase,proline,leaf water content and chlorophyll content in transformation and nontransformation tobacco.The result showed that the mi R397 of Medicago Sativa cv.pianguan was involved in osmotic regulation and active oxygen scavenging systems,etc.,increase the sensitivity of tobacco to drought.