Function Identification And Mechanism Analysis Of Poncirus Trifoliata Ptr-miR04 In Cold Tolerance

MicroRNA(miRNA),a kind of endogenous conservative non-coding small molecule RNA,widely exists in animals and plants and is involved in various stages of growth and development in plants.However,there are not so many studies on low-temperature related miRNAs in citrus.Based on the previous studies,function of a new microRNA(ptr-miR04)from Poncirus trifoliata in cold resistance is analysed.The main results are as follows:1.It is found that the cold-resistant performance of T2 pre-miR04 transgenic tobacco was lower than that of wild type,and this result was confirmed by physiological indexes such as histological staining and electrolyte leakage.2.Tre pre-miR04 over expression vector was transformed into lemon to obtain some positive plants.Overexpression of pre-miR04 decreased the cold resistance of the transgenic plants,which was verified by measurement of related physiological indexes.In addition,ptr-miR04 interference vector was constructed using STTM technology and transformed into Poncirus trifoliata.3.One of the target genes of the ptr-miR04 is Cs8g08710 encoding fructosebisphosphate aldolase(FBA).Relative expression of pre-miR04 and Cs8g08710 were inversely under low temperature in Poncirus trifoliata.Transient expression experiment revealed that the fluorescence signal of tobacco leaves co-expressing by ptr-miR04 and FBA was reduced.4.The total soluble sugar contents in transgenic plants were higher than those in wildtype plants before low-temperature treatment,may be due to influence of the glucose metabolism in transgenic plants.In summary,ptr-miR04 is a negative regulator in response to low temperatures,which may be attributed to its regulation on FBA.