The Effect Of Low Night Temperature And ABA On MiRNA And Target Genes Expression In Tomato Leaf

MicroRNA?miRNA?is a kind of non-coding RNA,with length about 22?24 nt.It binds to their target to regulator the post transcriptional level.miRNA plays an important role in plants physiological processes,such as growth and development,stress tolerance?low temperature,drought and salt stress?,and maintain genome integrity.In this paper,through the low night temperature and spraying ABA.Stomata ultrastructure was observed and ABA conten was detemined in tomato?Solanum lycopersicum?leaf in wild type RR and ABA deletion mutant?sit?.six miRNAs?miR160,miR162,miR166,miR1919,miR397 and miR6026?and its target genes were analyzed.The main results are as follows:1.Results showed that,as the night temperature?9? and 6??gradually reduced,wild type RR and ABA deletion mutant?sit?stomatal open significantly smaller than RR?15??and sit?15??in leaf.At low night temperature?6??,the RR leaf stomas started to close and sit did not showed leaf stomas close.However RR and sit ABA content significantly higher than RR?15??and sit?15??.2.As the spraying ABA concentration(20mg·L^-1,50mg·L^-1 and 80 mg·L^-1)was gradually increasing,wild type RR and ABA deletion mutant?sit?stomatal open significantly smaller than RR(0 mg·L^-1)and sit(0 mg·L^-1)in leaf.When ABA concentration was 80 mg·L^-1,the RR leaf stomas started to closure,and sit did not showed leaf stomas close.However RR and sit ABA content significantly higher than RR(0 mg·L^-1)and sit(0 mg·L^-1).The results show that,low night temperature and spraying ABA applying induced the synthesis of endogenous ABA,which led to stomatal closed then enhance the resistance of plants.3.In this study,the expression of 6 miRNAs and their target genes were investigated by quantitative real-time PCR?qRT-PCR?technology.The results showed that at night temperature?15??,the expression of all miRNAs decreased in sit plants compared to those of the RR plants treatment.And all their target genes up-regulated other than miR1919.All miRNAs expression in sit increased significantly after 12 h?6??.When the sit was sprayed with 80 mg·L^-1 ABA,the expressions of miR162,miR166,miR1919 and miR397 were significantly higher than that with 0 mg·L^-1?ABA?.These results suggested that miR160 and miR6026 response to ABA regulation,miR162 plays an important role in response to low night temperature stress by ABA-dependent signal pathway.