Cloning, Stress Expression Analysis And Genetic Transformation Studies Of MiR1444a In Populus Trichacarpa

Populous is the major tree species of the Three-north Shelterbelt in our country thathas the irreplaceable role in alleviating the salinization and desertification of land,stopping water and soil from going away. In recent years, the research of breeding newvarieties in poplar resistance has attracted many researchers to pay more and moreattention on, especially, the obtaining of strong resistance palnt with genetic engineeringmeans in poplar breeding occupies an important position. MicroRNAs(miRNAs) are aclass of non-coding, endogenous, small RNAs that exist widely in eukaryotes. PlantmiRNAs involve in the response of palnt to biotic and abiotic stress via regulate theexpression of gene. miR1444a, a member of the Populous-specific miR1444family, mayplay important roles in plant response to a lot of environmental stresses. Here, we reportthe cloning of full-length MIR1444a gene from P.trichacarpa using RACE-PCRtechnology. Bioinformatic analysis showed the existence of many stressresponse-related cis-acting elements in the promoter region of MIR1444a gene.It meansthat miR1444a may involve in plant response to stress. What’s more, in this experiment,we analyses of the expression of mature miR1444a and its target genes (PtPPO3andPtPPO6) in response to Zn stress and dehydration stress in the roots, stems and leaves ofP. trichacarpa by RT-PCR. It implies the involvement of miR1444a in the response of P.trichacarpa to zinc stress. Based on this and previous studies, we propose a Cu-Znsensing model which may exist in P. trichacarpa. Another result showed that miR1444amay involve in the response of P. trichacarpa to dehydration stress. In order to confirmthese consequences, we constructed the over-expression vector of miR1444a andintroduced into stem section of P. trichacarpa by Agrobacterium tumefaciens-mediatedtransformation method. Finally, we obtained2transgenic lines, laiding the foundationfor further verifying the function of miR1444a and breeding for stress-resistance inpoplar.