Cloning of a 4CL gene fragment and construction of a RNAi expression vector of Pennisetum purpureum Construction of RNA interference vector carrying two genes of DS and CAS of Betula platyphylla Suk(Birch.) Construction of ihpRNA Expression Vector of MhVPE Gene from Malus hupehensis and Verification by Transgenic Arabidopsis thaliana Construction of ihpRNA Expression Vector of MhVPE Gene from Malus hupehensis and Verification by Transgenic Arabidopsis thaliana RNAi Vector Construction of AtDof1.7 Transcription Factors and Genetic Transformation into Arabidopsis thaliana Construction of ihpRNA Expression Vectorof MsLEA3-1 Gene from Medicago sativa L. and Genetic Transformation in Tobacco