Characterization Of Serrate Gene In Apple (Malus × Domestica) In Response To Drought

Apple(Malus × domestica)is one of the most important fruit in the world.Located to the northwest of China,the loess plateau region is one of the best place for apple production.However,the rainfall in loess plateau is limited,which affects the development of apple industry seriously.Therefore,identification of drought responsive genes in apple and study of their functions have significant meanings for breeding new apple varieties with high quality and drought resistance.In this paper,we identified and cloned MdSE(SERRATE)gene in ‘Golden Delicious '(Malus × domestica Borkh.cv.Golden Delicious),then obtained RNA interference(RNAi)and overexpression transgenic apple lines by transgenic method.Then we tested the phonotype of transgenic plants under drought.Furthermore,we verified the function of MdSE in miRNA biosynthesis.The followings are the main results.1.Clone and analysis of MdSE gene.In this paper,we cloned SE in apple.By analyzing the expression level of Md SE,we found that MdSE expressed in root,stem,leaf,flower and fruit and expressed most in flower.The expression level of MdSE was gradually decreased under drought stress,which indicated that MdSE might play role in drought stress.2.MdSE can negatively regulate drought resistance of apple by regulating the stomata aperture.The stomata movement of MdSE RNAi(RNA interference)transgenic apples were sensitive to ABA stimuli while the stomata of MdSE overexpression transgenic apples were insensitive to ABA stimuli.ABA plays important role in response to drought stress.The mRNA level of MdNCED3,the key gene of ABA biosynthesis,was higher in MdSE RNAi apples than wild type and overexpression apples.So MdSE can negatively regulate drought resistance of apple by regulating the stomata aperture.3.MdSE can affect the biosynthesis of miRNA.MdSE interact with MdHYL1.The expression level of pri-mi RNAs were higher in MdSE RNAi transgenic apples than wild type and the expression level of mature miRNAs were lower in MdSE RNAi transgenic apples than wild type,which indicated that MdSE affected the biosynthesis of miRNA.