Based on four RZs transcripts from the transcriptome library of Malus prunifolia under drought stress,a new gene MpRZ1 was cloned by electren extension and RT-PCR methods.The structural and functional characteristics of the deduced amino acid sequence of MpRZ1 gene was analyzed using bioinformatics methods,and a comparative analysis of MpRZ1 protein with predicted apple ( Malus domestica ) RZ homologous members was conducted.The expression pattern of MpRZ1 gene under drought stress was conducted by qRT-PCR technology.The results indicated that,cDNA sequence of MpRZ1 gene was 930 bp in length contained an intact open reading frame of 843 bp,encoding a polypeptide of 280 amino acid residues with a predicted molecular mass of 30.97 kDa and pI of 9.37.N-terminal signal peptide and transmembrane topology were not found in MpRZ1 protein,which was probably located in the nucleus and an unstable alkaline hydrophilic protein containing 38 potential phosphoryl-ation sites,13 O-GlcNAc and 5 N-Glyc potential glycosylation sites.The secondary element of MpRZ1 protein was mainly characterized by random curling and α-helice,accounting for up to 87.1%.The predicted MpRZ1 protein contained one conserved RNA-recognition motif ( RRM) with five antiparallel β-strands and 2 α-helices arranged in β1α1β2β3α2β4β5 topology at the N-terminus,and a CCHC type zinc finger domain as well as a series of ( GGX) n and ( DRY/F) n repeated at the C-terminal glycine-rich region.Sequence alignment and phylogenetic a-nalysis indicated that the predicted MpRZ1 protein shared higher sequence similarity and homology with Arabidopsis and rice RZ proteins,suggesting this MpRZ1 gene belonged to a homologous member of RZ genes family.Nine dif-ferent MdRZs transcripts found in the apple genome uniformly encoded alkaline hydrophilic proteins,and this MpRZ1 protein had more than 96% homology with two MdRZs proteins encoded by MdP0000088428 and MdP0000272138 transcripts.The expression level of RZ genes in leaves of M.prunifolia and M.hupehensis at 9 days of drought stress and showed significant differences compared to the control (P<0.05),indicating that the MpRZ1 gene was involved in the drought stress response process.
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