苹果生长素运输基因MdABCB19的克隆及其在矮化砧木中的表达分析

以苹果矮化砧木M9和乔化砧木MM106为材料,克隆到一个3 753 bp的核苷酸序列,其编码1 250个氨基酸,含有两个ABC_membrance结构域,两个ABC_tran结构域,与梨、油菜和拟南芥的ABCB19基因高度同源,命名为MdABCB19。该序列在M9和MM106中存在一个非同义SNP,编码氨基酸由A突变为S,导致M9α螺旋少了一段。表达量分析表明,MdABCB19在砧木M9和MM106、长富2号/M9和长富2号/MM106均差异表达。启动子序列分析发现M9的MdABCB19启动子在起始密码子上游170 bp处有6个碱基(CTCTGT)缺失,导致缺失一个5'UTR Py-rich stretch motif。MM106的MdABCB19启动子活性高于M9,并且受光照调控。推测M9的MdABCB19启动子5'UTR Py-rich stretch motif缺失可能与其MdABCB19低表达有关;而氨基酸突变导致蛋白质三级结构α螺旋结构改变是否影响生长素运输,有待进一步研究。上述研究表明苹果MdABCB19可能通过调控生长素转运参与砧木苗矮化性状的调控。

Isolation and Expression Analysis of MdABCB19 Gene and Its Promoter from Dwarfing Apple Rootstock

Apple dwarfing rootstock M9 and vigorous rootstock MM 106 were used as the material to clone a 3 753 bp nucleotide sequence encoding a length of 1 250 amino acids.The fragment named as MdABCB19 because of high homology with apple (XP 008341564.1),pears (XP 009347047.1),rape (XP 009151836.1),and Arabidopsis (AT3G28860.1) protein sequence of ABCB19.MdABCB19 sequence in M9 and MM106 presented of non-synonymous SNP,leading to the amino acid sequence different at the 885th amino acids:M9 serine (Ser),MM 106 alanine (Ala).Protein structure analysis found that the amino acid point mutations,leading to a shorter alpha helix in M9.Real time quantitative expression analysis showed that,MdABCB19 were differentially expressed in the rootstock M9 and MM 106 MdABCB19 were also cloned and found" CTCTGT"6 bp deletion at about the 170 bp upstream of the start codon of M9 MdABCB19 promoter,resulting in missing a 5'UTR Py-rich stretch motif.Promoter cis-acting element analysis shown MdABCB19 promoter region contained several light response motifs.Promoter GUS staining shown that MM106 MdABCB19 promoter activity was higher than M9.The MdABCB19 promoter were regulated by light.M9 MdABCB19 promoter 5'UTR Py-rich stretch motif deletions may induce in MdABCB19 low expression in M9.