‘元帅’苹果短枝变异逆转座子插入位点临近基因Md RDACO1的表达及功能分析  

Activity and Function Analysis of MdRDACO1 Flanking the Retrotransposon Mdsolo-LTR1 Insertion Site in’Red Delicious’Apple Spur Mutants

作　　者：马福利 穆文磊 周军永[1,2] 陆丽娟[2] 孙其宝[2] 王海燕 孙俊 MA Fuli;MU Wenlei;ZHOU Junyong;LU Lijuan;SUN Qibao;WANG Hai-yan;SUN Jun(College of Horticulture,Anhui Agricultural University,Hefei 230036,China;Horticulture Research Institute,Anhui Academy of Agriculture Sciences,Hefei 230031,China;State Key Laboratory of Tea Plant Biology and Utilization,Hefei 230036,China)

机构地区：[1]安徽农业大学园艺学院,合肥230036 [2]安徽省农业科学院园艺研究所,合肥230031 [3]茶树生物学与资源利用国家重点实验室,合肥230036

出　　处：《园艺学报》2020年第8期1429-1437,共9页Acta Horticulturae Sinica

基　　金：国家自然科学基金项目(31372043,31071776)。

摘　　要：前期研究发现在‘元帅’苹果短枝突变体4号染色体约3768578 bp处存在一个2190 bp的逆转座子Mdsolo-LTR1及其插入位点3’端约50 kb处有一乙烯合成限速酶基因ACO1。以‘元帅’及其短枝突变品种‘奥勒冈矮生’为试材,研究逆转座子Mdsolo-LTR1对其临近基因MdRDACO1表达活性的影响。荧光定量PCR结果表明,MdRDACO1的表达量在新梢发育至9节和12节时的顶芽和新梢半木质化前各阶段的茎段中均是‘元帅’显著高于‘奥勒冈矮生’。拟南芥异源转化结果显示,播种后7 d时,转Md RDACO1基因株系下胚轴长度和45d时株高显著高于野生型和转空载株系;进一步分析发现,转Md RDACO1株系中古巴焦磷酸合成酶基因AtCPS1的表达量显著高于野生型和转空载株系。试验结果暗示‘奥勒冈矮生’等短枝突变体中,逆转座子Mdsolo-LTR1可能通过抑制其临近的乙烯合成限速酶基因Md RDACO1的表达活性,从而抑制受乙烯正调控的赤霉素合成关键基因Md CPS活性,进而导致短枝突变。In our previous study,a Mdsolo-LTR1 insertion was identified as a spur-specific solo LTR(long terminal repeat)located at position 3768578 bp on apple chromosome 4 in’Red Delicious’apple spur mutants.The 1-aminocyclopropane-1-carboxylate oxidase(ACO1)gene,which encoded the rate-limiting enzyme synthesizing ethylene,was localized at approximately 50 kb downstrem of Mdsolo-LTR1 insertion site in spur mutants.In the present study,activity and function analysis of Md RDACO1 flanking the retrotransposon Mdsolo-LTR1 insertion site was further confirmed.The real-time PCR analysis showed that the expression levels of MdRDACO1 in apical bud(L9–L12)and stem(before shoot half lignification)of’Red Delicious’were higher than those of in’Oregon spur Delicious’.The function of MdRDACO1 gene was investigated by Agrobacterium-mediated genetic transformation into Arabidopsis.Overexpression of MdRDACO1 gene significantly increased hypocotyl elongation,plant height and the expression level of AtCPS1 gene in transgenic lines.Our results suggested that spur mutants could partly be attributed to Mdsolo-LTR1 insertion,which represses the expression activity of nearby Md RDACO1 gene,down-regulating the expression activity of MdCPS to synthesize gibberellins in spur mutants.

关 键 词：苹果 短枝突变 逆转座子 基因表达 

分 类 号：S661.1[农业科学—果树学]