荠菜LEAFY同源基因的克隆与进化分析  

Cloning and Evolutionary Analysis of Homologous Sequences of LEAFY Gene in Capsella bursa-pastoris(Cruciferae)

作　　者：周贤龙[1] 王小兰[2] 王武源[3] 葛学军[4] 

机构地区：[1]中国科学院华南植物园 [2]广州大学功能基因与芯片研究中心,广州510405 [3]江西农业工程职业学院,樟树331200 [4]中山大学生命科学学院,广州510275

出　　处：《热带亚热带植物学报》2006年第2期113-119,共7页Journal of Tropical and Subtropical Botany

基　　金：广东省自然科学基金项目(05006754);广东省自然科学基金博士启动项目(04300465)

摘　　要：LEAFY同源基因是高等植物花的分生组织分化的重要调节基因。根据已发表的LEAFY同源基因序列保守区设计引物,以荠菜(Capsellabursa-pastoris(L.)Medic.)基因组DNA序列为模板,克隆了一条长2866bp的LEAFY同源基因。序列分析表明,该基因含有3个外显子和2个内含子,外显子编码424个氨基酸组成的多肽。其单个外显子核苷酸序列与拟南芥(Arabidopsisthaliana)LEAFY基因同源性在90%以上,氨基酸序列同源性为86%,而与琴叶拟南芥(Ara-bidopsislyrata)的氨基酸序列同源性高达90%。不同植物物种的LEAFY同源氨基酸序列在C端高度保守,而N端则有较大程度的变异。3个外显子进化速率不同可能是由于所受选择压力不同所致。存在于荠菜CapLFY基因346位上的精氨酸突变可能是造成荠菜两种生态型花期不同的原因。LEA FY is an important regulator of floral meristems genes in higher plants. To investigate its origin and evolution, a LEAFY homologs with length of 2 866 bp was cloned from Capsella bursa-pastoris genome using the conserved primers from Arabidopsis thaliana LEAFY gene. Sequence analysis indicated three exons with the length of 457 bp, 407 bp and 411 bp. These exons encoded a protein of 424 amino acids. The single exon was more than 90% homologous to A. thaliana LEA FY gene, and the amino acid homology was 86%. When compared to Arabidopsis lyrata LEAFY gene, there was 93 nucleotide substitution in the exons of C. bursa-pastoris, and 74.7% of these mutations located at the third position ofcodon, the amino acid homology reached 90%. Among the three exons, Ds/Dn ratio was 1.9, 2.3 and 6.0. Homologous comparison indicated that the C-terminal amino acids were highly conserved among different plant species while the great variation existed in N-terminal. In addition, the Arg mutation located at 346 in CapLFY gene was speculated to be one of main reasons that caused the ecotypes with different flowering time in C. bursa-pastoris.

关 键 词：荠菜 LEAFY基因 克隆 进化分析 

分 类 号：Q943[生物学—植物学]