Cloning and Evolutionary Analysis of Homologous Sequences of LEAFY Gene in Capsella bursa-pastoris (Cruciferae)
荠菜LEAFY同源基因的克隆与进化分析

LEAFY 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 LEAFY 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 of codon,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.