峨眉拟单性木兰B类基因的克隆及系统进化分析

Cloning and Phylogenetic Analysis of B-class MADS-Box Gene in Parakmeria omeiensis

MADS-box基因是一类在花发育进程中起重要作用的基因。本研究通过同源克隆技术从峨眉拟单性木兰花芽中分离得到3个B-class MADS-Box基因的CDS全长,分别命名为PaomAP3、PaomPI1、PaomPI2,并对其进行生物信息学分析。结果表明,PaomAP3基因ORF(开放阅读框)长度为642 bp,编码214个氨基酸;PaomPI1基因ORF长度为633 bp,编码210个氨基酸;PaomPI2基因ORF长度为636 bp,编码211个氨基酸。氨基酸序列分析结果表明,三个基因均含有典型的MADS结构域及K结构域。PaomPI1、PaomPI2基因末端有典型的PI-derived保守基元,PaomAP3基因末端有Paleo AP3保守基元和PI-derived保守基元。木兰科植物在科内分类上存在很大争议,因此本研究利用MEGA6软件中最大简约法(MP)构建了部分木兰科植物B类基因的系统发育树,结果表明玉兰亚属与木兰亚属亲缘关系较远;拟单性木兰属独成一属,其与含笑属、玉兰亚属亲缘关系较近,而与木兰亚属亲缘关系较远。

MADS-Box gene is a kind of vital gene which plays an important role in flower development.In this study,3 B-class MADS-Box genes of CDS full length were isolated and cloned from the flower buds of Parakmeria omeiensis by using homologous cloning technique,named as PaomAP3,PaomPI1,PaomPI2,respectively.Meanwhile,bioinformatics analysis was carried out.The results showed that PaomAP3 contained a complete ORF（open reading frame） of 642 bp that encoded 214 amino acids;PaomPI1 contained a complete ORF of 633 bp that encoded 210 amino acids;PaomPI2 contained a complete ORF of 636 bp that encoded 211 amino acids.The results of amino acid sequence analysis showed that these 3 genes contained typical MADS domain and K domain.The PaomPI1 and PaomPI2 genes both had typical PI-derived conserved motifs,and the PaomAP3 gene ended with Paleo AP3 conserved motifs and PI-derived conserved motifs.There is a great deal of controversy about the classification of Magnoliaceae.Therefore,the phylogenetic tree of B-class genes in some Magnoliaceae plants was constructed by the maximum parsimony meth od（MP） in MEGA6 software.The results showed that the subgenus Yulania was genetically distinct from the subgenus Magnolia.The Parakmeria was a solitary genus with close relationship with Michelia L.and Subgenus Yulania,but far from Magnolia subgenus.