番茄花青素合成关键酶基因的序列与进化分析

Sequence and Evolutionary Analyses of the Genes Encoding Key Enzymes Involved in Anthocyanin Biosynthesis in Tomato( Solanum lycopersicum)

为了研究花青素在植物生长发育与响应外界环境中的作用,本研究利用生物信息学手段首次系统剖析了番茄花青素合成途径中11种关键酶基因的序列与进化特征。序列分析显示:同类关键酶具有相似的基因结构特征,其中Sl CHI、Sl F3'5'H和Sl PAL基因的外显子个数高度保守;同类关键酶的功能结构域和保守基序组成模式高度保守,但C4H、F3'H和F3'5'H酶分享p450结构域和相似的保守基序组成模式,ANS和F3H分享同样结构域和相似的保守基序组成模式。系统进化树分析显示,番茄27个花青素合成关键酶被分为8个类群,其中C4H/F3'H/F3'5'H类群能被进一步分为3个亚类群,ANS/F3H类群能被进一步分为2个亚类群。选择压力检测显示,除PAL和ANS基因受正选择作用外,剩余的9种关键酶均受到功能限制作用,未鉴定到正选择位点(P<0.05)。研究结果为进一步研究番茄及其它植物花青素合成关键酶基因的功能及其关键氨基酸位点提供理论参考。

Anthocyanin is an important pigment in plants, which played important roles in plant growth, development, and response to environmental stress. Sequence and evolutionary analyses were first conducted via bioinformatics method on 11 key genes encoding enzymes involved in anthoeyanin biosynthesis pathway in tomato. Sequence analysis showed that each type of gene encoding key enzyme had similar gene structure, and that the number of exons of the SICHI, SlF3＇5＇H and SIPAL genes were highly conserved. Accordingly, each type of enzymes had conserved domain and motif organization, but C4H, F3＇H and F3＇5＇H enzymes shared the same p450 domain and similar motif organization, and ANS and F3H shared the same domain and highly similar motif organization as well. A total of 27 genes from anthocyanin biosynthesis pathway in tomato could be divided into eight groups identified by phylogenetic analysis. C4H/ F3＇H/F3＇5＇H group could further be classified into three subgroups, and ANS/F3H group could further be divided into two subgroups. Selective pressure analysis demonstrated that PAL and ANS genes were under positive selection, but no amino acid sites under positive selection can be identified in the remaining 9 genes due to the restrictions by function. These findings provide important basis for further investigating the functions of key genes and identifying the important amino acid sites of these enzymes in tomato anthocyanin biosynthesis.