茄子果色相关阿罗酸脱水酶基因的鉴定与表达分析

Identification and Expression Analysis of Arogenate Dehydratase Genes Related Fruit Color in Eggplant

花青苷合成是植物苯丙烷类代谢途径的重要部分,苯丙烷代谢的前体物质苯丙氨酸合成最后一步反应的阿罗酸脱水酶(arogenate dehydratase,ADT)被认为是影响苯丙氨酸可用率的关键酶。本研究根据茄子基因组数据库基因注释检索ADT基因,并将茄子ADT基因氨基酸序列和拟南芥ADT基因编码的氨基酸序列进行同源比对、进化树分析;然后选取了6种不同果皮颜色的茄子自交系为试材,利用qPCR技术分析了ADT基因家族各成员在不同茄子果皮中的表达模式。结果表明,在茄子全基因组水平上鉴定到5个ADT基因,除SmADT3外,其余4个ADT基因编码的氨基酸序列高度保守。进化树分析表明,茄子SmADT2和SmADT5聚为1类,SmADT1和SmADT4聚为1类;其次,茄子SmADT1和拟南芥AtADT1高度同源,茄子SmADT4和拟南芥AtADT2高度同源。基因表达分析发现5个茄子SmADT基因在6种不同颜色果皮中均有表达,其中紫色品种中的表达量和花青苷合成关键酶基因SmANS、SmF3’5’H、SmDFR的表达趋势相同。相关性分析表明仅有SmADT2基因的表达量和6种茄子的果皮花青苷相对含量呈正相关。根据上述结果可推测SmADT2基因可为茄子花青苷合成的关键酶--阿罗酸脱水酶基因。

Anthocyanin biosynthetic pathway is one of the importa nt parts branching off from phenylethane metabolism,arogenate dehydratase is the key enzyme responsible for the phenylalanine biosynthesis which is the precursor substance of the phenylethane metabolism pathway and contributes to the utilization rate of prephenic acid.In this study,ADT genes were searched from the eggplant genome database,and then the alignment and phylogenetic analysis of amino acid sequences between eggplant,tomato and Arabidopsis thaliana were processed;finally,the study selected 6 eggplant inbred lines with different peel colors as test materials,and analyzed the expression patterns of ADT gene family members in different peel by qPCR.The results revealed that five ADT genes were identified in the whole eggplant genome,and the four ADT genes were highly conserved except for SmADT3.The phylogenic tree showed that SmADT2 and SmADT5 were classified to the same cluster,the SmADT1 and SmADT4 were classified to the same cluster;then the SmADT1 and AtADT1 were highly homologous,the SmADT4 and AtADT2 were highly homologous.Gene expression analysis showed that five SmADT genes were all expressed in the fruit peels of six eggplant lines with different fruit colors;the expression levels of purple varieties showed the same expression trend with the key structural genes in the anthocyanin pathway such as SmANS,SmF3'5'H,SmDFR.Correlation analysis showed that only the expression of SmADT2 gene was positively correlated with the relative content of anthocyanin in pericarp of six kinds of eggplant.The results suggest that SmADT2 gene should be the key arogenate dehydratase gene which participated in the anthocyanin biosynthesis.