大豆Abhydrolase_3基因家族进化分析

异黄酮是大豆的重要次生代谢物,参与植物与微生物互作。2-羟基异黄酮脱水酶(hydroxyisoflavanone dehydratase,HID)催化2-羟基异黄酮形成稳定的异黄酮。HID属于Abhydrolase_3基因家族,该基因家族具有多种功能,但该基因家族在大豆中的进化模式尚待研究。为了研究Abhydrolase_3基因家族在大豆中的进化模式,本文在大豆基因组中鉴定了62个Abhydrolase_3基因,串联和片段复制是该基因家族主要扩增方式。根据系统进化关系,将大豆Abhydrolase_3基因家族划分为8个亚家族,其中HID所在的亚家族I基因数量最多,并发生多次基因扩增事件。对大豆Abhydrolase_3基因家族结构分析表明,不同亚家族具有不同的基序。多态性分析表明,亚家族Ⅰ、Ⅲ和Ⅴ具有较高的核苷酸差异,并受到放松的自然选择。基因表达分析表明,除了亚家族II和IV外,其它亚家族的基因在大豆不同组织中有较高表达;亚家族Ⅰ、Ⅲ、Ⅳ、Ⅴ和Ⅵ基因受病原菌诱导表达。结果说明HID所在的亚家族I存在基因扩增和功能分化,与病原菌互作相关的基因具有较高的遗传多样性并受病原菌诱导表达。

Evolution Analysis of Abhydrolase_3 Gene Family in Soybean

Isoflavonoids are important secondary metabolites of soybean and involved in the interactions with pathogens.2-hydroxyisoflavanone dehydratase (HID) catalyzes the dehydration of 2-hydroxyisoflavanones to the formation of stable isoflavonoids.HID belongs to the Abhydrolase_3 gene family,which is involved in plenty of functions.To study the evolutionary patterns of Abhydrolase_3 gene family in soybean,62 Abhydrolase_3 genes were identified from soybean genome.Tandem and segmental duplications are the primary duplicated patterns of this gene family.Based on the phylogenetic relationships,eight subfamilies were classified.Subfamily Ⅰ contains the largest number of genes,in which several times of gene duplications occur.Genes in different subfamilies were characterized by distinct patterns of motif combinations.Genetic polymorphic analysis showed homologous genes in subfamilies Ⅰ,Ⅲ and Ⅴ possess a higher level of nucleotide diversity,and experience a relaxed selection pressure.The expression analysis showed that genes in most subfamilies except Ⅱ and Ⅳ show high levels of expression in different tissues,and the expression levels of genes in subfamilies Ⅰ,Ⅲ,Ⅳ,Ⅴ and Ⅵ were induced by pathogens.The results showed that gene expansion and functional divergence exist in subfamily Ⅰ,which contains HID,and that genes involved in the interaction with pathogens possess higher levels of genetic diversity and the expressions are induced by pathogens.