绿豆R2R3-MYB转录因子家族鉴定及其类黄酮合成调控基因的筛选

Identification of the R2R3-MYB transcription factor family and screening of genes regulating flavonoid synthesis in mung bean

R2R3-MYB转录因子家族在植物次生代谢物合成、胁迫应答和生长发育等生命过程起着重要的调控作用。本研究基于生物信息学鉴定了绿豆(Vigna radiata L.)全基因组水平的R2R3-MYB转录因子,并对其理化性质、系统进化、染色体定位、启动子顺式作用元件及基因结构做了预测分析;此外,转录组数据和实时荧光定量PCR(QuantitativeReal-timePCR,RT-PCR)分析该转录因子在不同组织、逆境胁迫下的表达模式;并基于相关分析及蛋白互作网络,筛选到可能参与调控绿豆类黄酮生物合成的R2R3-MYB成员。结果表明,共鉴定到168个R2R3-MYB成员,其中145个分布于11条染色体, 23个成员染色体信息未知;大多数R2R3-MYB含有3个外显子,编码99~1645个氨基酸,均为亲水性蛋白;系统进化将绿豆R2R3-MYB基因家族分为30个亚组(V1~V30),不同亚组成员的基因结构存在差异;共线性分析表明,片段复制事件均进行了纯化选择;启动子顺式作用元件分析表明,绿豆R2R3-MYB基因启动子区含有大量激素响应、胁迫响应及少量的类黄酮合成响应等元件;基因表达分析表明,在叶片、叶柄、下胚轴和籽粒种皮中表达量较高的成员分别占15.5%、16.1%、16.1%和10.7%。RT-PCR分析发现,几乎所有的R2R3-MYB家族成员在低温胁迫下的相对表达量显著下调,不同成员对逆境胁迫有不同的响应模式。蛋白互作与相关性分析可知,VrMYB6、VrMYB77、VrMYB93这3个基因可能参与了绿豆类黄酮生物合成的调控。

The R2R3-MYB transcription factor family plays a crucial regulatory role in the synthesis of secondary metabolites,stress responses,and the growth and development of plants.This study employed bioinformatics analysis to identify the R2R3-MYB transcription factors across the entire genome of mung bean(Vigna radiata L.),and to predict their physicochemical properties,phylogenetic evolution,chromosome localization,cis-acting elements of the promoter,and gene structure.The expres-sion patterns of mung bean under different tissues,exogenous hormones,and stress conditions were analyzed using transcriptome data and Quantitative Real-time PCR(RT-PCR).R2R3-MYB members potentially involved in regulating the biosynthesis of mung bean flavonoids were screened through correlation analysis and protein interaction networks.The results demonstrated that a total of 168 R2R3-MYB members were identified in mung bean,145 of which were distributed across 11 chromosomes,while the chromosome information for 23 members remains unknown.Most of these members contain three exons encoding proteins ranging from 99 to 1645 amino acids and are all hydrophilic.The phylogenetic analysis divided the R2R3-MYB gene family in mung beans into 30 subgroups(V1-V30),revealing structural differences among members of different subgroups.Collinearity analysis within the mung bean genome indicated that all segmental duplication events underwent purifying selection.Analysis of cis-acting elements in the promoter regions of the R2R3-MYB genes in mung beans revealed a large number of hor-mone-responsive and stress-responsive elements,as well as a small number of flavonoid synthesis-responsive elements.Gene expression analysis showed that members with higher expression levels in leaves,petioles,hypocotyls,and seed coats accounted for 15.5%,16.1%,16.1%,and 10.7%of the total,respectively.RT-PCR analysis indicated that the relative expression levels of almost all R2R3-MYB family members significantly decreased under low-temperature stress,with different members had diverse response patterns to stress.Protein interaction and correlation analysis suggested that the genes VrMYB6,VrMYB77,and VrMYB93 may be involved in the regulation of flavonoid biosynthesis in mung beans.The results of this study lay the foundation for further in-depth research on the function of the R2R3-MYB transcription factor family in mung beans.