云南栘[木衣]R2R3-MYB转录因子鉴定与表达分析

Identification and expression analysis of R2R3-MYB transcription factors in Docynia delavayi

【目的】R2R3-MYB转录因子是植物中重要的一类转录因子,在调节色素积累方面发挥着重要作用。云南栘[木衣]存在显著的果皮颜色变异,通过分析R2R3-MYB转录因子在3种变异类型果皮的表达模式,旨在筛选可能参与果皮着色的候选基因。【方法】以3种变异类型果皮为材料,基于其转录组数据对R2R3-MYB转录因子进行鉴定,并对其理化性质、系统发育、保守结构域、保守基序和表达模式进行分析。【结果】共鉴定出99个R2R3-MYB转录因子,以不稳定亲水蛋白为主,其氨基酸长度在86~881 aa之间,相对分子质量在10.21~99.63 kDa之间,等电点在5.01~11.44之间;系统发育分析显示,4个云南栘[木衣]R2R3-MYBs和苹果MdMYB10共同聚在S6亚组,说明可能参与调控植物花青素的生物合成;每位成员均含有2个R结构域,每个R结构域在进化过程中都呈现出高度的保守性;保守基序分析结果显示,motif 1~motif 4在大多数成员的N端分布,与R2、R3结构域分布特点相似;表达模式分析表明,48个差异表达的DdR2R3-MYB基因存在5种表达模式,表明DdR2R3-MYB转录因子功能具有一定的多样性。RT-qPCR分析表明,DdR2R3-MYB2/16/18在红色果皮中上调表达显著,DdR2R3-MYB47/48在黄色果皮中上调表达显著。【结论】基于系统发育及表达模式分析结果,共筛选出3个可能调控花青素生物合成和2个可能调控类胡萝卜素生物合成的候选基因,为云南栘[木衣]果皮着色相关基因的挖掘奠定理论基础。

【Objective】The R2R3-MYB genes,as one of the largest transcription factors(TFs)families in the plant kingdom,play a significant role in the regulation of pigment accumulation.The aim of this study was to screen the candidate R2R3-MYB genes involved in peel coloration,as there are remarkable variations in the pericarp’s color of Docynia delavayi(Franch.)Schneid.【Method】The pericarp of three D.delavayi types was used as the material,the R2R3-MYB genes were identified based on the transcriptomic data and subsequently analyzed for their physicochemical properties,phylogeny,conserved domains,conserved motifs and expression patterns.【Result】A total of 99 R2R3-MYB genes were identified,and most of them were hydrophilic proteins with an amino acid sequence varying from 86 to 881aa,molecular weight between 10.21 and 99.63 kDa,an isoelectric point between 5.01 and 11.44,and an aliphatic index between 55.77 and 91.78.The phylogenetic tree showed that 4 R2R3-MYBs of D.delavayi(DdR2R3-MYB)and MdMYB10 were co-clustered in the subgroup 6,suggesting a possible association with anthocyanin biosynthesis.Additionally,8 DdR2R3-MYBs were clustered in subgroup 22,indicating that they might be related to carotenoid biosynthesis.Each DdR2R3-MYB contained 2 R domains,which displayed high conservation in the evolutionary process.Conserved motif analysis showed that motif 1~motif 4 were located at the N terminus of most members,which was similar to the R2 and R3 conserved domains.Expression pattern analysis showed that the 48 differentially expressed DdR2R3-MYB genes exhibited 5 expression patterns,indicating diverse functions of DdR2R3-MYBs.RT-qPCR analysis showed that DdR2R3-MYB2/16/18 was significantly up-regulated in the red pericarp,and DdR2R3-MYB47/48 was accumulated in the yellow pericarp.【Conclusion】Based on the phylogenetic and expression pattern analyses,three candidate genes have been screened for anthocyanin biosynthesis regulation and two candidate genes were obtained for carotenoid biosynthesis regulation,which laid a theoretical foundation for the mining of the genes related to peel coloration in D.delavayi.