[目的]β-微管蛋白是棉纤维细胞形态建成的基本结构单位,在纤维发育过程中具有重要作用.通过鉴定棉花β-tubulin基因家族成员,并进行生物信息学和表达模式分析,为深入探究β-tubulin基因在棉花纤维发育中的作用提供理论依据.[方法]利用BLAST方法,在4个棉种基因组中鉴定β-tubulin基因家族成员,并结合ProtParam tool分析理化性质、MEGA7.0构建系统进化树、Mapchart2.2绘制染色体定位图、MEME分析保守基序、PlantCARE分析启动子顺式作用元件;根据39个材料发育纤维转录组数据分析陆地棉β-tubulin基因家族的表达水平,并利用Spearman相关性分析鉴定影响纤维品质性状形成的β-tubul in基因.[结果]在陆地棉(Gossypiumhirsutum,AD1)、海岛棉(Gossypium barbadense,AD2)、亚洲棉(Gossypium arboretum,A2)和雷蒙德氏棉(Gossypium raimondii,D5)基因组中分别鉴定到 36、37、19和18个β-tubulin基因,且在四倍体棉种中的数目约是二倍体棉种数目的二倍,系统进化将其分为Cluster I-ClusterV共5个亚组.系统进化与共线性分析发现,与陆地棉β-tubulin基因家族相比,海岛棉与二倍体亚洲棉和雷蒙德氏棉亲缘关系更近.保守结构域均具有典型的Tubulin和Tubulin-C.理化性质分析表明,该家族基因编码的氨基酸数目为421-508,等电点为4.68-5.09.启动子顺式作用元件分析获得生长发育响应相关元件、激素响应相关元件和胁迫响应相关元件等,表明β-tubulin基因参与细胞的生长调节.利用TM-1转录组数据对36个陆地棉β-tubulin基因表达模式进行聚类分析,发现有42%基因在纤维中优势表达;此外,利用海陆群体动态纤维转录组数据筛选到1、6和11个β-tubulin基因分别与纤维马克隆值、比强度和纤维长度显著相关,其中4个基因同时影响纤维长度和比强度性状.[结论]4个棉种中共鉴定出110个β-tubulin基因家族成员,氨基酸理化性质和序列高度保守而启动子序列调控元件多样;筛选出陆地棉纤维优势表达的β-tubulin基因家族成员,并发掘潜在调控纤维发育的候选基因.
[Objective]β-tubulin is the basic structural unit of cotton fiber,regulates fiber cell morphogenesis,and plays a vital role in fiber development.But there is less understood how β-tubulin gene influenced the distinct characteristic of fiber quality traits in cotton.In this study,members of the β-tubulin gene family were identified in cotton,their expression profiles were analyzed,and role of β-tubulin genes were explored for fiber quality.[Method]BLAST method was used to identify members of the β-tubulin gene family in the genomes of four cotton species.ProtParam tool was utilized to analyze physicochemical properties,MEGA7.0 to construct phylogenetic tree,Mapchart2.2 to draw chromosomal localization map,MEME to analyze conserved motif,and PlantCARE to analyze promoter cis-acting elements.Expression levels of β-tubulin genes were characterized by using transcriptome data from 39 studies on fiber development.Spearman correlation analysis was used to identify candidate genes for fiber quality traits.[Result]Importantly,36,37,19 and 18 β-tubulin genes were identified in the genomes of Gossypium hirsutum(AD1),Gossypium barbadense(AD2),Gossypium arboretum(A2)and Gossypium raimondii(D5),respectively.The number of β-tubulin genes in tetraploid cotton species is almost double than that of diploid cotton species.Phylogenetic analysis classified these genes into 5 main clusters.Phylogenetic and collinearity analysis revealed that β-tubulin genes in Gossypium barbadense is closely related to Gossypium arboretum and Gossypium raimondii as compared to Gossypium hirsutum.Furthermore,all genes have typical conservative domains with Tubulin and Tubulin-C.The genes physicochemical properties showed amino acids range from 421 to 508 with isoelectric point of 4.68 to 5.09.The analysis of promoter cis-acting elements identified growth responsive,hormone responsive,and stress responsive elements which showed β-tubulin mediates various mechanisms of cell growth regulation.Interestingly,cluster analysis on 36 β-tubulin gene expression profiles showed 42%genes in cluster Π had dominant expression in fiber.In particular,1,6,and 11 β-tubulin genes exhibited significant correlation with fiber micronaire value,fiber strength,and fiber length,respectively.Four genes were found to influence fiber length and fiber strength traits simultaneously.[Conclusion]A total of 110 β-tubulin gene family members were identified in the four cotton species.Their physicochemical properties and sequences of amino acids were highly conserved and the promoter sequence had diverse regulatory elements.This study characterized the expression profiles as well as molecular function of β-tubulin gene family in cotton fiber.Further discovered the potential candidate genes that probably regulate fiber quality traits in cotton.Our results may have great potential for cotton fiber quality improvement by genetic engineering.