棉花EXO70基因家族全基因组的鉴定及种间比较

Genome-Wide Identification and Interspecific Comparative Analysis of the EXO70 Gene Family in Cotton

【目的】当前四倍体棉花的主栽品种是陆地棉与海岛棉,陆地棉产量高且适应性好,海岛棉纤维品质优异但产量一般。EXO70是胞外分泌体(exocyst complex)中的关键亚基,在植物生长发育、胁迫响应等方面发挥重要作用。通过全基因组水平鉴定和分析陆地棉与海岛棉EXO70基因家族成员,并研究其在纤维发育、环境适应等方面的功能,有助于揭示陆地棉与海岛棉种间性状差异形成的分子基础。【方法】从拟南芥数据库(TAIR)获取EXO70家族蛋白序列作为参考序列,采用HMMER、ExPASy、MEME、TBtools等分析工具对陆地棉TM-1和海岛棉Hai7124基因组中EXO70家族成员进行鉴定与分析,系统比较该家族在基因表达模式、重要农艺性状的相关性、逆境响应等方面的异同点。【结果】通过对陆地棉和海岛棉的基因组水平分析,均鉴定出54个EXO70家族成员,根据系统进化发育可将其分为8个分支。陆地棉和海岛棉同源基因可一一对应,分布在陆地棉与海岛棉的20条染色体上,绝大多数成员为单外显子,但是两者间有12对同源基因在阅读框序列上存在较大差异。陆地棉与海岛棉大部分同源基因表达模式类似,但在同一纤维发育时期表达量存在差异,如分支A中的GH_A04G1208与同源基因GB_A04G1253。重要农艺性状关联分析中发现,海岛棉有16个EXO70基因与纤维品质性状显著相关,多于陆地棉;陆地棉有13个基因与产量性状衣分显著相关,多于海岛棉。发现部分性状关联的差异可能由海陆种间的基因结构差异造成,如GH_A11G3714和GB_A11G3791。在不同逆境胁迫下,陆地棉中有25个基因受诱导,显著多于海岛棉中10个受诱导基因。【结论】在棉花四倍体形成、分化与驯化过程中,陆地棉与海岛棉EXO70家族基因序列结构相对保守,基因表达模式也保持较高的一致性。海岛棉有更多的EXO70基因与纤维品质性状相关,陆地棉有更多的基因与产量性状相关且对环境逆境更为敏感。

【Objective】The two main types of allotetraploid cotton that are currently cultivated are upland cotton,known for its high yield and good adaptability,and island cotton,which boasts excellent fiber quality but lower yield.EXO70,a vital subunit of the exocyst complex,plays a significant role in plant growth,development,and stress response.By identifying and analyzing members of the EXO70 gene family in upland and island cotton at the whole-genome level,and studying their functions in fiber development and environmental adaptation,we can shed light on the molecular basis for the differences in traits between these two varieties.【Method】The reference sequences of EXO70 protein in Arabidopsis were obtained from the TAIR database.HMMER,ExPASy,MEME,TBtools,and other analysis tools were used to identify and analyze the members of EXO70 gene family in the genomes of upland cotton TM-1 and island cotton Hai7124.The similarities and differences in gene expression patterns,correlations with crucial agronomic traits,and stress responses of this family were systematically compared.【Result】Through genome-level analysis of upland cotton and sea-island cotton,54 EXO70 family members were identified in both upland and sea-island cotton,which could be divided into eight subgroups based on phylogenetic analysis.Orthologous genes between upland cotton and sea-island cotton can be paired one-to-one and are distributed across the 20 chromosomes of both species.The majority of the members have single exons,while 12 pairs of homologous genes displayed significant differences in the reading frame sequences.Most orthologous genes in Gossypium hirsutum and Gossypium barbadense display similar expression patterns,but differences in expression levels are observed during the same fiber development stage,such as GH_A04G1208 and its orthologous gene GB_A04G1253 in subgroup A.Single gene association analysis revealed that more genes were associated with fiber quality traits in sea-island cotton,while more genes were associated with yield traits and environmental adversity sensitivity in upland cotton.Some trait association differences resulted from genetic structural differences between Gossypium hirsutum and Gossypium barbadense.Under different stresses,upland cotton showed a significantly higher number of induced genes compared to sea-island cotton.【Conclusion】The sequence structure and gene expression patterns of the EXO70 family were found to be relatively conserved in both upland and island cotton during the formation,differentiation,and domestication of tetraploid cotton.However,in terms of EXO70 family members,island cotton had more genes related to fiber quality traits,while upland cotton had more genes related to yield traits and exhibited greater sensitivity to environmental stress.