Abstract: GH9 genes play  vital roles in the biosynthesis and remodeling of plant cell walls. The aim of this study was to discover fiber development-related GH9 genes by the identification and analysis of this gene family in Gossypium barbadense. A total of 53 GH9 genes were identified from Gossypium barbadense, and their physico-chemical properties, gene structure, chromosomal distribution and evolutionary history were analyzed. This paper also investigated the expression patterns and transcriptional regulation of GbGH9s during cotton fiber development. As a result, 53 GbGH9s were divided into three groups (A, B and C) and were distributed on 22 chromosomes. The expansion of GH9 gene family was mainly driven by polyploidization in Gossypium barbadense, and the duplicated genes had been under strong selective constraints. Some members of group A showed high expression levels during cotton fiber development, especially during secondary wall thickening. Some members of group C were highly expressed during cotton fiber initiation and elongation. In addition, the expression patterns of group B were relatively complex. Auxin and ethylene may have played important roles in the transcriptional regulation of GbGH9s. It improved cotton fiber strength by the introgression of GbGH9B6 into Gossypium hirsutum. The identification and analysis of GbGH9s were critical for understanding their evolution and functions, and provided a support for future studies.

Key words: Gossypium barbadense, GH9 gene family, evolution, expression analysis, cotton fiber development

摘要： 植物GH9基因在细胞壁的生物合成和重塑中起着重要作用，对海岛棉GH9基因进行全基因组鉴定与分析，挖掘其在棉纤维发育中的作用。从海岛棉全基因组中鉴定到53个GH9基因，分析其理化性质、基因结构、染色体分布、进化历程、棉纤维发育过程中表达模式及转录调控。结果表明，53个GbGH9s分为A、B、C三组，定位在22条染色体上；多倍化事件是海岛棉GH9基因家族扩张的主要驱动力，基因复制后经历严格的选择约束；A组多个成员在棉纤维发育整个时期尤其是次生壁加厚期高表达，C组多个成员在棉纤维起始和伸长期优势表达，B组具有相对复杂的表达模式，生长素和乙烯可能在GbGH9s的转录调控中发挥重要作用。此外，通过回交将GbGH9B6导入陆地棉可提高棉纤维强度。海岛棉GH9基因家族成员的鉴定及分析有助于明确其进化和功能，为后续研究提供重要参考。

关键词: 海岛棉, GH9基因家族, 进化, 表达分析, 棉纤维发育