Cotton is a valuable cash crop in many countries. Cotton fiber is a trichome that develops from a single epidermal cell and serves as an excellent model for understanding cell differentiation and other life processes. Alternative splicing (AS) of genes is a common post-transcriptional regulatory process in plants that is essential for plant growth and development. The process of AS during cotton fiber formation, on the other hand, is mainly unknown. A substantial number of multi-exon genes were discovered to be alternatively spliced during cotton fiber formation in this study, accounting for 23.31% of the total number of genes in Gossypium hirsutum. Retention intron (RI) is not necessarily the most common AS type, indicating that AS genes and processes during fiber development are very temporal and tissue-specific. When compared to fiber samples, AS is more prevalent at the fiber initiation stages and in the ovule, indicating that development stages and tissues use different AS strategies. Genes involved in fiber development have gone through stage-specific AS, demonstrating that AS regulates cotton fiber development. Furthermore, AS can be regulated by trans-regulation elements such as splicing factor and cis-regulation elements such as gene length, exon numbers, and GC content, particularly at exon-intron junction sites. Our findings also suggest that increased DNA methylation may aid in the efficiency of AS, and that gene body methylation is key in AS control. Finally, our research will provide useful information about the roles of AS during the cotton fiber development process.
Keywords: GO enrichment; Gossypium hirsutum; alternative splicing; fiber development; methylation; transcriptome.