陆地棉与斯特提棉六倍体后代性状鉴定及抗旱基因图谱分析OA

[Objective]Distant hybridization and polyploidization are important pathways for plant speciation and crop germplasm innovation.Previously,our laboratory obtained fertile allohexaploid by distant hybridization of G.hirsutum and G.sturtianum and doubling.Through nearly ten years of greenhouse overwintering,it was found that the allohexaploid has cold and drought resistance.This study aimed to analyze the drought resistance mechanisms of the allohexaploid.[Methods]Morphological and cytological identifications were performed on different generations of the allohexaploid.Simultaneously,transcriptome sequenc-ing analysis was conducted on the S1 generation under drought stress during the squaring stage.[Results]Morphological identifi-cation showed that no significant difference existed in leaf related traits between S1 and S2,but there were significant differences between the allohexaploid and the F1 hybrid in terms of leaf area,leaf shape index,chlorophyll content,etc.Analysis of stoma-tal traits on the lower epidermis revealed that as ploidy increased,stomatal density decreased,guard cell length increased,and the number of chloroplasts significantly increased(19.73 and 19.33 in S1 and S2,respectively),further confirming the authen-ticity of the allohexaploid.The transcriptome sequencing results showed that 2302 differentially expressed genes were upregu-lated and 2681 were downregulated.After drought stress,the number of downregulated genes was higher than that of upregu-lated ones.GO enrichment analysis revealed that differentially expressed genes were mainly annotated to transcriptional regula-tion of DNA and cellular macromolecular biosynthesis pathways.Through functional annotation and enrichment analysis,eight candidate genes related to cotton drought resistance were screened.A DNA repair-related genes(TRINITY_DN8596_c0_g1)was specifically up-regulated under drought,revealing that the allohexaploid may resist drought-induced oxidative damage by enhancing genomic stability.[Conclusion]This study provided a theoretical basis for analyzing mechanisms and new germplasm materials for drought-resistant breeding in cotton.