Characterization and Expression Analysis of MADS-box gene AGL8 in Cotton: Insights into gene function differentiation in plant growth and stress resistance

Background AGAMOUS-LIKE 8 (AGL8) belongs to the MADS-box family, which plays an important role in transcriptional regulation, sequence-specific DNA binding and other biological processes and molecular functions. As a representative of polyploid plants, cotton genome contain multiple AGL8 genes. However, their differentiation in function is still unclear. Methods and Results This study conducted a comprehensive genomic analysis of AGL8 genes. Cotton AGL8s were subdivided into four subgroups (Groups 1, 2, 3, and 4) based on phylogenetic analysis, and different subgroups of AGL8s showed different characteristics, including structure and conserved motifs. In the promoter region of GhAGL8 genes, we successfully predicted cis-elements that respond to phytohormone signal transduction and stress response of plants. Based on transcriptome data and real-time quantitative PCR validation, the results indicated that three genes, GH_D07G0744, GH_A03G0856 and GH_A07G0749, were highly induced by MeJA, SA, and ABA, which indicated that they function in plant resistance to abiotic and biological stresses. Conclusions The information from gene structure, number and types of conserved domains, tissue-specific expression levels, and expression patterns under different treatments indicates the differentiation of sequence and function in cotton AGL8 genes. Different AGL8s play a role in vegetative growth, reproductive development, and plant stress resistance.These results laid a foundation for further study of GhAGL8s in cotton.