Genome-Wide Identification of the MIKC-Type MADS-Box Gene Family in L. Unravels Their Roles in Flowering.

Cotton is one of the major world oil crops. Cottonseed oil meets the increasing demand of fried food, ruminant feed, and renewable bio-fuels. MADS intervening keratin-like and C-terminal (MIKC)-type MADS-box genes encode transcription factors that have crucial roles in various plant developmental processes. Nevertheless, this gene family has not been characterized, nor its functions investigated, in cotton. Here, we performed a comprehensive analysis of MIKC-type MADS genes in the tetraploid L., which is the most widely cultivated cotton species. In total, 110 genes were identified and phylogenetically classified into 13 subfamilies. The Flowering locus C () subfamily was absent in the L. genome but is found in Arabidopsis and L. Among the genes, 108 were distributed across the 13 A and 12 of the D genome's chromosomes, while two were located in scaffolds. within subfamilies displayed similar exon/intron characteristics and conserved motif compositions. According to RNA-sequencing, most MIKC genes exhibited high flowering-associated expression profiles. A quantitative real-time PCR analysis revealed that some crucial MIKC genes determined the identities of the five flower organs. Furthermore, the overexpression of in Arabidopsis caused an early flowering phenotype. Meanwhile, the expression levels of the flowering-related genes and were significantly increased in these lines. These results provide useful information for future studies of regulation of cotton flowering.