Genome-wide identification of the MADS-box gene family and their role in the formation of faba bean (Vicia faba L.) growth habits.

BACKGROUND: The MADS-box gene family is important in florescence development and flower organ formation. Members can directly or indirectly influence leguminous crops growth habits. However, this gene family in faba bean (Vicia faba L.) and its role in the development of various growth habits have not been systematically reported. RESULTS: We identify 82 VfMADS genes in faba bean. Phylogenetic relationships, gene structure, conserved motifs, and expression patterns in varieties with different growth habits are investigated. Of them, 41 VfMADS proteins are classified as Type II and are attributed to 11 subfamilies. We report 12 pairs of tandem duplication events in VfMADS genes that involve 26 genes. Cis-acting elements in promoter regions suggest that these genes are involved mainly with hormone and stress responses. A new type of semi-determinate growth habit is reported for faba bean and transcriptome sequencing reveals 56 MADS-box genes to be differentially expressed in accessions with 3 types of growth habits. Significant differences are reported for expression levels of 10 VfMADS genes in different growth habits and tissues, indicating that VfMADS genes are closely related to floral transition, especially the floral termination at the shoot apex. CONCLUSIONS: We systematically identify MADS-box genes in faba bean and investigate their physicochemical properties, phylogenetic relationships, chromosomal distribution, conserved motifs, cis-acting elements and expression patterns in faba bean with different growth habits. By doing so, we improve understanding of the regulatory network of growth habits and provide a theoretical basis for future studies on the functional characteristics of VfMADS genes in faba bean.