Genome-wide characterization and expression profiling of B3 superfamily during ethylene-induced flowering in pineapple (Ananas comosus L.)

Background The B3 superfamily (B3s) represents a class of large plant-specific transcription factors, which play diverse roles in plant growth and development process including flowering induction. However, identification and functional surveys of B3 superfamily have not been reported in ethylene-induced pineapple flowering (Ananas comosus). Results 57 B3 genes containing B3 domain were identified and phylogenetically classified into five subfamilies. Chromosomal localization analysis revealed that 54 of 57 AcB3s were located on 21 Linkage Groups (LG). Collinearity analysis demonstrated that the segmental duplication was the main event in the evolution of B3 gene superfamily, and most of them were under purifying selection. The analysis of cis-element composition suggested that most of these genes may have function in response to abscisic acid, ethylene, MeJA, light, and abiotic stress. qRT-PCR analysis of 40 AcB3s containing ethylene responsive elements exhibited that the expression levels of 35 genes were up-regulated within 1 d after ethephon treatment and some were highly expressed in flower bud differentiation period in stem apex, such as Aco012003, Aco019552 and Aco014401. Conclusion This study provides a basic information of AcB3s and clues for involvement of some AcB3s in ethylene-induced flowering in pineapple.

Automated summary

The study identified 57 B3 genes in pineapple, classified into five subfamilies. The genes may play roles in response to abscisic acid, ethylene, MeJA, light, and abiotic stress. The expression levels of 35 genes were up-regulated in response to ethylene induction, indicating their potential involvement in pineapple flowering.