F-box genes: Genome-wide expansion, evolution and their contribution to pollen growth in pear (Pyrus bretschneideri).

F-box gene family, as one of the largest gene families in plants, plays crucial roles in regulating plant development, reproduction, cellular protein degradation and responses to biotic and abiotic stresses. However, comprehensive analysis of the F-box gene family in pear (Pyrus bretschneideri Rehd.) and other Rosaceae species has not been reported yet. Herein, we identified a total of 226 full-length F-box genes in pear for the first time. And these genes were further divided into various subgroups based on specific domains and phylogenetic analysis. Intriguingly, we observed that whole-genome duplication and dispersed duplication have a major contribution to F-box family expansion. Furthermore, the dynamic evolution for different modes of gene duplication was dissected. Interestingly, we found that dispersed and tandem duplicate have been evolving at a high rate. In addition, we found that F-box genes exhibited functional specificity based on GO analysis, and most of the F-box genes were significantly enriched in the protein binding (GO: 0005515) term, supporting that F-box genes might play a critical role for gene regulation in pear. Transcriptome and digital expression profiles revealed that F-box genes are involved in the development of multiple pear tissues. Overall, these results will set stage for elaborating the biological role of F-box genes in pear and other plants.