**5. Conclusions**

Bioinformatics analyses of 50 B3 genes in grapevine revealed that gene duplication played a role in the expansion of the B3 family in grapes. It was also found that B3 genes from grapevine and Arabidopsis shared some common ancestor. Studies of phylogeny, gene structure, and conserved motifs of the B3 genes have further provided insights on the evolutionary history of the grapevine B3 genes. Taken together, these results underscore the potential importance for B3 genes grapevine growth and development, particularly for seed development. Therefore, our systematic study of these genes will help in identifying candidate genes for functional studies. It will also serve as a foundation and reference for future research regarding the molecular mechanisms controlling the seedlessness trait of grapes.

**Supplementary Materials:** Supplementary materials can be found at http://www.mdpi.com/1422-0067/20/18/4553/ s1. Data Figure S1. Conserved motifs analysis of grape B3 proteins according to the phylogenetic relationship. Box length corresponds to motif length. Each motif is represented by a number in a colored box. Table S1. Tandem duplication events in grapevine B3 genes. Table S2. Synteny blocks of B3 genes within grape genomes Table S3. Synteny blocks of B3 genes between grape and Arabidopsis Table S4. Segmental duplication pairs of B3 genes between grape and tomato. Table S5. Primer sequences used in expression analysis of B3 genes in grape. Table S6. Expression values of 25 grape B3 genes during different stages of ovule development in semiquantitative PCR. Red Globe is represented by 'RG' and Thompson Seedless is represented by 'TS'. Table S7. Expression values of 25 grape B3 genes in different plant organs in semiquantitative PCR. Red Globe is represented by 'RG' and Thompson Seedless is represented by 'TS'.

**Author Contributions:** X.W., B.A., and S.Z. designed the experiments. B.A. and S.Z. conducted the experiments. M.H. helped in RT-PCR. X.W. and M.U.R. supplied materials/analyses. X.W. provided guidance throughout the study. J.Y. and Y.Z. helped in bioinformatics work. B.A. and X.W. wrote the manuscript. All authors approved the final manuscript.

**Funding:** This study was supported by the National Natural Science Foundation of China (U1603234), the Program for Innovative Research Team of Grape Germplasm Resources and Breeding (2013KCT-25), and the Fundamental Research Funds for the Central Universities (2452019170).

**Conflicts of Interest:** The authors declare no conflicts of interest.
