Comprehensive analysis of CYP78A family genes reveals the involvement of <i>CYP78A5</i> and <i>CYP78A10</i> in fruit development in eggplant

CYP78A family is a plant-specific family, members of which have been considered as promising targets for yield improvement due to their important roles in regulating organ size. Eggplant is an important vegetable cultivated worldwide. However, little information about the eggplant CYP78As (SmCYP78As) limits the potential utilization of SmCYP78As for crop improvement. In this study, we identified six CYP78A genes in eggplant genome and named SmCYP78A5 to SmCYP78A10 according to the phylogenetic relationships to Arabidopsis CYP78As. The phylogenetic analysis of CYP78As from eggplant, Arabidopsis, rice and tomato classified the 27 CYP78As into five clades. SmCYP78As were found in three of the five clades. This classification is consistently supported by their gene structures, domains and conserved motifs. Segmental duplication events were found to contribute the expansion of the SmCYP78A family. Comparative syntenic analysis provided further insight into the phylogenetic relationships of CYP78A genes from the four plants. qRT-PCR analysis revealed that the expression of the six SmCYP78As was detected in at least one of the eight tissues, showing a tissue-specific pattern. Notably, SmCYP78A5 and SmCYP78A10 were highly expressed in developing ovaries, indicating the involvement of fruit development in eggplant. Co-expression clustering and GO enrichment analysis suggested that SmCYP78A5 and SmCYP78A10 regulate fruit development likely through different pathways. In addition, six transcription factors were identified as promising candidates that may directly bind promoters of SmCYP78A5 and SmCYP78A10. This study provides a comprehensive overview of the SmCYP78As family, which would lay a foundation for further understanding of evolution and function of SmCYP78A family.