Comparative genomic analysis of the RabGAP gene family in seven Rosaceae species, and functional identification of PbrRabGAP10 in controlling pollen tube growth by mediating cellulose deposition in pear

Abstract

Rab GTPase-activating proteins (RabGAPs), serving as crucial signaling switches, play essential roles in several physiological processes related to plant growth and development. However, despite their importance, information regarding the RabGAP gene family and their biological functions remains unknown in the Rosaceae. In this study, we identified a total of 127 RabGAP genes in seven Rosaceae species, which were divided into five subfamilies. Our findings indicate that whole genome duplication (WGD) events or dispersed duplication events largely contributed to the expansion of RabGAP family members within Rosaceae species. Through tissue-specific expression analyses, we revealed that the PbrRabGAP genes exhibited distinct expression patterns in different pear tissues. Furthermore, by examining the expression pattern during pollen development and employing an antisense oligonucleotide approach, we demonstrated that PbrRabGAP10, located in the cytoplasm, mediates the imbalance of cellulose distribution, thus regulating pollen tube elongation. In conclusion, the present study offers an overview of the RabGAP family in Rosaceae genomes and serves as the basis for further functional studies.

Keywords: Cellulose; Evolution; Expression profile; Pollen tube growth; Rab GTPase-activating protein.