Genome-wide identification of the ABCB gene family in melon (Cucumis melo L.) and their expression during axillary bud development

Introduction Melon ( Cucumis melo L.) is an important economic crop, yet its cultivation relies heavily on manual pruning to regulate branching, which limits melon industrialization. Branching originates from axillary bud development, a process regulated by polar auxin transport, in which ABCB proteins serve as key auxin transporters. However, systematic identification of the ABCB gene family in melon and the functional roles of its members in axillary bud development have not been systematically elucidated. Methods We performed a genome-wide identification of the ABCB gene family from the latest melon genome using bioinformatics approaches. We systematically analyzed the physicochemical properties and other characteristics of the identified CmABCB genes. Additionally, RNA sequencing (RNA-seq) and qRT-PCR were employed to investigate the expression patterns of these genes in axillary buds under IAA treatment. Results Through this genome-wide identification, we identified a total of 39 CmABCB genes in the melon genome. Phylogenetic analysis classified them into five subgroups, with Group I being unique to melon. Collinearity analysis revealed a close evolutionary relationship between melon and cucumber. Expression profiling revealed that several genes responded specifically to IAA treatment. Notably, CmABCB14 , CmABCB20 , and CmABCB21 exhibited a statistically significant positive correlation between their expression levels and IAA concentration. Discussion Collectively, these findings suggest that CmABCB14 , CmABCB20 , and CmABCB21 may function as auxin efflux carriers that suppress axillary bud growth. This study therefore provides a theoretical basis for understanding the molecular mechanisms underlying branching regulation in melon and offers a valuable framework for the precise improvement of plant architecture and the reduction of production costs through molecular breeding.