Genome-Wide Characterization of <i>MADS-box</i> Genes Identifies Candidates Associated with Flower and Fruit Development in Loquat (<i>Eriobotrya japonica</i> Lindl.)

The MADS-box transcription factors have garnered substantial attention due to their crucial involvement in various biological processes, particularly in flower organogenesis. A comprehensive investigation into the MADS-box genes remains lacking in loquat (Eriobotrya japonica Lindl.). In the current study, to preliminarily explore the potential candidate genes related to flower and fruit development, a genome-wide analysis was carried out to identify and characterize the MADS-box gene family in loquat. Among the 125 identified EjMADS-box members, 49 genes belonged to type Ⅰ, which were subsequently assigned to three subfamilies: Mα (25 genes), Mβ (10 genes), and Mγ (14 genes). Additionally, 76 genes fell under type II, which were categorized into two groups: MIKCC (70 genes) and MIKC* (6 genes). Through the collinearity analysis and comparison of the gene numbers between loquat and other Rosaceae genomes, it was revealed that the type Ⅱ MADS-box members were expanded in Maloideae after a whole genome duplication. The gene expression analysis utilizing various tissues during flower development revealed that the expression patterns of the ABCDE model homologs were conserved in loquat. In addition, several candidate genes potentially involved in flower bud differentiation (EjMADS107/109) and fruit expansion (EjMADS24/46/49/55/61/67/77/86) were identified. This analysis could serve as a fundamental basis for investigating the molecular functions of the MADS-box genes in the development of flowers as well as fruits in loquat