Exploration of the GRAS family in Dimocarpus longan: identification, characterization, expression analysis and DlGRAS24 role in flowering time

Longan is a perennial woody plant, and flowering is crucial for its development and the improvement of its economic value. The GRAS gene family has an important impact on how plants respond to both biotic and abiotic stressors as well as their growth and development. However, current research on the GRAS gene family in longan remains relatively limited. In this study, we identified a total of 56 GRAS gene family members in longan. Phylogenetic analysis revealed that these GRAS members were classified into 14 subfamilies. There are eight tandem duplications and eight segmental duplications in DlGRAS genes, indicating that the expansion of the GRAS family in longan may be driven by tandem duplication and segmental duplication. GRAS family genes showed differential expression patterns of diversity during the flowering process of the “SX” (“Shixia”) and “SJ” (“Sijimi”) varieties, and DlGRAS24 displayed a significant downregulation in ‘SJ’ during the T1-T2 stage. According to a subcellular localization study, DlGRAS24 is located in the nucleus, The DlGRAS24 over-expression Arabidopsis lines exhibited early flowering, and the expression levels of CO and LFY increased, indicating that DlGRAS24 promoted flowering by interacting with CO and LFY. This study conducted a comprehensive analysis of the GRAS gene family members in longan. Our results fill the gap in the identification of the longan GRAS gene family and provide a theoretical basis and reference for the regulation of flowering by the DlGRAS gene family.