Genome-Wide Identification of DlGRAS Family and Functional Analysis of DlGRAS10/22 Reveal Their Potential Roles in Embryogenesis and Hormones Responses in Dimocarpus longan

GRAS family plays a critical role in plant growth and stress responses. In this study, we identified 47 <i>GRAS</i> (<i>DlGRAS</i>) genes in the longan genome and conducted a comprehensive bioinformatics analysis of these genes. RNA-seq analysis revealed that the expression of these <i>DlGRAS</i> genes differed during early SE and across various longan tissues. The quantitative real-time PCR (qRT-PCR) results indicated that the <i>DlGRAS</i> genes exhibited differential expression during the early SE of longan, with most of them showing high expression at the globular embryo (GE) stage. Under GA₃ treatment, the transcript levels of <i>DlGRAS12/15</i> decreased significantly. In contrast, exogenous ABA promoted the expression of <i>DlGRAS6/10</i>/<i>23</i>, indicating that <i>DlGRAS</i> genes are responsive to hormones. Compared with CaMV35S-driven <i>GUS</i> expression, the promoters of <i>DlGRAS10/22</i> increased <i>GUS</i> expression, GA₃ and ABA treatments enhanced promoter activity. DlGRAS10/22 were located in the nucleus. Overexpression of <i>DlGRAS10/22</i> in longan SE significantly promoted the transcription levels of SE-related genes, including <i>DlGID1</i>, <i>DlGA20ox2</i>, <i>DlLEC1</i>, <i>DlFUS3</i>, <i>DlABI3</i> and <i>DlLEC2</i>. Therefore, <i>DlGRAS</i> may be involved in the early morphogenesis of longan SE through the hormone signaling pathway.