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 GRAS (DlGRAS) genes in the longan genome and conducted a comprehensive bioinformatics analysis of these genes. RNA-seq analysis revealed that the expression of these DlGRAS genes differed during early SE and across various longan tissues. The quantitative real-time PCR (qRT-PCR) results indicated that the DlGRAS 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 DlGRAS12/15 decreased significantly. In contrast, exogenous ABA promoted the expression of DlGRAS6/10/23, indicating that DlGRAS genes are responsive to hormones. Compared with CaMV35S-driven GUS expression, the promoters of DlGRAS10/22 increased GUS expression, GA3 and ABA treatments enhanced promoter activity. DlGRAS10/22 were located in the nucleus. Overexpression of DlGRAS10/22 in longan SE significantly promoted the transcription levels of SE-related genes, including DlGID1, DlGA20ox2, DlLEC1, DlFUS3, DlABI3 and DlLEC2. Therefore, DlGRAS may be involved in the early morphogenesis of longan SE through the hormone signaling pathway.