Abstract
Phalaenopsis orchids are globally significant high-value ornamental flowers due to their strange flower shape, gorgeous color, and long flowering period. The successful implementation of reflowering technology is expected to double the economic value of the Phalaenopsis industry. This study selected the cultivated variety Phalaenopsis 'Hatuyuki' as the material to investigate the effects of exogenous gibberellin A(3) (GA(3)) application (0, 50, 100, 150, and 200 mg/L) on its reflowering. Growth phenotype analysis indicates that exogenous GA(3) significantly promotes the occurrence of reflowering in Phalaenopsis 'Hatuyuki' after the first flowering, specifically manifested in elongated leaves, flower bud differentiation, flower stalk growth, and an earlier onset of flowering. The application of exogenous GA(3) significantly enhances the accumulation of starch, soluble sugars, and proteins in Phalaenopsis 'Hatuyuki', while inhibiting the synthesis of free fatty acids. Gibberellins (GA(3), gibberellin A(1) (GA(1)), and gibberellin A(8) (GA(8))), cytokinins (6-Benzyladenosine (BAPR) and Kinetin (K)), and indole-3-acetic acids (IAAs) (tryptamine (TRA), indole-3-acetic acid (IAA)) are the core endogenous hormones responding to exogenous GA(3) spraying treatment. Transcriptome analysis identified a total of 3891 differentially expressed genes (DEGs). The KEGG enrichment analysis revealed that the most significantly enriched KEGG pathways included 'Plant hormone signal transduction'. Key genes involved in the plant hormone signal transduction pathway (AUX, IAA, SAUR, DELLA, MYC2) were validated through qRT-PCR, suggesting that these genes may be crucial for the exogenous GA(3) application that promotes the reflowering of Phalaenopsis 'Hatuyuki'. Additionally, this study highlights 202 core DEGs responsive to exogenous GA(3). Combined with the analysis of hormone signaling pathways, it provides a new perspective for uncovering the key molecular modules involved in GA(3)-regulated reflowering of Phalaenopsis 'Hatuyuki'. Overall, the findings of this study indicate that exogenous GA(3) application can promote the re-flowering of Phalaenopsis 'Hatuyuki'.