CRISPR/Cas9-mediated dual editing of VviGAI and VviFLC generates a novel early-flowering grapevine germplasm.

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conclusionCRISPR/Cas9-mediated dual knockout of VviGAI1 and VviFLC in grapevine promotes early flowering and induces distinctive morphological changes, offering novel genetic resources for breeding. CRISPR/Cas9-mediated genome editing offers a transformative approach for grapevine improvement. In this study, we achieved simultaneous knockout of two central flowering regulators VviGAI1, a DELLA protein ortholog, and VviFLC, a floral repressor in Vitis vinifera 'Cabernet Sauvignon' using a dual-sgRNA vector system. Remarkably, all 15 independent edited lines exhibited biallelic mutations in both genes, primarily consisting of frameshifts that led to premature termination. The dual-mutant plants displayed a range of distinctive phenotypic alterations, including dwarfism, shortened internodes, modified leaf morphology, and disrupted tendril development. Notably, one line (EL-43) showed precocious flowering under greenhouse conditions, underscoring the synergistic role of VviGAI1 and VviFLC in repressing floral transition. Comparative analysis with previously reported gai mutants revealed both conserved and novel traits, suggesting that structural variation within the DELLA domain contributes to phenotypic diversity. Collectively, our findings establish that dual editing of VviGAI1 and VviFLC not only accelerates flowering but also introduces unique vegetative and reproductive characteristics, providing a valuable genetic resource for future grapevine domestication and precision breeding efforts.