CRISPR/Cas9-mediated editing of 1-aminocyclopropane-1-carboxylate oxidase1 enhances Petunia flower longevity

The genes that encode the ethylene biosynthesis enzyme 1-aminocyclopropane-1-carboxylate oxidase (ACO) are thought to be involved in flower senescence. Hence, we investigated whether the transcript levels of PhACO genes (PhACO1, PhACO3 and PhACO4) in Petunia cv. Mirage Rose are associated with ethylene production at different flowering stages. High transcript levels were detected in the late flowering stage and linked to high ethylene levels. PhACO1 was subsequently edited using the CRISPR/Cas9 system, and its role in ethylene production was investigated. PhACO1-edited T-0 mutant lines, regardless of mutant type (homozygous or monoallelic), exhibited significantly reduced ethylene production and enhanced flower longevity compared with wild-type. Flower longevity and the reduction in ethylene production were observed to be stronger in homozygous plants than in their monoallelic counterparts. Additionally, the transmission of the edited gene to the T-1 (lines 6 and 36) generation was also confirmed, with the results for flower longevity and ethylene production proving to be identical to those of the T-0 mutant lines. Overall, this study increases the understanding of the role of PhACO1 in petunia flower longevity and also points to the CRISPR/Cas9 system being a powerful tool in the improvement of floricultural quality.