Lycopene Is Enriched in Tomato Fruit by CRISPR/Cas9-Mediated Multiplex Genome Editing

TLDR

Tomato breeding has focused on increasing lycopene to improve fruit visual and functional qualities. The study aimed to boost lycopene accumulation by enhancing its biosynthesis while suppressing its conversion to β‑ and α‑carotene. The authors knocked down carotenoid‑pathway genes and used CRISPR/Cas9 delivered by Agrobacterium tumefaciens to edit five target genes. CRISPR/Cas9 editing raised lycopene about 5.1‑fold, produced stable homozygous mutations, and demonstrated high efficiency, low off‑target effects, and heritable changes.

Abstract

Numerous studies have been focusing on breeding tomato plants with enhanced lycopene accumulation, considering its positive effects of fruits on the visual and functional properties. In this study, we used a bidirectional strategy: promoting the biosynthesis of lycopene, while inhibiting the conversion from lycopene to β- and α-carotene. The accumulation of lycopene was promoted by knocking down some genes associated with the carotenoid metabolic pathway. Finally, five genes were selected to be edited in genome by CRISPR/Cas9 system using Agrobacterium tumefaciens-mediated transformation. Our findings indicated that CRISPR/Cas9 is a site-specific genome editing technology that allows highly efficient target mutagenesis in multiple genes of interest. Surprisingly, the lycopene content in tomato fruit subjected to genome editing was successfully increased to about 5.1-fold. The homozygous mutations were stably transmitted to subsequent generations. Taken together, our results suggest that CRISPR/Cas9 system can be used for significantly improving lycopene content in tomato fruit with advantages such as high efficiency, rare off-target mutations, and stable heredity.