Metabolic Engineering to Enhance Provitamin D3 Accumulation in Edible Tomatoes

Abstract

Ensuring adequate levels of vitamin D3 in the human diet has long been an important objective in crop breeding, as most crops have extremely low levels of this compound. To address this challenge, we have employed the CRISPR-Cas9 gene editing system in tomatoes to induce loss-of-function mutations in one of the two DWARF5 genes, a homologue of the human dehydrocholesterol Δ7-reductase gene. Lines with knocked out SIDWF5A gene exhibited visually undistinguishable phenotypes, yet remarkably accumulated provitamin D3 levels as high as 6 μg/g dry weight (DW) in the red fruits. As the daily recommended intake of vitamin D is 20 μg (800 IU), consuming a single ripe fresh tomato weighing 150 g (equivalent to 15 g DW) has the potential to significantly alleviate widespread vitamin D deficiencies worldwide.