Genome editing platform for provitamin a-enriched potato tubers

Overview

This solution uses CRISPR-Cas9 and Cas12a genome editing to increase provitamin A (beta-carotene) content in potato tubers. Standard yellow-fleshed potato varieties contain primarily carotenoids such as lutein, zeaxanthin, and violaxanthin, which lack provitamin A activity, with only trace amounts of beta-carotene. By editing two key genes, the approach aims to convert potato tubers into a meaningful dietary source of vitamin A, addressing deficiency-related conditions such as night blindness in low-income populations, particularly in regions like Africa.

Technical specifications

Editing targets:

• StOr gene: Mutations are introduced at the 3rd exon-intron junction to mimic natural BoOr mutant alleles (originally identified in cauliflower) that trigger chromoplast biogenesis and beta-carotene accumulation. Prior work showed this strategy raised beta-carotene in Desiree tubers from undetectable levels to 5 micrograms per gram dry weight at harvest and up to 17 micrograms per gram dry weight after six months of cold storage.
• StBCH gene(s): Knockout of beta-carotene hydroxylase prevents conversion of beta-carotene into downstream xanthophylls. RNAi-based silencing of one BCH isoform previously increased tuber beta-carotene to 35 micrograms per gram fresh weight.
• Multiplexed editing: Simultaneous targeting of StOr and StBCH to achieve synergistic improvements in beta-carotene accumulation.

Delivery method: Ribonucleoprotein (RNP) complexes of Cas9 or Cas12a with synthetic guide RNAs are delivered into potato protoplasts, enabling DNA-free editing without integration of foreign DNA.

Validation workflow: Mutant plants are regenerated from edited protoplasts, and tuber carotenoid profiles are quantified to assess provitamin A gains.

Technology readiness level

The approach is grounded in published proof-of-concept results from potato, rice, and cauliflower, demonstrating that Or gene variants and BCH suppression each independently increase beta-carotene in storage tissues. Current efforts focus on protoplast transformation, mutant regeneration, and carotenoid profiling. The project is seeking funding support for RNP reagents, mutant generation and screening, analytical work, and partial postdoctoral support, positioning the technology at an early-to-mid stage of translational development toward biofortified potato varieties.