Chloroplast gene-editing platform for enhancing crop heat tolerance via psba 5'UTR modification

Overview

This solution leverages a proprietary chloroplast gene-editing platform to enhance crop heat tolerance by modifying the 5' untranslated region (5'UTR) of the psbA gene. The psbA gene encodes the D1 protein, a critical component of the photosynthetic machinery that undergoes rapid turnover, especially under heat stress. Currently, only about 25% of psbA mRNA is translated, limiting the availability of functional D1 protein to replace damaged copies during high-temperature conditions. By introducing single nucleotide polymorphisms (SNPs) into the psbA 5'UTR, translation efficiency can be upregulated, resulting in improved photosynthetic performance and heat resilience. Because the editing occurs in the chloroplast genome, edited alleles are maternally inherited, making the resulting plants ideal as maternal breeding lines for developing heat-tolerant crop varieties.

Technical specifications

Editing platform capabilities:

• A proprietary gene construct enables random base substitutions within a targeted 25-35 bp region of the chloroplast genome
• Mutations are rapidly fixed in regenerated plants through a proprietary selection scheme
• A single transgenic line can be used to generate more than five distinct alleles of a target chloroplast gene
• The construct is delivered via nuclear transformation, allowing it to be easily crossed out to produce transgene-free plants

Biological approach:

• Targets the highly conserved psbA 5'UTR to modulate D1 protein translation efficiency
• Produces transgene-free edited plants suitable as maternal germplasm lines
• Applicable to crops including tobacco (proof-of-concept model), sugarbeet, cassava, and broad bean

Proof-of-concept plan:

• Generate a tobacco line enabling isolation of multiple psbA 5'UTR alleles
• Analyze over 50 edited plants confirmed by Sanger sequencing
• Evaluate psbA expression levels and heat tolerance phenotypes

Technology readiness level

The chloroplast gene-editing system has been validated for generating multiple alleles of selected chloroplast genes using a single transgenic line. The psbA 5'UTR editing approach is currently at the proof-of-concept stage, with tobacco selected as the initial model for demonstrating heat tolerance improvements. Given the high conservation of the psbA 5'UTR across plant species, successful results in tobacco are expected to be transferable to other crops. Patents for the editing system are held by the developing organization, supporting potential licensing and co-development pathways.