Protein import is vital for chloroplast functioning

Plastids, including chloroplasts, are specialised organelles found within plant cells. The development and functioning of plastids are dependent on the import of thousands of proteins, carried out by TOC proteins located in the outer membrane and TIC proteins located in the inner membrane. The CHLORAD pathway influences plastid development by interacting with TIC/TOC proteins to modify protein import and degradation.

Impact of CHLORAD pathway manipulation

Stabilisation of TOC proteins, triggered through inactivation of the CHLORAD SP2 gene, results in alternations to plastid development. This can be applied to induce a “stay-green” phenotype by delaying the conversion of chloroplasts into gerontoplasts, another type of plastid. Cereals exhibiting the “stay-green” phenotype show an increased grain yield due to an extended photosynthetic period, and an additional benefit is a reduction in the development of pathogens that develop at the end of the growing season.

Mutants overexpressing CHLORAD proteins also demonstrated an improved response to abiotic stress tolerance. This could be applied in crop species to reduce yield losses in response to abiotic stresses.

The CHLORAD pathway could also be targeted to influence fruit ripening. It has been demonstrated in tomato that fruit ripening can be accelerated through an increase in the expression level of CHLORAD pathway genes causing a depletion of TOC proteins. Alternatively, fruit ripening could be delayed by inhibiting protein activity.

Market opportunities

The technology would be utilised in the creation of unique seed products with improved traits. Current estimates for the size of the global seed market range between $50-60 billion. According to Mordor Intelligence, this market is expected to increase with a CAGR of 7.1 % to 2022.

The gene-editing market is demonstrating high levels of growth, expected to grow at a CAGR of 51.2% to 2022. In crops where GM approaches have not been adopted, such as wheat, gene editing represents a clear market opportunity.