Investigation of a cellular chloroplast compartment's regulator using genetics and advanced imaging, seeking improved agronomic performance.

The project is fully within the remit of BBSRC, its priority area "Bioscience for sustainable agriculture and food". It aims to eventually translate Arabidopsis genetic research into a crop. It emerges from a Royal Holloway (RHUL) PhD thesis whose examiners noted: "the work identifies information with tremendous possible beneficial uses in agriculture".

A mutation in the SGL1 gene was identified at RHUL as part of a search for global regulators of chloroplast development. As the sites of photosynthesis, chloroplasts generate (convert) all the biological energy provided by crops to humanity. Leaf mesophyll cells, contrary to other cell types, have a very large

proportion of cellular space allocated to chloroplasts, How this is achieved is barely understood. Two transcription factors, GLK1 and GLK2, substantially mediate the expression of photosynthesis-associated nuclear genes in land plants. In search for mechanisms, the RHUL lab mutagenised an Arabidopsis glk1

glk2 mutant, a pale plant with numerous but underdeveloped chloroplasts and reduced greening, to identify suppressors. A mutation named suppressor of glks 1 resulted in a dramatic suppression phenotype. It enhanced leaf development and overall plant growth in a wild type GLK1 GLK2 background. It also delayed

the flowering time in long photoperiods, which in some crops is not desirable, something this project will address. There is a clear need to identify knock out gene targets for enhancing yield because there is strong demand for higher yielding crops and, unlike other approaches, knock out strategies can be delivered using gene

editing technologies. Gene edits are increasingly not subject to restrictive GMO regulations, which increases the likelihood of ultimately developing a product that reaches farmers and has impact increasing food production. This project seeks to build on this research to inform a novel gene editing approach for

enhancing crop yields sustainably.