Genome editing: first application for drought tolerance
PROJECT TITLE: Genome editing: first application for drought tolerance
Project leader: Johan Burger (Stellenbosch University)
Contact: jtb@sun.ac.za
Duration: 1 February 2021 – 31 December 2023
Problem identification and project objectives:
Given the negative economic impact of biotic and abiotic stresses on the international viticulture industry, a multitude of research projects have increasingly focused on these issues. In South Africa, abiotic stresses to agricultural crops are largely ascribed to drought, such as recently experienced in the Western Cape. Long-term forecasts of climate patterns suggest that droughts are likely to recur. Drought is a complex trait and not easy to manipulate for tolerance, especially in a woody perennial like grapevine.
Recently a precise and quick technology for targeted mutagenesis or genome editing named CRISPR/Cas was developed and has since been implemented in various crops. This project aims to build on the experience we acquired in CRISPR/Cas technology over the last three years. During this time, we illustrated an ability to design and introduce CRISPR/Cas constructs targeting genes in the carotenoid pathway of both N..benthamiana and grapevine, resulting in a characteristic albino phenotype for both species. We now propose to expand our experience with CRISPR-based applications in abiotic (drought) tolerance in grapevine. This gene editing approach forms part of the initiative to generate new and more resistant plant materials and complement traditional grapevine breeding programme approaches. The technology is also gaining international acceptance, with genome editing now being considered as significantly different from traditional GM technology in a number of European countries.
For the proposed project we would like to provide proof-of-principle for the gene editing approach towards the commercially important problem of drought sensitivity. Plants under drought stress accumulate the signalling hormone abscisic acid (ABA), which in turn is responsible for the rapid closure of stomata, thereby preventing water loss. This process is under transcriptional control of a MYB family of proteins. Recently, researchers in Italy (Galbiati et al., 2011) discovered and characterised VvMYB60, a grapevine transcription factor with high similarity to AtMYB60, an Arabidopsis guard cell-related drought-responsive gene. In collaboration with two Italian groups, we propose to target this gene in the grapevine genome using our established CRISPR technology. Our role would be to design the CRISPR constructs, and to assemble these at Stellenbosch University (SU), while the transformation and regeneration of the chosen table grape cultivar(s) (Sugraone at this stage) will be done at Fondazione Edmund Mach (FEM) in Italy. Phenotypic and molecular analysis of the mutant lines will be conducted jointly by SU and FEM. This editing event could provide the chosen cultivar an improved ability to modulate water content and increased water use efficiency.