Delivering novel maize genotypes with improved resilience and PROductivity through the application of predictive breeding technologies to modulate STRIGolactone levels
PROSTRIG employs novel breeding technologies, specifically precise Genome Editing using CRISPR/cas9 technology to create maize (corn) varieties with higher productivity while simultaneously minimizing environmental impact directly because the novel maize varieties will require much less application of nitrogen and phosphorus fertilizers. Modulation of the plant hormones strigolactones provides this opportunity. A novel approach using tunable modulation of two carotenoid cleavage dioxygenase enzymes (CCD7 and CCD8) specifically involved in the biosynthesis of these compounds can modulate strigolactone content and composition and will potentially result in a complete new root architecture simultaneously encouraging stimulation of hyphal branching in fungal symbionts that form arbuscular mycorrhizae. Consequently, less fertilizer will be required due to the improved uptake efficiency of nitrogen and phosphorus as a result of this symbiosis. These properties will enable greater crop intensification in a highly sustainable manner thus delivering the paramount objective of the SUSCROP call in a manner entirely congruent with the call for proposals. A further direct impact is the generation of novel phenotypes which can be commercialized directly as these do not fall under GMO regulations at least outside the EU. The recent decision of the EU court to subject GE crops to GMO regulations complicates their commercialization in Europe and will further exacerbate the division between the EU and the rest of the world in terms of trade and implementation of the international GATT agreement (General Agreement on Tariffs and Trade). In this context a further direct impact of PROSTRIG is to provide experimental evidence and outputs in the form of scientific and white papers, and popular articles in the press to explain why GE crops should not be treated as GMOs on a purely scientific basis. The current status of the project is as follows: ZmCCD7/8 promoter target sites have been identified. Expression vector for SaCas9 is cloned and validated. rSaCas9 activity on target sites are established by in vitro assays. Molecular methods are established for screening edited maize plants. The project carried out very limited maize transformation experiments, yet was able to recover a number of plants with SaCas9 and both gRNAs (targeting CCD7 and CD8 gene promoters simultaneously). Identified maize plants with only SaCas9 are very useful as this provides an alternative strategy to recover mutations through breeding. A metabolomic pipeline has been established to evaluate transgenic maize plants. Data integration capability and the project website are set up. The project will establish a technology platform which will be open to all EU companies interested in taking advantage of the potential commercial outcomes of the project in terms of knowhow, technology, IP and tangible outputs including experimental data, safety and efficacy data from animal feeding trials, optimized expression vectors, germplasm and lead plant lines characterized fully also under field conditions, all complemented by a full Life Cycle Assessment and a comprehensive Techno-economic Analysis. PROSTRIG contributes directly to European competitiveness because it focuses on a major industrial European and global food security crop, important as a commercial product and also as a relevant biological system to answer fundamental questions in development, physiology, genetics and metabolism.
Prof Paul Christou
University of Lleida, SPAIN
Prof Paul Fraser
Royal Holloway University of London, United Kingdom
Prof Stefan Schillberg
Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Germany
Giron-Calva, P. S., Perez-Fons, L., Sandmann, G., Fraser, P. D., & Christou, P. (2021). Nitrogen inputs influence vegetative metabolism in maize engineered with a seed-specific carotenoid pathway. Plant Cell Reports, 40(5), 899-911.
Project webpage: http://prostrig.udl.cat/