FloResEng - Engineering endogenous oxygen sensing for improved flood resilience in cereals

• Applicants: Dr. Jozefus Hendrikus Maria Schippers; Professorin Dr. Romy Schmidt-Schippers
• Subject Area: Plant Physiology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 552975616

Flooding is a major cause of crop yield loss that has increased globally with climate change. To secure global food supplies as well as farmers’ incomes, it is important to improve crop, particularly cereal resilience to flooding. One way to achieve this is tuning the plant’s endogenous response to flooding. Previously, it was identified how plants respond at the molecular level to reduced oxygen (O2) availability (hypoxia) during submergence. Flood acclimation genes are controlled by Group VII ethylene response transcription factors (ERFVIIs) stabilised by hypoxic conditions. Plant Cysteine Oxidases (PCOs) are conserved enzymes that sense endogenous O2 levels and promote ERFVII degradation before and after a flood. Our high-resolution structural analyses of PCOs have identified a tunnel controlling the rate at which O2 is delivered to the active site. Tunnel engineering in Arabidopsis PCOs alters their O2 sensitivity and is a route to modulate ERFVII stabilisation and improve flood resilience. PCO structures are highly conserved in crops and other plants; we can now apply enzyme engineering to crop PCOs. Our targets are the key staple cereals barley and rice. Barley is highly intolerant of waterlogged soil, while rice is "the" model crop for flood resilience. Combined study of these crops will be advantageous. This project integrates and leverages our combined expertise in hypoxia signalling and responses, plant gene editing, and advancement of flood-resilient crops to the field. We will engineer PCOs to modulate ERFVII stabilisation to improve flood resilience in barley and rice. To do so, our engineering strategy is applied to endogenous PCOs of both species. PCO gene variation will be exploited from pangenomes of rice/barley accessions, combined with our structure-function knowledge, to identify 'naturally-occuring' PCO forms with altered O2 kinetics. We will use our in-vitro biochemical methods to validate altered O2 sensitivity in a targeted set of rice/barley PCOs. Our pipeline will direct successful variants to in vivo testing and implementation using complementary strategies balancing risk and outcome, including protoplast transformation and gene editing. Ultimately, we will examine the impact of our PCO tunnel variants in greenhouse and field-scale studies of barley/rice. Success is determined through quantitative analysis of molecular impacts on low-O2 signaling, physiological analysis of flood resilience and phenotypic impacts on grain productivity. Overall, FloResGen will tune PCO activity to improve resilience to transient flooding in crops. By combining biochemistry, molecular genetics, plant physiology and targeted protein engineering we will help to pinpoint molecular traits to fine-tune crop adaptation to flooding stress relevant to the current climate crisis. We will deliver: (i) flood-resilient barley and rice varieties ready for large field-scale trials and (ii) a mechanism to engineer climate resilience in other crops.

• DFG Programme: Research Grants
• International Connection: United Kingdom, USA
• Partner Organisation: Biotechnology und Biological Sciences Research Council (BBSRC); National Science Foundation (NSF)
• Cooperation Partners: Professorin Julia Bailey-Serres, Ph.D.; Professorin Dr. Emily Flashman