Journal Article

Synthetic glycolate metabolism pathways stimulate crop growth and productivity in the field

Cavanagh, Amanda P., Ort, Donald R., South, Paul F., Liu, Helen W.

2019

Overview

In some of our most useful crops (such as rice and wheat), photosynthesis produces toxic by-products that reduce its efficiency. Photorespiration deals with these by-products, converting them into metabolically useful components, but at the cost of energy lost. South et al. constructed a metabolic pathway in transgenic tobacco plants that more efficiently recaptures the unproductive by-products of photosynthesis with less energy lost (see the Perspective by Eisenhut and Weber). In field trials, these transgenic tobacco plants were ∼40% more productive than wild-type tobacco plants. Science , this issue p. eaat9077 ; see also p. 32 Tobacco plants carrying engineered glycolate metabolic pathways showed as much as 40% greater productivity than wild-type plants in field trials. Photorespiration is required in C 3 plants to metabolize toxic glycolate formed when ribulose-1,5-bisphosphate carboxylase-oxygenase oxygenates rather than carboxylates ribulose-1,5-bisphosphate. Depending on growing temperatures, photorespiration can reduce yields by 20 to 50% in C 3 crops. Inspired by earlier work, we installed into tobacco chloroplasts synthetic glycolate metabolic pathways that are thought to be more efficient than the native pathway. Flux through the synthetic pathways was maximized by inhibiting glycolate export from the chloroplast. The synthetic pathways tested improved photosynthetic quantum yield by 20%. Numerous homozygous transgenic lines increased biomass productivity between 19 and 37% in replicated field trials. These results show that engineering alternative glycolate metabolic pathways into crop chloroplasts while inhibiting glycolate export into the native pathway can drive increases in C 3 crop yield under agricultural field conditions.

• Publisher: American Association for the Advancement of Science,The American Association for the Advancement of Science
• Subject: Agricultural economics / Agricultural land / Agricultural production / Algae / Aquatic plants / Biomass / Byproducts / Carbon dioxide / Carbon Dioxide - metabolism / Carboxylates / Carboxylation / Catalase / Chlamydomonas reinhardtii - enzymology / Chloroplasts / Chloroplasts - metabolism / Construction costs / Crop growth / Crop production / Crop yield / Crops / Crops, Agricultural - growth & development / Crops, Agricultural - metabolism / Cucurbita - enzymology / E coli / Efficiency / Escherichia coli / Escherichia coli - enzymology / Farm buildings / Field Tests / Flowers & plants / Gene expression / Gene Expression Regulation, Plant / Genes / Genes, Bacterial / Glycolate dehydrogenase / Glycolates - metabolism / Grain / Grain crops / Greenhouses / Growing season / Human populations / Life cycles / Malate synthase / Metabolic engineering / Metabolic Networks and Pathways - genetics / Metabolic pathways / Metabolism / Metabolites / Nicotiana - growth & development / Nicotiana - metabolism / Oxidation / Oxygenase / Photorespiration / Photosynthesis / Plant Science / Plants, Genetically Modified - growth & development / Plants, Genetically Modified - metabolism / Productivity / Proteins / RESEARCH ARTICLE SUMMARY / Ribonucleic acid / Ribulose-1,5-bisphosphate / Ribulose-bisphosphate carboxylase / Ribulose-Bisphosphate Carboxylase - metabolism / Ribulosephosphates - metabolism / Rice / RNA / RNA Interference / RNA-mediated interference / Screens / Soybeans / Stress, Physiological / Synthetic Biology / Temperature / Tobacco / Tobacco industry / Transgenic plants / Wheat