A synthetic glycolate metabolism bypass in rice chloroplasts increases photosynthesis and yield

Photorespiration consumes photosynthetically fixed carbon and reduces yields by 20%–50% in C₃ crops. In an attempt to increase photosynthetic efficiency in rice by bypassing the carbon-consuming process of photorespiration, a photorespiratory bypass consisting of Chlamydomonas reinhardtii glycolate dehydrogenase and Cucurbita maxima malate synthase (termed the GMS bypass) was introduced into the rice cultivar Zhonghua 11 and osplgg1b, a mutant of the rice chloroplast glycolate transporter, to generate GMS/ZH11 and GMS/osplgg1b transgenic plants. The GMS bypass reduced photorespiration and increased photosynthesis in the transgenic plants. The straw biomass of GMS/ZH11 and GMS/osplgg1b increased by up to 16.0% and 85.7%, respectively. The yield of GMS/ZH11 increased by 22.0%–34.7% in paddy fields. Thus, the GMS bypass can increase photosynthetic efficiency and yield in rice.