A synthetic light-inducible photorespiratory bypass enhances photosynthesis to improve rice growth and grain yield

Bioengineering of photorespiratory bypasses is an effective strategy for improving plant productivity by modulating photosynthesis.In previouswork,two photorespiratory bypasses,theGOC andGCGT bypasses,increased photosynthetic rates but decreased seed-setting rate in rice(Oryza sativa),probably owing to excess photosynthate accumulation in the stem.To solve this bottleneck,we successfully developed a newsynthetic photorespiratory bypass(called theGMAbypass)in rice chloroplasts by introducing Oryza sativa glycolate oxidase 1(OsGLO1),Cucurbita maxima malate synthase(CmMS),and Oryza sativa ascorbate peroxidase7(OsAPX7)into the rice genome using a high-efficiency transgene stacking system.Unlike the GOC and GCGT bypass genes driven by constitutive promoters,OsGLO1 in GMA plants was driven by a light-inducible Rubisco small subunit promoter(pRbcS);its expression dynamically changed in response to light,producing a more moderate increase in photosynthate.Photosynthetic rates were significantly increased inGMA plants,and grain yieldswere significantly improved under greenhouse and field conditions.Transgenic GMA rice showed no reduction in seed-setting rate under either test condition,unlike previous photorespiratory-bypass rice,probably reflecting proper modulation of the photorespiratory bypass.Together,these results imply that appropriate engineering of the GMA bypass can enhance rice growth and grain yield without affecting seed-setting rate.

Improving photosynthetic efficiency toward food security:Strategies,advances,and perspectives

Photosynthesis in crops and natural vegetation allows light energy to be converted into chemical energy and thus forms the foundation for almost all terrestrial trophic networks on Earth.The efficiency of photosynthetic energy conversion plays a crucial role in determining the portion of incident solar radiation that can be used to generate plant biomass throughout a growth season.Consequently,alongside the factors such as resource availability,crop management,crop selection,maintenance costs,and intrinsic yield potential,photosynthetic energy use efficiency significantly influences crop yield.Photosynthetic efficiency is relevant to sustainability and food security because it affects water use efficiency,nutrient use efficiency,and land use efficiency.This review focuses specifically on the potential for improvements in photosynthetic efficiency to drive a sustainable increase in crop yields.We discuss bypassing photorespiration,enhancing light use efficiency,harnessing natural variation in photosynthetic parameters for breeding purposes,and adopting new-to-nature approaches that show promise for achieving unprecedented gains in photosynthetic efficiency.