Over the past few years, three photorespiratory bypasses have been introduced into plants, two of which led to observable in creases in photos yn thesis and biomass yield. However, most of the experiments were carried...Over the past few years, three photorespiratory bypasses have been introduced into plants, two of which led to observable in creases in photos yn thesis and biomass yield. However, most of the experiments were carried out using Arabidopsis under controlled environmental conditions, and the increases were only observed under low-light and short-day conditions. In this study, we designed a new photorespiratory bypass (called GOC bypass), characterized by no reducing equivalents being produced during a complete oxidation of glycolate into CO2 catalyzed by three rice-self-originating enzymes, i.e., glycolate oxidase, oxalate oxidase, and catalase. We successfully established this bypass in rice chloroplasts using a multi-gene assembly and transformation system. Transgenic rice plants carrying GOC bypass (GOC plants) showed significant increases in photosynthesis efficiency, biomass yield, and nitrogen content, as well as several other CO2-enriched phe no types under both greenhouse and field conditions .Grain yield of GOC plants varied depending on seeding season and was increased significantly in the spring. We further demonstrated that GOC plants had significant advantages under high-light conditions and that the improvements in GOC plants resulted primarily from a photosynthetic CO2-concentrating effect rather than from improved energy balance. Taken together, our results reveal that engineering a newly designed chloroplastic photorespiratory bypass could increase photosynthetic efficiency and yield of rice plants grown in field conditions, particularly under high light.展开更多
Several photorespiratory bypasses have been introduced into plants and shown to improve photosynthesis by increasing chloroplastic C02 concentrations or optimizing energy balance.We recently reported that an engineere...Several photorespiratory bypasses have been introduced into plants and shown to improve photosynthesis by increasing chloroplastic C02 concentrations or optimizing energy balance.We recently reported that an engineered GOC bypass could increase photosynthesis and productivity in rice.However,the grain yield of GOC plants was unstable,fluctuating in different cultivation seasons because of varying seed setting rates.In this study,we designed a synthetic photorespiratory shortcut(the GCGT bypass)consisting of genes en-coding Oryza sativa glycolate oxidase and Escherichia coli catalase,glyoxylate carboligase,and tartronic semialdehyde reductase.The GCGT bypass was guided by an optimized chloroplast transit peptide that targeted rice chloroplasts and redirected 75% of carbon from glycolate metabolism to the Calvin cycle,identical to the native photorespiration pathway.GCGT transgenic plants exhibited significantly increased biomass production and grain yield,which were mainly attributed to enhanced photosynthesis due to increased chloroplastic C02 concentrations.Despite the increases in biomass production and grain yield,GCGT transgenic plants showed a reduced seed setting rate,a phenotype previously reported for the GOC plants.Integrative transcriptomic,physiological,and biochemical assays revealed that photosynthetic car-bohydrates were not transported to grains in an efficient manner,thereby reducing the seed setting rate.Taken together,our results demonstrate that the GCGT photorespiratory shortcut confers higher yield by promoting photosynthesis in rice,mainly through increasing chloroplastic C02 concentrations.展开更多
基金the National Natural Science Foundation of China (31470343, 31770256)the Science and Technology Project of Guangzhou City (201607020006).
文摘Over the past few years, three photorespiratory bypasses have been introduced into plants, two of which led to observable in creases in photos yn thesis and biomass yield. However, most of the experiments were carried out using Arabidopsis under controlled environmental conditions, and the increases were only observed under low-light and short-day conditions. In this study, we designed a new photorespiratory bypass (called GOC bypass), characterized by no reducing equivalents being produced during a complete oxidation of glycolate into CO2 catalyzed by three rice-self-originating enzymes, i.e., glycolate oxidase, oxalate oxidase, and catalase. We successfully established this bypass in rice chloroplasts using a multi-gene assembly and transformation system. Transgenic rice plants carrying GOC bypass (GOC plants) showed significant increases in photosynthesis efficiency, biomass yield, and nitrogen content, as well as several other CO2-enriched phe no types under both greenhouse and field conditions .Grain yield of GOC plants varied depending on seeding season and was increased significantly in the spring. We further demonstrated that GOC plants had significant advantages under high-light conditions and that the improvements in GOC plants resulted primarily from a photosynthetic CO2-concentrating effect rather than from improved energy balance. Taken together, our results reveal that engineering a newly designed chloroplastic photorespiratory bypass could increase photosynthetic efficiency and yield of rice plants grown in field conditions, particularly under high light.
基金Major Program of Guangdong Basic and Applied Research(2019B030302006)the National Key Research and Development Program(2020YFA0907600),China.
文摘Several photorespiratory bypasses have been introduced into plants and shown to improve photosynthesis by increasing chloroplastic C02 concentrations or optimizing energy balance.We recently reported that an engineered GOC bypass could increase photosynthesis and productivity in rice.However,the grain yield of GOC plants was unstable,fluctuating in different cultivation seasons because of varying seed setting rates.In this study,we designed a synthetic photorespiratory shortcut(the GCGT bypass)consisting of genes en-coding Oryza sativa glycolate oxidase and Escherichia coli catalase,glyoxylate carboligase,and tartronic semialdehyde reductase.The GCGT bypass was guided by an optimized chloroplast transit peptide that targeted rice chloroplasts and redirected 75% of carbon from glycolate metabolism to the Calvin cycle,identical to the native photorespiration pathway.GCGT transgenic plants exhibited significantly increased biomass production and grain yield,which were mainly attributed to enhanced photosynthesis due to increased chloroplastic C02 concentrations.Despite the increases in biomass production and grain yield,GCGT transgenic plants showed a reduced seed setting rate,a phenotype previously reported for the GOC plants.Integrative transcriptomic,physiological,and biochemical assays revealed that photosynthetic car-bohydrates were not transported to grains in an efficient manner,thereby reducing the seed setting rate.Taken together,our results demonstrate that the GCGT photorespiratory shortcut confers higher yield by promoting photosynthesis in rice,mainly through increasing chloroplastic C02 concentrations.
