title: Introduction of genes encoding C4 photosynthesis enzymes into rice plants: physiological consequences.
abstract: Transgenic rice plants expressing the maize phosphoeno/pyruvate carboxylase (PEPC) and pyruvate, orthophosphate dikinase (PPDK) exhibit a higher photosynthetic capacity (up to 35%) than untransformed plants. The increased photosynthetic capacity in these plants is mainly associated with an enhanced stomatal conductance and a higher internal CO2 concentration. Plants simultaneously expressing high levels of both enzymes also have a higher photosynthetic capacity. The results suggest that both PEPC and PPDK play a key role in organic acid metabolism in the guard cells to regulate stomatal opening. Under photoinhibitory and photooxidative conditions, PEPC transgenic rice plants are capable of maintaining a higher photosynthetic rate, a higher photosynthetic quantum yield by PSII and a higher capacity to dissipate excess energy photochemically and non-photochemically than untransformed plants. Preliminary data from field trials show that relative to untransformed plants, the grain yield is about 10-20% higher in selected PEPC and 30-35% higher in PPDK transgenic rice plants, due to increased tiller number. Taken together, these results suggest that introduction of C4 photosynthesis enzymes into rice has a good potential to enhance its tolerance to stress, photosynthetic capacity and yield.
authors.affiliation: School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Ku
authors.forename: D
authors.initials: D
authors.lastname: Cho
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: D M
authors.initials: DM
authors.lastname: Jiao
authors.forename: M
authors.initials: M
authors.lastname: Pinto
authors.forename: M
authors.initials: M
authors.lastname: Miyao
authors.forename: M
authors.initials: M
authors.lastname: Matsuoka
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D018014:Gene Transfer Techniques; D012275:Oryza / Q000201:enzymology / Q000235:genetics*; D010730:Phosphoenolpyruvate Carboxylase / Q000235:genetics* / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics* / Q000502:physiology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011772:Pyruvate, Orthophosphate Dikinase / Q000235:genetics* / Q000378:metabolism; D019076:Transgenes
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D002245:Carbon Dioxide; D011772:Pyruvate, Orthophosphate Dikinase; D010730:Phosphoenolpyruvate Carboxylase