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Abstract

The photosynthetic characteristics of four transgenic rice lines over-expressing rice NADP-malic enzyme (ME), and maize phosphoenolpyruvate carboxylase (PC), pyruvate,orthophosphate dikinase (PK), and PC+PK (CK) were investigated using outdoor-grown plants. Relative to untransformed wild-type (WT) rice, PC transgenic rice exhibited high PC activity (25-fold increase) and enhanced activity of carbonic anhydrase (more than two-fold increase), while the activity of ribulose-bisphosphate carboxylase/oxygenase (Rubisco) and its kinetic property were not significantly altered. The PC transgenic plants also showed a higher light intensity for saturation of photosynthesis, higher photosynthetic CO(2) uptake rate and carboxylation efficiency, and slightly reduced CO(2) compensation point. In addition, chlorophyll a fluorescence analysis indicates that PC transgenic plants are more tolerant to photo-oxidative stress, due to a higher capacity to quench excess light energy via photochemical and non-photochemical means. Furthermore, PC and CK transgenic rice produced 22-24% more grains than WT plants. Taken together, these results suggest that expression of maize C(4) photosynthesis enzymes in rice, a C(3) plant, can improve its photosynthetic capacity with enhanced tolerance to photo-oxidation.

Physiological and photosynthetic characteristics of indica Hang2 expressing the sugarcane PEPC gene

“…Compared to non-transformed, wild-type rice, transgenic rice expressing the maize PEPC gene required a higher light intensity to bring about photosynthesis saturation, had a higher photosynthetic CO 2 uptake rate and a higher carboxylation efficiency [33]. The PEPC substrate level (phosphoenolpyruvate) was slightly lower and the reaction product (oxaloacetate) was slightly higher in the transgenic rice, which suggested that the maize PEPC gene was functional in the transgenic rice lines [34].…”

“…Similarly, PEPC and PPDK transgenic rice have been reported to produce 22–24 % more grains than wild-type plants [33]. PEPC transgenic rice had higher dry weights for leaves, stems, sheaths and panicles than the untransformed wild rice, with the largest increase occurring in the panicles.…”

The Pyruvate-Phosphate Dikinase (C4-SmPPDK) Gene From Suaeda monoica Enhances Photosynthesis, Carbon Assimilation, and Abiotic Stress Tolerance in a C3 Plant Under Elevated CO2 Conditions

“…PPDK, involved in C 4 photosynthesis, was more resistant to abiotic stress and elevated CO 2 levels, ameliorating the adverse effects of induced stress. Previously, about a 5-fold increase in PPDK activity was estimated for transgenic lines compared to untransformed controls (Jiao et al, 2002). Enzymes, which are involved in C 4 carbon assimilation, are known to accumulate in leaves under different abiotic stress conditions (Fißlthaler et al, 1995).…”

CO2 Exchange and Chlorophyll Fluorescence of Phospho‐enolpyruvate Carboxylase Transgenic Rice Pollen Lines

“…The genera of Flaveria and Atriplex have been found to have multiple types of photosynthesis, such as C 3 , C 3 -C 4 and C 4 . Moreover, they can cross the species inside the genus so as to transfer C 4 photosynthetic traits into C 3 plants (Rikishi et al 1988;Jiao and Ku 1991;Jiao and Wu 1992;Jiao et al 2002). Rikishi et al (1988) obtained some C 4 -like plants derived from a cross of Atriplex rosea (C 4 )×A.…”

“…The results indicate that PEPC transgenic rice exhibits high levels of PEPC activity, similar to that of maize (Chi et al 2001), an enhanced C 4 photosynthetic property (Chi et al 2001;Huang et al 2002), and has a higher tolerance to photooxidation compared with untransformed rice (Huang and Jiao 2001;Jiao et al , 2002Jiao et al , 2005. Using radioactive isotope methods, it has been proven that a greater amount of CO 2 is fixed in C 4 primary products, presumably indicating control of the primary CO 2 concentrating mechanism (Jiao et al 2003).…”