Table II.
Physiological characteristics in plants grown at 20°C or 30°C
CO2 assimilation rate at 1,500 μmol photons m−2 s−1 and 380 μL L−1 CO2 concentration (A380), the Rubisco activation state, the NADP-MDH activation state, and in vivo catalytic turnover rate of Rubisco were analyzed. The catalytic turnover rate of Rubisco was calculated from gross CO2 assimilation rates (A380 + dark respiration) and Rubisco carbamylated site contents. Dark respiration was measured after a 10-h dark period. Different letters show significant differences (Tukey-Kramer multiple comparison test; P < 0.05).
| Characteristic | 25°C |
40°C |
||||
|---|---|---|---|---|---|---|
| Wild Type | Intermediate | Low | Wild Type | Intermediate | Low | |
| 20°C-grown plants | ||||||
| A380 (μmol CO2 m−2 s−1) | 19.3 ± 0.3 a | 17.7 ± 0.5 a | 8.00 ± 0.95 b | 16.7 ± 0.5 a | 12.0 ± 0.76 b | 2.36 ± 0.99 c |
| Rubisco activation (%) | 81.2 ± 0.4 a | 75.9 ± 2.3 a | 55.3 ± 3.3 b | 64.0 ± 0.6 a | 51.2 ± 2.2 b | 37.9 ± 2.2 c |
| NADP-MDH activation (%) | 51.5 ± 3.9 a | 49.9 ± 2.0 a | 50.5 ± 2.6 a | 23.7 ± 1.7 a | 26.5 ± 1.2 a | 26.7 ± 0.8 a |
| In vivo catalytic turnover rate of Rubisco (s−1) | 0.949 ± 0.055 a | 0.986 ± 0.038 a | 0.656 ± 0.084 b | 1.23 ± 0.08 a | 1.29 ± 0.09 a | 0.737 ± 0.158 b |
| 30°C-grown plants | ||||||
| A380 (μmol CO2 m−2 s−1) | 16.0 ± 0.4 a | 15.8 ± 0.3 a | 8.56 ± 1.77 b | 15.1 ± 0.4 a | 12.6 ± 0.6 a | 3.92 ± 1.25 b |
| Rubisco activation (%) | 75.8 ± 0.5 a | 70.9 ± 2.0 a | 50.0 ± 2.7 b | 62.3 ± 0.7 a | 53.2 ± 1.7 b | 37.5 ± 1.9 c |
| NADP-MDH activation (%) | 61.0 ± 3.6 a | 62.8 ± 2.9 a | 59.5 ± 1.0 a | 38.0 ± 3.4 a | 41.2 ± 2.1 a | 37.2 ± 0.9 a |
| In vivo catalytic turnover rate of Rubisco (s−1) | 1.11 ± 0.07 a | 1.20 ± 0.10 a | 0.849 ± 0.121 b | 1.55 ± 0.10 a | 1.60 ± 0.08 a | 1.00 ± 0.13 b |