Table I. Pigment contents and photosynthetic parameters in the wild-type and nfu3 mutant plants.
Chlorophyll and carotenoid were extracted and determined as described by Wellburn (1994). Measurements of chlorophyll fluorescence parameters were performed on dark-adapted plants with the IMAGING-PAM M-series chlorophyll fluorescence system (Heinz Waltz). For photochemical quenching (qP), the redox state of the PSII acceptor side (1-qP), nonphotochemical quenching (NPQ), energy-dependent quenching (qE), and photoinhibitory quenching (qI) measurements, an actinic light treatment (531 μmol photons m−2 s−1) was performed for 715 s. After the termination of actinic light, recovery of the maximal fluorescence of light-adapted leaves was monitored for 14 min. Measurements of P700 photooxidation were performed on dark-adapted, detached leaves with the Dual-PAM-100 measuring system (Heinz Waltz). Far-red light-induced P700 oxidation (ΔA830m) is calculated as the absorbance change before and after a 25-s illumination of saturating far-red light (720 nm). Data are presented as means ± se (n = 5 for pigment contents, n = 4 for chlorophyll fluorescence parameters, and n = 6–9 for P700 photooxidation). Asterisks indicate significant differences between the mutant and the wild type (Student’s t test: *, P < 0.05; **, P < 0.01; and ***, P < 0.001).
| Parameter | Wild Type | nfu3-1 | nfu3-2 |
|---|---|---|---|
| Chlorophyll a (mg g−1 fresh wt) | 1.353 ± 0.069 | 1.092 ± 0.035* | 1.058 ± 0.023** |
| Chlorophyll b (mg g−1 fresh wt) | 0.337 ± 0.022 | 0.276 ± 0.014 | 0.278 ± 0.009 |
| Total chlorophyll (mg g−1 fresh wt) | 1.689 ± 0.090 | 1.368 ± 0.049* | 1.337 ± 0.032* |
| Chlorophyll a/b | 4.031 ± 0.067 | 3.971 ± 0.108 | 3.807 ± 0.046* |
| Carotenoid (mg g−1 fresh wt) | 0.402 ± 0.015 | 0.371 ± 0.013 | 0.359 ± 0.008* |
| Maximum photochemical efficiency of PSII (Fv/Fm) | 0.828 ± 0.006 | 0.722 ± 0.006*** | 0.723 ± 0.005*** |
| qP | 0.555 ± 0.024 | 0.088 ± 0.035*** | 0.063 ± 0.009*** |
| 1-qP | 0.445 ± 0.024 | 0.912 ± 0.035*** | 0.937 ± 0.009*** |
| NPQ | 2.375 ± 0.105 | 3.174 ± 0.072** | 2.924 ± 0.094** |
| qE | 1.942 ± 0.095 | 2.750 ± 0.053*** | 2.496 ± 0.084** |
| qI | 0.434 ± 0.012 | 0.424 ± 0.035 | 0.428 ± 0.019 |
| ΔA830m (relative units) | 0.444 ± 0.021 | 0.027 ± 0.004*** | 0.026 ± 0.008*** |