Figure 5.

Measurement of photosynthetic properties in wild‐type and sig2 mutants grown on soil. Plants were grown at 22°C under white light (100 μmol m⁻² s⁻¹, long‐day condition with 8 hr dark/16 hr light cycle) for 40 days. Undetached leaves from WT (filled circle), sig2‐2 (open circle), sig2‐3 (square), or sig2‐4 (triangle) were used for measurements of distinct photosynthetic properties. (a) Φ_II (photochemical efficiency of PSII) vs. light intensity, (b) NPQ (nonphotochemical quenching) vs. light intensity, (c) maximal quantum yield of PSII (Fv/Fm), (d) LEF (linear electron flow) vs. light intensity, (e) ECS _t (total magnitude of ECS decay) vs. light intensity, (f) $g_{\mathrm{H}}^{+}$ (steady‐state rate of proton flux) vs. light intensity, (g) ECS _t versus pmf _LEF (pmf, generated solely by LEF), (h) CEF (cyclic electron flow) determined from slope of the linear regression of $v_{\mathrm{H}}^{+}$ vs. LEF, and (i) PSI (Φ_I) vs. PSII (Φ_II). Data points in graphs represent mean (±SD, n = 3 individual plants). (a–f) Unpaired, two‐tailed Student's t test comparing sig2 mutants to Col‐0 WT, *p < .05, **p < .005, ***p < .0005, ****p < .00005. (G‐I) Linear regression equations are shown for each plant line