Impact of cbf deficiency on photosynthesis and leaf morphology in SW and IT under HLC
The impact of the cbf123 mutation on photosynthetic and leaf-morphological traits was ecotype-specific under HLC. Strikingly, the sw:cbf123 null mutant exhibited no significant differences under HLC in photosynthetic capacity, chlorophyll a + bper unit area, dry leaf mass per unit area, leaf thickness, or rosette diameter relative to SW (Fig. 7-9, Table 2). In contrast, the it:cbf123 mutant in HLC showed modestly, but significantly, lower levels of these five traits relative to IT. Photosynthetic capacity (Fig. 7a) was 27% lower in HLC plants of it:cbf123 relative to IT and leaf thickness (Fig. 8b-e) was 32% lower (Fig. 8a), withp- values of 0.0043 and 0.0042, respectively. Dry leaf mass per unit area and chlorophyll a + b levels per unit area were also modestly lower in it:cbf123 relative to IT in HLC, withp -values of 0.000021 and 0.0082, respectively (Fig. 7b,c). Differences in photosynthetic capacity, dry mass per leaf area, and chlorophyll a + b levels per unit area between it:cbf123 and its parental ecotype were specific to HLC and not observed under LLW (Fig. 7). Another trait altered by the cbf123mutation in HLC plants of lT but not of SW was rosette diameter that was significantly larger in it:cbf123 versus IT under HLC (Fig. 9 & Fig. S1). Lastly, there were no significant differences between thecbf mutants relative to their parental ecotypes in QA redox state (data not shown) or chlorophylla/b ratio (Fig. 7d) under the growth and measurement regimes tested.