Abstract
When grown under cool temperature, winter annuals upregulate
photosynthetic capacity as well as freezing tolerance. Here, the role of
three cold-induced C-repeat-Binding Factor (CBF1–3) transcription
factors in photosynthetic upregulation and freezing tolerance was
examined in two Arabidopsis thaliana ecotypes originating from
Italy (IT) or Sweden (SW), and their corresponding CBF1–3-deficient
mutant lines it:cbf123 and sw:cbf123 . Photosynthetic,
morphological, and freezing-tolerance phenotypes as well as gene
expression profiles were characterized in plants grown from seedling
stage under different combinations of light level and temperature. Under
high light and cool growth temperature (HLC), a greater role of CBF1–3
in IT versus SW was evident from both phenotypic and transcriptomic
data, especially with respect to photosynthetic upregulation and
freezing tolerance of whole plants. Overall, features of SW were
consistent with a different approach to HLC acclimation than seen in IT,
and an ability of SW to reach the new homeostasis through involvement of
transcriptional controls other than CBF1–3. These results provide tools
and direction for further mechanistic analysis of the transcriptional
control of approaches to cold acclimation suitable for either
persistence through brief cold spells or for maximization of
productivity in environments with continuous low temperatures.