Beyond freezing tolerance: CBF regulon genes involved in HLC
acclimation
Six IT-specific CBF regulon genes under HLC were confirmed by RT-qPCR
(Fig. 10). Putative IT-specific CBF regulon genes under HLC were
selected by two criteria, i.e., (i) as having been defined as a
CBF-target gene in prior work (Park et al., 2018) and (ii)showing strong induction under HLC in IT. From among 31 genes that
satisfied both criteria, nine were selected for validation by RT-qPCR
with priority given to genes with protein domains or linked to a role in
photosynthetic or leaf-morphological acclimation phenotypes. Genes
confirmed as IT-specific CBF regulon genes under HLC, i.e., attenuated
in it:cbf123 relative to IT but unchanged in sw:cbf123relative to SW, included sucrose synthase SUS1 (AT5G20830),
growth regulator EGR2 (AT5G27930), and four strongly
HLC-induced genes in both ecotypes with no known functions, includingRCI2A (AT3G05880), AT5G44565, AT1G13930, andLCR69 (AT2G02100). Three of the nine candidate genes tested for
IT-specific CBF regulation had significantly lower expression in thecbf 123 mutants of not only IT but also SW relative to
their respective parental ecotype under HLC and are thus not IT-specific
CBF regulon genes under HLC (Fig. S2).
iv. c. Discussion: