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: