4.2.2 ⎪ Stronger enrichment in IT compared to SW under HLC
The well-characterized phenotypic features of cold acclimation do occur in IT, but to a lesser extent than in SW. It is noteworthy that the genes more strongly induced under HLC in IT compared to SW have been implicated in abiotic stress responses, as was reported for chloroplast glucose-6 phosphate/phosphate translocator GPT2 (Dyson et al. 2015), chloroplast envelope K+/H+antiporter KEA2 (Kunz et al. 2014), light-harvesting complexLHCB4.3 (Klimmek, Sjödin, Noutsos, Leister & Jansson 2006), cytosolic phosphofructokinase (Kant et al. 2008), cytosolic fumarase (Pracharoenwattana et al. 2010), ferritins (Petit, Briat & Lobréaux 2001), and pyridoxal phosphate synthase (Denslow, Rueschhoff & Daub 2007). Future research should further test the hypothesis that both SW and IT make acclimatory adjustments that limit oxidative stress under HLC conditions, but that changes in SW focus more on enhancement of productivity (which also lowers excitation pressure more effectively), while IT undergoes alternative evasive changes that are somewhat less effective in controlling excitation pressure.
Moreover, genes exhibiting greater down-regulation in HLC in IT compared to SW were those involved in growth hormone transport and signaling (cytokinin-activated, auxin polar transport, and response to auxin). As stated above, such effects could be related to the hormonal control of vascular acclimation.