Date of this Version
Plant Physiology Preview. Published on May 27, 2016, as DOI:10.1104/pp.16.00286
Low temperature is a seasonal abiotic stress which restricts native plant ranges and crop distributions. Two types of low temperature stress can be distinguished: chilling and freezing. Much work has been done on the mechanisms by which chilling is sensed, but relatively little is known about how plants sense freezing. Recently, SENSITIVE TO FREEZING 2 (SFR2) was identified as a protein which responds in a non-transcriptional manner to freezing. Here, we investigate the cellular conditions which allow SFR2 activation. Using a combination of isolated organelle, whole tissue and whole plant assays, we provide evidence that SFR2 is activated by changes in cytosolic pH and Mg2+. Manipulation of pH and Mg2+ in cold acclimated plants is shown to cause changes similar to those of freezing. We conclude that pH and Mg2+ are perceived as intracellular cues as part of the sensing mechanism for freezing conditions. This evidence provides a specific molecular mechanism to combat freezing.