The Basis of Freezing Tolerance Between and Within Species Across Environmental Gradients with a Focus on Arctic, Alpine and Moorland Plants

Abstract

Freezing events have devastating impacts on crops around the world. Climate change is resulting in more extreme freezing events as well as an increase in winter warm periods and shorter winters which can alter the process of acclimation and deacclimation leading to greater freezing susceptibility. Genes involved in freezing tolerance therefore need to be targeted by crop breeders to improve crop resistance to these events. The CBF family is one of these potential targets due to their presence across the Spermatophyta, including crop species, and their role in acclimation as transcription factors which activate cold response (COR) genes, thereby increasing freezing tolerance. Plants adapted to environments with frequent and very low temperature freezing events, such as arctic and alpine locations may, therefore, already possess modifications to these genes which improve freezing tolerance. The ability of native, dominant cover species to endure and adapt to these climatic changes can also be investigated via the study of variation within CBF over a species range.
CBF sequences were isolated from numerous arctic and alpine species. Several common polymorphisms in key CBF regions were identified and applied to Arabidopsis thaliana CBF1. The effect upon freezing tolerance and CRT/DRE activation of these modified A. thaliana CBF1 sequences were then tested. No definitive conclusions could be drawn, however potential routes of further investigation are highlighted and discussed.
CBF sequences of Empetrum nigrum samples from a wide distribution and both high and low altitude were compared, no differences between sequences which correlated with sample location, were found. However preliminary expression studies indicated a difference in the kinetics of CBF expression between samples from different locations. Further study of CBF expression kinetics within this species is highly recommended.
Routes of further exploration leading to potential targets for crops are discussed, alongside suggested routes of further investigation for Empetrum nigrum and Calluna vulgaris.