What can cold-induced transcriptomes of Arctic Brassicaceae tell us about the evolution of cold tolerance?

Little is known about the evolution of cold tolerance in polar plant
species and how they differ from temperate relatives. To gain insight into
their biology and the evolution of cold tolerance, we compared the
molecular basis of cold response in three Arctic Brassicaceae species. We
conducted a comparative time series experiment to examine transcriptional
responses to low temperature. RNA was sampled at 22 °C, and after 3h, 6h,
and 24h at 2 °C. We then identified sets of genes that were differentially
expressed in response to cold and compared them between species, as well
as to published data from the temperate Arabidopsis thaliana. Most
differentially expressed genes were species-specific, but a significant
portion of the cold response was also shared among species. Among
thousands of differentially expressed genes, ~200 were shared among the
three Arctic species and A. thaliana, while ~100 were exclusively shared
among the three Arctic species. Our results show that cold response
differs markedly between Arctic Brassicaceae species, but likely builds on
a conserved basis found across the family. They also confirm that highly
polygenic traits such as cold tolerance may show little repeatability in
their patterns of adaptation.