show Abstracthide AbstractThe two Arabidopsis ecotypes that are adapted to Italy and Sweden, respectively, showed different degree of freezing tolerance. By comparing the low temperature transcriptomes of the IT and SW ecotypes with the CBF pathway being knocked out, we showed the CBF pathway plays a significant role in natural variation of freezing tolerance. Overall design: Examination of mRNA levels in cbf CRISPR mutants in background of the Arabidospsis Italian and Swedish ecotype plants grown at warm, cold for 24h, and cold for 2 weeks.