Components of the Arabidopsis CBF Cold-Response Pathway Are Conserved in Non-heading Chinese Cabbage

Abstract

Many plants increase in freezing tolerance upon exposure to low non-freezing temperatures, a phenomenon known as cold acclimation. Cold acclimation in Arabidopsis involves rapid cold-induced expression of the inducer of C-repeat/dehydration-responsive element-binding factor (CBF) expression (ICE) transcriptional activators followed by expression of the CBF; subsequently, CBF-targeted genes that increase freezing tolerance. Here, we present evidence for a CBF cold-response pathway in non-heading Chinese cabbage (Brassica campestris ssp. chinensis L. Makino). We show that non-heading Chinese cabbage encodes ICE1-like gene BrICE1 that bracket an open reading frame of 1,491 bp encoding a protein with a potential bHLH domain, which accumulates rapidly in response to low temperature followed closely by expression of the BrCBF gene, an ortholog of the Arabidopsis CBF3-like gene, and then BrCOR14 gene, an ortholog of the Arabidopsis CBF-targeted COR15b gene. An alignment of the later two genes from Arabidopsis, Brassica napus revealed the presence of conserved CANNTG core element and AP2 domain in BrCBF and a CCG core element in BrCOR14. In addition, BrCBF and BrCOR14 showed increased expression induced by low temperature as well as salt and drought, but not by ABA stress which are similar to those of Arabidopsis. We conclude that components of the CBF cold-response pathway are highly conserved in non-heading Chinese cabbage.