Identification of Chinese cabbage genes up-regulated by prolonged cold by using microarray analysis

Vernalization is induced by prolonged cold and accelerates flowering. To monitor the genome-wide transcriptome change that identifies the genes that are differently up-regulated depending on the duration of cold exposure, we fabricated a Chinese cabbage cDNA microarray and used it to identify genes that are up-regulated by short-term (1-week) and long-term (4-week) cold. The overall expression patterns between 1- and 4-week cold treated seedlings were very similar but some genes in the cell growth/division/DNA synthesis functional category were regulated differently. Prolonged cold specifically up-regulated several heat shock proteins ( HSPs), and small HSPs were more significant. Among the up-regulated sHSPs, we chose the small HSP 17.6-II and confirmed its up-regulation in response to long- but not short-term cold exposure by Northern analysis. And its constitutive overexpression moderately accelerated flowering.