Figure 4.

Effects of Vernalization on the Expression of MAF2 to MAF5 in Different Genetic Backgrounds.

RNA was extracted from pools of 10 to 20 8-day-old seedlings grown under continuous light conditions. Expression was monitored by RT-PCR over 20, 25, 30, and 35 cycles for each of the genes. Products are shown after 30 cycles (FLC and MAF1 to MAF5) and 25 cycles (actin). Vernalized (+) samples were cold treated for 6 weeks at 4°C, whereas nonvernalized (−) samples were stratified for only 3 days at 4°C as imbibed seeds. Note that FLC levels are lower in vernalized than in nonvernalized samples, confirming the efficacy of the treatment. MAF2 levels are similar between vernalized and nonvernalized seedlings from all backgrounds. MAF3 and MAF4 levels are lower in vernalized than in nonvernalized samples for each of the different backgrounds. MAF5 levels, however, in contrast to FLC levels, are higher in vernalized compared with nonvernalized samples for each of the different backgrounds. Equivalent expression patterns were obtained for each of the genes when the experiment was repeated for a second time on different batches of seedlings that were vernalized and grown independently of those represented here. The upregulation of MAF5 by vernalization also was confirmed in two additional independent experiments performed on wild-type Columbia seedlings (data not shown). Col, Columbia; Pi-0, Pitztal; St-0, Stockholm; fca, fca-9 mutant.