Skip to main content
. 2003 May;15(5):1159–1169. doi: 10.1105/tpc.009506

Figure 2.

Figure 2.

Effect of Vernalization on the maf2 Mutant.

(A) The maf2 mutant is marginally earlier flowering than wild-type Columbia in the absence of vernalization. Plants are shown after 50 days of growth under a 12-h photoperiod. Water-imbibed seeds were stratified for 3 days at 4°C before transfer to the growth room.

(B) The maf2 mutant is considerably earlier flowering than wild-type Columbia after a short vernalization treatment. Plants are shown after 45 days of growth under a 12-h photoperiod. Imbibed seeds were cold treated for 15 days at 4°C before transfer to the growth room.

(C) The maf2 mutant responds prematurely to vernalization. Data depicted by the graph are available in the supplemental data online. Bars represent days to the appearance of a visible flower bud under a 12-h photoperiod after 4°C cold treatments of 3, 6, 10, 15, 21, and 85 days on imbibed seeds. Error bars indicate standard errors to which 95% confidence limits have been attached. A 10-day cold treatment significantly reduced the time to flowering in the maf2 mutant but not in wild-type Columbia.

(D) Expression of FLC and MAF2 in maf2 and wild-type Columbia seedlings after cold treatments of 3, 6, 10, 15, 21, and 85 days on imbibed seeds. RNA was extracted from pools of 10 whole seedlings after 10 days of growth under 12 h of light, and expression was monitored by RT-PCR over 20, 25, 30, and 35 cycles (products are shown after the following numbers of cycles: FLC, 30; MAF2, 35; and actin, 25). Slashes indicate water controls. The premature vernalization response of maf2 seen in (C) does not seem to be correlated with a premature decline in FLC levels. MAF2 transcript is absent from the maf2 seedlings but is present at a constant level in the 3-, 6-, 10-, 15-, and 21-day time points in the wild type, then declines by the 85-day sample. The MAF2 RT-PCR product is a doublet corresponding to splice variants I and II (see Methods). Equivalent results were obtained when this experiment was repeated for a second time on independent sets of seedlings (data not shown). We also performed RT-PCR with SOC1 primers (data not shown). However, given the fact that SOC1 levels increase very rapidly after germination (Borner et al., 2000; Lee et al., 2000; Michaels and Amasino, 2001), we were unable to detect any differences in SOC1 mRNA levels between the different samples, which were already 13 or more days after germination at the time of harvest.

(E) Summary of the relationship between the duration of cold treatment (days), MAF2/FLC activity, and flowering time for wild-type versus maf2 plants. Twenty-one-day cold-treated maf2 plants flowered equally early as 85-day cold-treated wild-type plants, indicating that the very low levels of MAF2 present in the wild type after the 85-day treatment did not provide significant repression of flowering.