Figure 6.

UV-B-induced lipase up-regulation. Wild-type Arabidopsis plants (3.5 weeks old) were treated for up to 4 consecutive days with UV-B. The daily treatment consisted of 16 h of exposure to photosynthetically active radiation plus UV-B followed by 8 h of darkness. Cumulative hours of actual exposure to UV-B and the days on which it occurred are indicated. A, Northern blot of total RNA isolated from rosette leaves after various periods of UV-B exposure. The blot was probed with the 3′ untranslated region of the lipase cDNA. Each lane contained 10 μg of RNA. B, Corresponding ethidium bromide-stained agarose gel of the fractionated RNA.