FIGURE 2.

ALA pretreatment increases flavonols accumulation in guard cells. Two-week-old wild-type (WT) Arabidopsis pretreated with exogenous 0.5 mg L^-1 ALA under light (240 μmol m^-2 s^-1) for 4 h and YHem1-transgenic Arabidopsis incubated under the same light condition for 4 h were loaded with 2.52 mg mL^-1 diphenylboric acid 2-aminoethyl ester (DPBA) for 30 min in darkness at 25°C. The cotyledons were then picked with tweezers and their fluorescence (A) was observed using a confocal microscope. For each treatment, DPBA bound to flavonols is shown in yellow and chlorophyll autofluorescence is shown in blue in separate channels. Scale bar: 15 μm. (B) DPBA intensity values in guard cells of each treatment. Values are the means of 15 measurements ± SE from three independent experiments. ^∗∗ indicates significant differences between treatments at P = 0.01 level.