Fig. 3. Spatial and temporal expression of AtSWC6. (A) Northern blot analysis of AtSWC6 expression in different Arabidopsis tissues. RNA was extracted from 20-day-old Col grown in long-day conditions for whole plants (Wh), root (Rt), shoot apex (SA) and rosette leaves (RL). RNA for old leaves (OL), stem (St) and inflorescence with flowers (Inf) was extracted from 40-day-old plants. (B) Temporal expression of AtSWC6 assessed by RT-PCR. RNA was extracted from 5-, 8-, 11- and 14-day-old Col grown in long-day conditions. All the samples were harvested 4 hours after light on. (C) Diurnal rhythm of AtSWC6 expression assessed by RT-PCR. RNA was extracted from 10-day-old Col grown in long-day conditions. Northern blot analysis with the same RNA showed diurnal rhythm in SUF3 expression. (D) The effect of photoperiod and vernalization on AtSWC6 expression. FRI with (+) and without (-) vernalization, and Col grown under long-day (LD) and short-day (SD) conditions were used for northern blot and RT-PCR analyses. For RT-PCR analysis, TUB expression served as an internal control. (E) Spatial expression patterns of AtSWC6 were examined by GUS staining in the AtSWC6p-AtSWC6:GUS transgenic plant. Histochemical GUS staining was performed in whole (a) 3-, (b) 5- and (c) 10-day-old plants, in (d) inflorescence and flowers, (e) an axillary bud, (f,g) developing seeds and (g) siliques of different stages.