Figure 6.

RNA gel-blot analysis of PnCO transcripts probed with the long intron or the intron-less PnCO(ni) cDNA. Five-day-old light-grown seedlings were transferred to the light-dark regimes shown on the bar graphs. Cotyledons were harvested at the end of each dark period. Poly(A)⁺ RNA preparations were analyzed by RNA gel blotting. Actin mRNA served as loading control. The blot was probed with the long intron and with the intron-free, full-length cDNA clone PnCO(ni). Plants that had been kept in uninterrupted darkness for 14 h developed six or seven flower buds after 1 month in continuous light. Plants that had received 8 h of darkness or 14 h of darkness with a night break after 8 h remained vegetative.