Figure 5. sr45-1 plants are late flowering.

(A) Top panel: sr45-1 plants are considerably later flowering than WT under long-day (LD, 16 h∶8 h light∶dark), short-day (SD, 8 h∶16 h light∶dark) and 12 h∶12 h light∶dark conditions. Age of the plants at the time they were photographed is indicated on each panel. Bottom Panel: Quantification of flowering time. Transition to reproductive stage was measured as days to bolting and number of rosette leaves at the appearance of 1^st flower. Each bar is the mean±SEM of 48 to 72 plants. Significant differences (p<0.05) between WT and sr45-1 plants are indicated by ‘*’. Each experiment was repeated three times. (B) Effect of vernalization on flowering of sr45-1 plants. sr45-1 and WT seeds were stratified at 4°C for 2 days or vernalized for 40 days at 4°C and grown under LD (16 h photoperiod) or SD (8 h photoperiod) conditions in soil. Flowering time was measured as described in experimental procedures. V+and V-indicate vernalized and unvernalized plants, respectively. Significant differences (p<0.05) between vernalized and unvernalized plants are indicated by ‘*’. Each experiment was repeated three times. (C) Expression analyses of flowering related genes in sr45-1 and WT plants. Expression of representative genes in various flowering pathways was analyzed by RT-PCR. VRN2 belongs to the vernalization pathway, FCA to the autonomous pathway; FLC integrates signals from these two pathways. CO belongs to the photoperiod pathway. SOC1 and FT function downstream of FLC. Each RT-PCR was repeated at least three times. (D) Expression levels of various genes in the flowering time pathways of Arabidopsis. Model is adapted from [24], [70]. Value in parentheses next to a gene indicates induction or repression of that gene in sr45-1. NC, No change.