Fig. 4. Cotyledon fusion in double mutants between stm-2 and syd-2 or atbrm-1. (A) In stm-2, cotyledon fusion is negligible and the formation of one to two leaves (yellow arrowhead) can be observed at 10 days after germination (Clark et al., 1996). (B) Strong cotyledon fusion (petiole and base of cotyledons) was observed in stm-2 atbrm-1. (C) stm-1 exhibits only partial fusion of the cotyledon petiole (Barton and Poethig, 1993). (D) In stm-2 syd-2, cotyledon fusions are variable and range from frequent partial petiole fusion (red arrowhead) to stronger cotyledon fusions (heart shaped seedlings) (Kwon et al., 2005). Pictures were taken 10 days after germination. Scale bars: 2 mm. Genotype is indicated in each image. The outermost border of each fusion event is indicated by red arrowheads. (E) Real-time PCR evaluation of CUC message levels in single versus double mutants using biological duplicates. After normalizing with the message levels of the ubiquitously expressed translation initiation factor EIF4A, the resulting values for stm-2 were set to one to facilitate comparison between the lines. (F) Real-time PCR of ANT, FIL and UFO. The RNA analyzed was as in E. Shown are the mean and the s.e.m. of triplicate reactions normalized as in E. (G) Real-time PCR of CUC2 performed on RNA isolated from single mutant or wild-type inflorescences. Shown are the mean and s.e.m. of triplicate reactions normalized as in E.