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. 2009 Jan;149(1):205–219. doi: 10.1104/pp.108.125005

Figure 9.

Figure 9.

Expression of ra1, ra2, and ra3 in Sos1 mutants and model for the role of sos1 in SPM determinacy. A to C, Real-time RT-PCR experiments showing the relative expression level of (A) ra1, (B) ra2, and (C) ra3 in Sos/+ and Sos/Sos1 mutants. C, Model for the interaction between Sos1 and the ramosa genes. ra1, ra2, and ra3 are required to promote SPM determinacy. We propose that Sos1 is a negative regulator of SPM determinacy. ra2 and ra3 act upstream of ra1 as well as having roles independent of ra1. As Sos1; ra1 double mutants resemble Sos1 single mutants, sos1 is placed downstream of ra1. As Sos1; ra2 double mutants have an enhanced phenotype similar to ra1; ra2 double mutants, sos1 is proposed to positively regulate ra1. Sos1; ra3 double mutants have an additive phenotype, indicating that ra3 acts in an independent pathway. The model is supported by expression studies showing that ra1 is reduced, but ra2 and ra3 are unchanged in Sos1 mutants.