Fig. 4. Interactions of RPL with BP and AS1. (A,B) Cross sections of stage 13 gynoecia from wild-type and 35S::BP Arabidopsis plants, showing GUS staining from the BLR::GUS transgene, a reporter of RPL. (A) GUS staining is restricted to the replum in the wild type. (B) GUS is detected throughout the ovary, including valves and valve margins, in 35S::BP gynoecia. (C,D) GUS staining from the BLR::GUS transgene in rosettes. In the wild-type background (C), staining is detected in the meristem (hidden by the leaves in the picture), whereas the signal is ectopically seen in cotyledons and leaves of plants that overexpress BP (D). (E,F) Cross sections of stage 17 fruits from several mutants harboring rpl alleles. Fruits from rpl-1 (E) and rpl-2 (F) show narrow repla containing cells that adopt a valve margin identity. (G) The replumless phenotype is even stronger in the bp-9 rpl-2 double mutant. (H-J) The as1-1 allele rescues the replumless phenotype conferred by rpl alleles. The wild-type phenotype is observed in as1-1 rpl-2 (H) and as1-1 rpl-1 (I) fruits. (J) A moderate replumless phenotype is observed in an as1-1 rpl-1 fruit. (K,L) SEMs of stage 17 fruits showing the replumless phenotype of rpl-2 (K) and the wild-type phenotype of an as1-1 rpl-2 fruit (L). The genetic background is ER, with the exception of E, I and J, in which rpl-1 and as1-1 rpl-1 are in the er background. Scale bars: 1 mm in C,D; 100 µm in A,B,E-L.