Genetic interaction between GROWTHREGULATING FACTOR and CUP-SHAPED COTYLEDON in organ separation

TheArabidopsis thaliana GROWTH-REGULATING FACTOR(GRF)gene family comprises 9 members and encodes a class of transcription factors. We previously demonstrated thatGRFgenes played an essential role in formation of the boundary region between cotyledons, since their loss-of-function mutants developed fused cotyledons. Our present study shows that thegrfmutants display fusedfloral organs as well. Such fusion phenotypes of embryonic and postembryonicfloral organs are highly reminiscent of thecup-shaped cotyledon(cuc)mutants. In order to test a genetic interaction between GRFs andCUCs, we constructedcuc1 grf1/2/3, cuc2 grf1/2/3,andcuc3 grf1/2/3quadruple mutants, and found that the mutants showed dramatic increases in cotyledon fusion as well asfloral organ fusion. The results suggest that the signaling pathway ofGRFs may be genetically associated with that ofCUCs in the organ separation process.