We isolated a gene encoding a putative MADS-box protein designated RcAGL15 from a protocorm-like body (PLB), a somatic embryogenetic structure) of Rosa canina L. RcAGL15 encodes a predicted protein of 251 amino acid residues with a molecular weight of 28 kDa and a theoretical isoelectric point of 7.5. Reverse-transcription polymerase chain reaction shows that RcAGL15 is mainly expressed in PLB and regenerated PLB, but not in leaves of aseptic seedlings, incubated leaflets before callus formation, calli, rhizoids, or leaves of regenerated shoots. Transgenic, ectopic expression of RcAGL15 in Arabidopsis changes numbers of floral organs and reduces content of indole-3-acetic acid, but increases levels of abscisic acid. Thus, RcAGL15 appears to be a new MADS-box gene that plays regulatory roles in morphological development and the number of flower organs, as well as somatic embryogenesis.