To find genes involved in the floral organogenesis of Prunus lannesiana,cDNAs for one MADS-box genes,PrseAP3 with GenBank accession No.JF710371,was cloned using homologous cloning and 3′-RACE method based on the sequence database of NCBI.The full length of PrseAP3 cDNA is 977 bp,containing an open reading frame (ORF) of 708 bp and coding for a polypeptide of 235 amino acid residues.Sequence comparison and phylogenetic analysis revealed that PrseAP3 was highly homologous to protein AP3 in Arabidopsis and belonged to the paleoAP3 clade of class B.However,semiquantitative RT-PCR analysis showed that PrseAP3 was strongly expressed in petal and stamen of single-flowered P.lannesiana cultivar ‘Makino’,and in petal,stamen and leaf-like carpel of double-flowered cultivar ‘Hisakura’,obviously different from the expression pattern of AP3 in Arabidopsis.