Background: APETALA3 (AP3) has significant roles in petal and stamen development in accordance with the classical ABC model.

Results: The AP3 homolog, CDM19, from Chrysanthemum morifolium cv. Jinba was cloned and sequenced. Sequence and phylogenetic analyses revealed that CDM19 is of DEF/AP3 lineage possessing the characteristic MIKC-type II structure. Expression analysis showed that CDM19 was transcribed in petals and stamens of ray and disc florets with weak expression in the carpels. Ectopic expression of CDM19 in Arabidopsis wild-type background altered carpel development resulting in multi-carpel siliques. CDM19 could only partially rescue the Arabidopsis ap3‐–3 mutant.

Conclusions: Our results suggest that CDM19 may partially be involved in petal and stamen development in addition to having novel function in carpel development.