Expression analysis of an APETALA1/FRUITFULL-like gene in Phalaenopsis sp. ‘Hatsuyuki’ (Orchidaceae)

Members of the APETALA1 (AP1)/FRUITFULL (FUL)-like gene family of MADS-box genes play important roles in controlling the development of floral organs. To understand the molecular mechanisms of floral development in orchid, we isolated and characterized a Phalaenopsis AP1/FUL-like gene, PhalFUL. The results of phylogenetic analysis indicated that PhalFUL is in the monocots group of AP1/FUL-like gene. PhalFUL transcripts were detected in the flower buds, but not in vegetative organs. Moreover, in situ hybridization experiments revealed PhalFUL hybridization signals in all floral organ primordia at a very early stage of floral development, and continued expression in the column of whorls 3 and 4 until late developmental stages. These expression patterns were similar to those of the FUL-like genes in Arabidopsis (FUL) and Antirrhinum (DEFH28), suggesting that the PhalFUL is similar in function to FUL and DEFH28.