Characterization of CYCLOIDEA-like genes in controlling floral zygomorphy in the monocotyledon Alstroemeria

Abstract

The CYCLOIDEA (CYC) gene controls the development of zygomorphic flowers and the determination of adaxial identity of floral organs in the model developmental system of Antirrhinum majus. However, whether CYC homologue genes also control floral zygomorphy in monocotyledon Alstroemeria plants is yet unknown. In this study, we investigated CYC-like genes in the monocotyledons Alstroemeria aurea, Alstroemeria magenta, and Alstroemeria pelegrina var. rosea, all of which have zygomorphic flowers. Since the CYC gene belongs to the T-complex protein (TCP) gene family of transcription factors, cloning of CYC-like sequences was performed using rapid amplification of cDNA ends (RACE)-polymerase chain reaction (PCR) by using degenerate primers designed for the TCP domain. We cloned 1 CYC-like sequence each from A. aurea (AaTCP1, accession number AB714967 in the GenBank/EMBL/DDBJ databases) and A. magenta (AmTCP1, AB714970), and two CYC-like sequences from A. pelegrina var. rosea (ApTCP1, AB714968; and ApTCP2, AB714969). The deduced amino acid sequences of AaTCP1, AmTCP1, ApTCP1, and ApTCP2 shared 67.7%, 67.7%, 71.0%, and 64.5% identities, respectively, with the TCP domain in CYC. Molecular phylogenetic analysis indicated that three CYC-like genes from Alstroemeria belonged to the ZinTBL1b clade in the CYC-/tb1-like subfamily. Reverse transcription (RT)-PCR and in situ hybridization analyses showed that AaTCP1 transcripts were specifically detected in flower buds and localized in the base of adaxial inner perianth of A. aurea. These results suggest that CYC-like genes are also involved in the development of floral asymmetry and the determination of adaxial identity of floral organs in the monocotyledon Alstroemeria.