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, A. magenta, and A. 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 2 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 3 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.

Evolution and Expression Patterns of TCP Genes in Asparagales

“…Expression of CYC/TB1 genes in Orchidaceae contrasts with studies in Commelinales, Zingiberales, and Alstroemeriaceae that show differential dorsiventral expression of CYC/TB1 genes and hence support convergent recruitment of CYC homologs in the acquisition of bilateral symmetry in different monocots (Bartlett and Specht, 2011; Preston and Hileman, 2012; Hoshino et al, 2014). Within core eudicots, only the CYC2/TCP1 clade members have been linked to shifts toward bilateral floral symmetry.…”

Analysis of the TCP genes expressed in the inflorescence of the orchid Orchis italica

“…Zygomorphic flowers have evolved independently multiple times during the angiosperm evolution. The involvement of CYC/TB1 -like genes in the evolution and maintenance of bilateral symmetry in dicots has been extensively analyzed 5 22 23 24 25 26 27 28 , whereas only a few studies are available for monocots 29 30 31 32 . Other members of the CYC/TB1 -like genes, e.g.…”

Generation and classification of transcriptomes in two Croomia species and molecular evolution of CYC/TB1 genes in Stemonaceae

“…Then, the Neighbor-Joining (NJ) phylogenetic tree was constructed using MEGA v7 (Kumar et al., 2016) with 1000 bootstrap replicates. To further determine ortholog or copy number of newly-determined Stemonaceae CYC/TB1-like sequences, a total of 72 amino acid sequences, which have been confirmed to be related to the formation of flower symmetry (Yuan et al., 2009, Bartlett and Specht, 2011, Preston and Hileman, 2012, Hoshino et al., 2014, Citerne et al., 2017) plus 7 newly-determined Stemonaceae sequences were used to generate Bayesian inference (BI) and maximum likelihood (ML) trees. The best-fitting model (JTT + G + I) was selected by ProtTest v2.4 (Abascal et al., 2005).…”

“…Caprifoliaceae and Lonicera (Howarth et al., 2011); Commelinaceae (Preston and Hileman, 2012); Ranunculaceae (Jabbour et al., 2014)] have demonstrated that CYC/TB1- like genes (sometimes referred to as TB1- like or TBL in monocots), which belong to the class II TCP ( T B1, C YC and P CF) family, are involved in the establishment and maintenance of zygomorphic flowers. However, to date, few studies are available for monocots (Bartlett and Specht, 2011; Preston and Hileman, 2012, Hoshino et al., 2014), and no TCP or CYC/TB1 genes have been identified from Stemonaceae.…”