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

Abstract

TCP proteins are plant-specific transcription factors involved in many different processes. Because of their involvement in a large number of developmental pathways, their roles have been investigated in various plant species. However, there are almost no studies of this transcription factor family in orchids. Based on the available transcriptome of the inflorescence of the orchid Orchis italica, in the present study we identified 12 transcripts encoding TCP proteins. The phylogenetic analysis showed that they belong to different TCP classes (I and II) and groups (PCF, CIN and CYC/TB1), and that they display a number of conserved motifs when compared with the TCPs of Arabidopsis and Oryza. The presence of a specific cleavage site for the microRNA miRNA319, an important post-transcriptional regulator of several TCP genes in other species, was demonstrated for one transcript of O. italica, and the analysis of the expression pattern of the TCP transcripts in different inflorescence organs and in leaf tissue suggests that some TCP transcripts of O. italica exert their role only in specific tissues, while others may play multiple roles in different tissues. In addition, the evolutionary analysis showed a general purifying selection acting on the coding region of these transcripts.

TCP Transcription Factors at the Interface between Environmental Challenges and the Plant’s Growth Responses

“…TCP effect on floral development was shown in a wide range of plant species, including Arabidopsis , Antirrhinum, annual candytuft ( Iberis amara ) (Busch and Zachgo, 2007; Busch et al, 2012), angiosperms like Aristolochia arborea and Saruma henryi (Horn et al, 2015), Gerbera species (Broholm et al, 2008), rice (Yuan et al, 2009), sunflowers (Fambrini et al, 2012), peas (Wang et al, 2008), ragworts (Kim et al, 2008), Morrow’s honeysuckle ( Lonicera morrowii ) (Howarth and Donoghue, 2006), Knautia macedonica (Berger et al, 2016), and orchids (De Paolo et al, 2015). …”

“… Phylogenetic tree of plant species in which TCP transcription factors are involved in branching (Takeda et al, 2003; Aguilar-Martínez et al, 2007; Poza-Carrión et al, 2007; Bai et al, 2012; Braun et al, 2012; Drummond et al, 2015; Nicolas et al, 2015; Muhr et al, 2016) (blue dots), flower development (Linnaeus and Rudberg, 1744; Keeble et al, 1910; Corley et al, 2005; Costa et al, 2005; Busch and Zachgo, 2007; Broholm et al, 2008; Kim et al, 2008; Nag et al, 2009; Yuan et al, 2009; Howarth et al, 2011; Busch et al, 2012; Tähtiharju et al, 2012; Claßen-Bockhoff et al, 2013; Juntheikki-Palovaara et al, 2014; De Paolo et al, 2015; Horn et al, 2015; Lucero et al, 2015; Wang et al, 2008; Wang X.et al, 2015; Yang et al, 2015; Berger et al, 2016) (purple dots) or leaf development (Kosugi and Ohashi, 1997; Nath et al, 2003; Palatnik et al, 2003; Koyama et al, 2007, 2010a,b; Ori et al, 2007; Efroni et al, 2008; Kieffer et al, 2011; Mimida et al, 2011; Sarvepalli and Nath, 2011; Danisman et al, 2012, 2013; Aguilar-Martínez and Sinha, 2013; Burko et al, 2013; Tao et al, 2013; Zhou et al, 2013; Ballester et al, 2015; Huang and Irish, 2015; Ma et al, 2016) (green dots), respectively. The phylogenetic tree was created using Phylotree and iTOL (Letunic and Bork, 2016).…”

Evolution and Expression Patterns of TCP Genes in Asparagales

“…The only two studies available in Orchidaceae are particularly intriguing as they show very different expression patterns of CYC/TB1-like orthologs. Whereas, the only copy of CYC/TB1-like in Orchis italica (OitaTB1) is expressed exclusively in leaves (De Paolo et al, 2015), two of three CYC/TB1-like copies in Phalaenopsis equestris, PeCYC1 and PeCYC2 , seem to be expressed in higher levels (2–10 times more) in the dorsal sepals and the labellum compared to the ventral sepal and the lateral petals (Lin et al, 2016). Furthermore, some authors have hypothesized that the expression gradient of TCP genes is largely controlled by upstream expression of the AP3/DEF petal-stamen identity genes, resulting in higher concentrations of CYC/TB1-like genes in the dorsal floral regions; however, more experimental data is needed to support this (Mondragón-Palomino and Theißen, 2009).…”

Genome-wide analysis of TCP family in tobacco

“…Among other things, the TCP transcription factors regulate embryonic growth, floral organ morphogenesis, pollen development, leaf development, seed germination, senescence, cell cycle regulation, circadian rhythm, and hormone signaling (Martín-Trillo and Cubas, 2010;Danismanet al, 2012;Uberti-Manassero et al, 2013). The TCP family proteins are studied in some dicotyledonous and monocotyledonous plants and all class I and class II proteins are reported to function as transcriptional activators and repressors in the control of plant growth and development (Uberti-Manassero et al, 2013;De Paolo et al, 2015). Although, the function of class II TCP proteins is well known, the data on the class I have been lacking.…”