University of Dundee Evolutionary relationships among barley and Arabidopsis core circadian clock and clock-associated genes Calixto, Cristiane P. G.; Waugh, Robbie; Brown, John W. S. Published in: Journal of Molecular Evolution DOI: 10.1007/s00239-015-9665-0 Publication date: 2015 Document Version Publisher's PDF, also known as Version of record Link to publication in Discovery Research Portal Citation for published version (APA): Calixto, C. P. G., Waugh, R., & Brown, J. W. S. (2015). Evolutionary relationships among barley and Arabidopsis core circadian clock and clock-associated genes. 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Sep. 2021 J Mol Evol (2015) 80:108–119 DOI 10.1007/s00239-015-9665-0 ORIGINAL ARTICLE Evolutionary Relationships Among Barley and Arabidopsis Core Circadian Clock and Clock-Associated Genes Cristiane P. G. Calixto • Robbie Waugh • John W. S. Brown Received: 22 September 2014 / Accepted: 6 January 2015 / Published online: 22 January 2015 Ó The Author(s) 2015. This article is published with open access at Springerlink.com Abstract The circadian clock regulates a multitude of Keywords Arabidopsis thaliana Á Hordeum vulgare plant developmental and metabolic processes. In crop (barley) Á Circadian clock Á Reciprocal BLAST Á species, it contributes significantly to plant performance Homologue and productivity and to the adaptation and geographical range over which crops can be grown. To understand the clock in barley and how it relates to the components in the Introduction Arabidopsis thaliana clock, we have performed a system- atic analysis of core circadian clock and clock-associated Most living organisms optimise their day/night responses genes in barley, Arabidopsis and another eight species by measuring time and using this information to organize including tomato, potato, a range of monocotyledonous their physiology and morphology in anticipation of daily species and the moss, Physcomitrella patens. We have changes (Chen and McKnight 2007; Green et al. 2002; identified orthologues and paralogues of Arabidopsis genes Okamura 2004). As sessile organisms, plants also rely on which are conserved in all species, monocot/dicot differ- the circadian clock to optimise several physiological pro- ences, species-specific differences and variation in gene cesses, such as expression of chlorophyll biosynthetic copy number (e.g. gene duplications among the various genes after dawn, to optimise chlorophyll content and species). We propose that the common ancestor of barley carbon fixation (Dodd et al. 2005; Harmer et al. 2000; and Arabidopsis had two-thirds of the key clock compo- Haydon et al. 2013). The diversity of processes controlled nents identified in Arabidopsis prior to the separation of the by the circadian clock also reflects the number of genes monocot/dicot groups. After this separation, multiple under its control. Expression of about one-third of the independent gene duplication events took place in both Arabidopsis genome is regulated by the circadian clock monocot and dicot ancestors. (Covington et al. 2008). Only a relatively small number of genes establish and maintain the circadian rhythm of the clock. These core clock components are present in each cell and consist of a complex network of genes regulated by transcriptional feedback loops, post-transcriptional and Electronic supplementary material The online version of this post-translational modifications (Gallego and Virshup article (doi:10.1007/s00239-015-9665-0) contains supplementary 2007; James et al. 2012; McClung 2014; Sanchez et al. material, which is available to authorized users. 2010; Troein et al. 2009) (Fig. 1). The framework of the Arabidopsis circadian clock known as the interlocking-loop C. P. G. Calixto Á R. Waugh Á J. W. S. Brown (&) Division of Plant Sciences, University of Dundee at the James model comprises at least three interlocking gene expression Hutton Institute, Invergowrie, Dundee DD2 5DA, UK feedback loops (Harmer 2010; Locke et al. 2006; Pokhilko e-mail: [email protected]; [email protected] et al. 2010; Zeilinger et al. 2006). The central loop is formed by CIRCADIAN CLOCK R. Waugh Á J. W. S. Brown Cell and Molecular Sciences, The James Hutton Institute, ASSOCIATED 1 (CCA1), LATE ELONGATED HYPOCOTYL Invergowrie, Dundee DD2 5DA, UK (LHY)andTIMING OF CHLOROPHYLL A/B BINDING 123 J Mol Evol (2015) 80:108–119 109 ELF3 evening loop is the Evening Complex (EC). The EC is 00 composed of EARLY FLOWERING 3 (ELF3), ELF4, and LUX and it represses transcription of PRR9 (Chow et al. ELF4 03 2012). Interestingly, LUX represses its own expression ELF4 21 ELF3 PRR7 (Helfer et al. 2011). Further post-translational regulation PRR9 LUX takes place in the evening, such as GI degradation by ELF3 T O (Yu et al. 2008) and F-box protein ZEITLUPE (ZTL) C 1 CCA1 stabilisation by GI, allowing ZTL to control TOC1 protein 18 06 degradation (Kim et al. 2007). L LHY L U H The circadian clock can be entrained by certain cues, for X Y C instance light (photoperiod) and temperature (Hotta et al. PRR5 C Z A T 1 2007), which is tightly linked to plant adaptation to specific L TOC1 ZTL GI environments (Michael et al. 2003). To address the impact GI 15 09 of the clock in crop species, such as barley, one approach is PRR3 FKF1 to gain an understanding of key clock components and their PRR5 12 interactions by examining how widely clock genes are PRR7 PRR9 conserved. Most information on plant circadian clocks is available for Arabidopsis (Nagel and Kay 2012; Nakamichi Fig. 1 Feedback loops of the Arabidopsis clock. Simplified sche- matic diagram of the 24-h Arabidopsis clock. Feedback loops of the 2011). Translation of knowledge will not be straight for- core clock genes are represented in the centre. Full lines represent ward due to differences in clock control between monocots transcriptional feedback loops, whereas dashed lines represent post- and Arabidopsis, such as rhythmicity of growth (Matos translational regulation. Arrows represent activation, while arrows et al. 2014; Poire´ et al. 2010) and different versions of the with blunt ends represent repression. The diagram represents a compilation of gene regulation from numerous publications referred clock operating in different parts of the plant (Endo et al. to in the ‘‘Introduction’’. For simplicity, the PRR3 component was not 2014; James et al. 2008). Understanding the evolutionary included in the above regulatory network. Expression peaks of clock relationships among clock genes will aid the development genes are represented at different times of the day and night in the of clock models for other species but it is important to note outer circle (Nakamichi 2011) that the identification of barley homologous genes does not necessarily imply conserved clock function. To date, some PROTEIN 1 (TOC1—also known as PSEUDO RESPONSE clock genes have been identified in monocots such as REGULATOR 1, PRR1)(Alabadı´ et al. 2001). CCA1 and Brachypodium distachyon (Higgins et al. 2010) and Zea LHY are closely related and partially redundant myeloblas- mays (Wang et al. 2011) with most information on rice tosis (MYB) transcription factors that accumulate at dawn and (Hayama et al. 2003; Higgins et al. 2010; Iwamoto et al. bind to the promoter region of TOC1, inhibiting its expression. 2009; Murakami et al. 2007; Onai and Ishiura 2005; Shin Recent studies suggest that TOC1 is responsible for reducing et al. 2004). For barley, circadian rhythms have been CCA1 and LHY expression (Gendron et al. 2012; Huang et al. observed at diverse levels including at transcript and pro- 2012;Pokhilkoetal.2012). During the morning, CCA1 and tein abundance, and physiological processes (Lillo 2006; LHY play parallel roles in the central loop by inducing Martı´nez et al. 2003; Nagasaka et al. 2009; Vallelian- expression of the transcriptional repressors PSEUDO Bindschedler et al. 1998). Diurnal and circadian expression RESPONSE REGULATOR 7 and 9 (PRR7 and PRR9), analyses have been reported for HvLHY (HvCCA1), which along with PSEUDO RESPONSE REGULATOR 5 HvPPD-H1, HvPRR73, HvPRR59, HvPRR95, HvGI, (PRR5) inhibit expression of CCA1 and LHY (Locke et al. HvTOC1, HvLUX and HvELF3 (Campoli et al. 2012b, 2006; Nakamichi et al. 2010; Zeilinger et al. 2006). This 2013; Dunford et al. 2005; Faure et al. 2012; Higgins et al. molecular link between CCA1/LHY and PRR7/9/5 during the 2010; Turner et al. 2005). Only three barley clock genes morning constitutes a second feedback loop called the have been well characterised using mutant plants: Ppd-H1, ‘morning loop’. ELF3 and LUX (Campoli et al. 2013; Faure et al. 2012; Further regulatory clock control is carried out by CCA1 Turner et al. 2005; Zakhrabekova et al. 2012). The Ppd- and LHY through transcriptional inhibition of EARLY H1/PRR37 allele is the major determinant of photoperiod FLOWERING 3 and 4 (ELF3 and ELF4), LUX AR- response in barley and is the putative AtPRR7 orthologue RHYTHMO (LUX, also known as PHYTOCLOCK 1, (Turner et al. 2005). Mutations in the barley Ppd-H1/ PCL1), and GIGANTEA (GI) genes (Nagel and Kay 2012).