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Open Access item HvFT1 (VrnH3) drives latitudinal adaptation in Spanish barleys

Authors:Casas Cendoya, Ana María
Djemel, Abderrahmane
Ciudad, Francisco J.
Yahiaoui, Samia
Ponce, Luis J.
Contreras-Moreira, Bruno
Gracia Gimeno, María Pilar
Lasa Dolhagaray, José Manuel
Igartua Arregui, Ernesto
Keywords:barley, heading date, vernalization, photoperiod, HvFT1
Issue Date:May-2011
Citation:Casas AM, Djemel A, Ciudad FJ, Yahiaoui S, Ponce LJ, Contreras-Moreira B, Gracia MP, Lasa JM, Igartua E. HvFT1 (VrnH3) drives latitudinal adaptation in Spanish barleys. Theoretical and applied genetics 122 (7): 1293-1304 (2011)
Abstract:Flowering time is an important factor in the adaptation of barley varieties to environmental conditions and maximizing yield potential (Boyd et al. 2003; Cockram et al. 2007a; Cuesta-Marcos et al. 2009), by synchronizing the plant cycle to the prevailing environmental conditions. Flowering time is a complex trait that shows an almost continuous variation in cereals. The investigation of the genetic control of flowering time in barley has benefited from the comparative use of floral pathways in Arabidopsis thaliana (Cockram et al. 2007a) and rice, via the identification of candidate genes through orthology. The variation in flowering time is mainly due to variations in genes regulated by day length (photoperiod) or long exposures to low temperature (vernalization) (Laurie et al. 1995; Trevaskis et al. 2003; Dubcovsky et al. 2005). In barley, three genes are responsible for the vernalization requirement: VrnH1 (isolated by map-based cloning in diploid wheat, Yan et al. 2003), VrnH2 (identified by positional cloning, Yan et al. 2004) and VrnH3 (identified by homology to a known gene from Arabidopsis thaliana, Yan et al. 2006). VrnH1 is induced by vernalization and promotes the transition from vegetative to reproductive development. VrnH2 is a floral repressor that delays flowering until the plants are vernalized. The VrnH3 gene seems to be orthologous to the A. thaliana floral pathway integrator FT (FLOWERING LOCUS T) gene (Yan et al. 2006; Faure et al. 2007; Turck et al. 2008; Kikuchi et al. 2009). In A. thaliana, FT expression increases in the leaves when plants are exposed to inductive day length. In barley, expression of orthologous HvFT1 (synonymous to VrnH3) is induced by long day conditions and promotes flowering (Hemming et al. 2008). The winter growth habit of barley requires the presence of a recessive VrnH1 allele, together with an active VrnH2 allele (Cockram et al. 2007b; Hemming et al. 2009). Vernalization induces VrnH1 under both short and long days, which then represses VrnH2. Distelfeld et al. (2009) reported that the interactions among the three vernalization genes generate a feedback regulatory loop that once started, leads to an irreversible induction of flowering. The function of HvFT1 has started to be unraveled only recently. There is now mounting evidence supporting the role of the FT protein in Arabidopsis (and corresponding proteins in other species) as an important part of the florigen (Corbesier et al. 2007; Tamaki et al. 2007). Kikuchi et al. (2009) presented strong evidence suggesting that HvFT1 plays a central role in promoting flowering, integrating the photoperiod and vernalization pathways. HvFT1 expression seems to be regulated by the major photoperiod response genes: PpdH1 under LD conditions and PpdH2 under SD conditions. There are evidences on the adaptive role played by VrnH1, VrnH2 and PpdH1 during the expansion of the crop, facilitating its adaptation to new agroecological niches (Cockram et al. 2007a; Jones et al. 2008). Does VrnH3-HvFT1 also have an adaptive role? We know that the phenotypic effect of HvFT1 on flowering time can be very large (Yan et al. 2006), and therefore may be an important factor for the final determination of barley flowering time. Other open questions on this gene are: to what environmental cue does VrnH3 respond, temperature or photoperiod? What effect does it have on flowering time under natural conditions? To address these questions, we analyzed the polymorphism and the phenotypic effect of this gene on a collection of Spanish barley landraces and its variation at the sequence level, and validated its effect on a segregating population.
Description:29 Pag., 5 Tabl., 4 Fig. The definitive version is available at: http://www.springer.com/life+sciences/plant+sciences/journal/122
Publisher version (URL):http://dx.doi.org/10.1007/s00122-011-1531-x
E-ISSNmetadata.dc.identifier.doi = DOI:1432-2242
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