title: Changes in Lolium perenne transcriptome during cold acclimation in two genotypes adapted to different climatic conditions.
abstract: BACKGROUND
  Activation of numerous protective mechanisms during cold acclimation is important for the acquisition of freezing tolerance in perennial ryegrass (Lolium perenne L.). To elucidate the molecular mechanisms of cold acclimation in two genotypes ('Veyo' and 'Falster') of perennial ryegrass from distinct geographical origins, we performed transcriptome profiling during cold acclimation using RNA-Seq.
  
  
  METHODS
  We cold-acclimated plants from both genotypes in controlled conditions for a period of 17 days and isolated Total RNA at various time points for high throughput sequencing using Illumina technology. RNA-seq reads were aligned to genotype specific references to identify transcripts with significant changes in expression during cold acclimation.
  
  
  RESULTS
  The genes induced were involved in protective mechanisms such as cell response to abiotic stimulus, signal transduction, redox homeostasis, plasma membrane and cell wall modifications, and carbohydrate metabolism in both genotypes. 'Falster' genotype, adapted to cold climates, showed a stronger transcriptional differentiation during cold acclimation, and more differentially expressed transcripts related to stress, signal transduction, response to abiotic stimulus, and metabolic processes compared to 'Veyo'. 'Falster' genotype also showed an induction of more transcripts with sequence homology to fructosyltransferase genes (FTs) and a higher fold induction of fructan in response to low-temperature stress. The circadian rhythm network was perturbed in the 'Veyo' genotype adapted to warmer climates.
  
  
  CONCLUSIONS
  In this study, the differentially expressed genes during cold acclimation, potentially involved in numerous protective mechanisms, were identified in two genotypes of perennial ryegrass from distinct geographical origins. The observation that the circadian rhythm network was perturbed in 'Veyo' during cold acclimation may point to a low adaptability of 'Veyo' to low temperature stresses. This study also revealed the transcriptional mechanisms underlying carbon allocation towards fructan biosynthesis in perennial ryegrass.
authors.affiliation: Department of Agroecology - Crop Health, Aarhus University, Slagelse, Denmark. Shamila.abeynayake@agro.au.dk.|Department of Molecular Biology and Genetics, Science and Technology, Aarhus University, Slagelse, Denmark. Shamila.abeynayake@agro.au.dk.
authors.forename: Shamila Weerakoon
authors.initials: SW
authors.lastname: Abeynayake
authors.affiliation: Department of Molecular Biology and Genetics, Science and Technology, Aarhus University, Slagelse, Denmark. stephen.byrne@mbg.au.dk.
authors.forename: Stephen
authors.initials: S
authors.lastname: Byrne
authors.affiliation: Department of Molecular Biology and Genetics, Science and Technology, Aarhus University, Slagelse, Denmark. istvan.nagy@mbg.au.dk.
authors.forename: Istvan
authors.initials: I
authors.lastname: Nagy
authors.affiliation: Laboratory of Genetics and Physiology, Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry, Kėdainiai distr, Lithuania. kristinaja@dobilas.lzi.lt.
authors.forename: Kristina
authors.initials: K
authors.lastname: Jonavičienė
authors.affiliation: Department of Agroecology - Crop Health, Aarhus University, Slagelse, Denmark. Thomas.Etzerodt@agrsci.dk.
authors.forename: Thomas Povl
authors.initials: TP
authors.lastname: Etzerodt
authors.affiliation: Department of Agroecology - Crop Health, Aarhus University, Slagelse, Denmark. Birte.Boelt@agro.au.dk.
authors.forename: Birte
authors.initials: B
authors.lastname: Boelt
authors.affiliation: Department of Molecular Biology and Genetics, Science and Technology, Aarhus University, Slagelse, Denmark. torben.asp@mbg.au.dk.
authors.forename: Torben
authors.initials: T
authors.lastname: Asp
mesh_terms: D000064:Acclimatization / Q000235:genetics*; D002244:Carbon / Q000378:metabolism; D002980:Climate; D016000:Cluster Analysis; D003080:Cold Temperature; D005630:Fructans / Q000096:biosynthesis / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D008129:Lolium / Q000235:genetics*; D008954:Models, Biological; D025341:Principal Component Analysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012995:Solubility; D059467:Transcriptome / Q000235:genetics*; D014867:Water / Q000737:chemistry
chemical_list: D005630:Fructans; D012333:RNA, Messenger; D014867:Water; D002244:Carbon