title: Nucleotide polymorphism affecting FLC expression underpins heading date variation in horticultural brassicas.
abstract: Variation in flowering time and response to overwintering has been exploited to breed brassica vegetables that can be harvested year-round. Our knowledge of flowering time control now enables the investigation of the molecular basis of this important variation. Here, we show that a major determinant of heading date variation in Brassica oleracea is from variation in vernalization response through allelic variation at FLOWERING LOCUS C.C2 (BoFLC4). We characterize two alleles of BoFLC.C2 that are both functional and confer a requirement for vernalization, but they show distinct expression dynamics in response to cold. Complementation experiments in Arabidopsis thaliana revealed that the allelic variation results from cis polymorphism at BoFLC.C2, which quantitatively influences the degree of cold-induced epigenetic silencing. This results in one allelic variant conferring consistently later heading under both glasshouse and field conditions through reduced environmental sensitivity. Our results suggest that breeding of brassica varieties for commercially valuable variation in heading date has been achieved through the selection of cis polymorphism at FLC, similar to that underpinning natural variation in A. thaliana. This understanding will allow for the selection of alleles with distinct sensitivities to cold and robust heading dates under variable climatic conditions, and will facilitate the breeding of varieties more resistant to climate change.
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Irwin
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
authors.forename: Eleni
authors.initials: E
authors.lastname: Soumpourou
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
authors.forename: Clare
authors.initials: C
authors.lastname: Lister
authors.affiliation: Bejo Zaden B.V., Trambaan 1, 1749 CZ, Warmenhuizen, the Netherlands.
authors.forename: Jan-Dick
authors.initials: JD
authors.lastname: Ligthart
authors.affiliation: Elsoms Seeds Ltd, Pinchbeck Road, Spalding, PE11 1QG, UK.
authors.forename: Sue
authors.initials: S
authors.lastname: Kennedy
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK. caroline.dean@jic.ac.uk.
authors.forename: Caroline
authors.initials: C
authors.lastname: Dean
mesh_terms: D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000235:genetics; D001937:Brassica / Q000235:genetics*; D003080:Cold Temperature; D035264:Flowers / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D026161:MADS Domain Proteins / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D030821:Plants, Genetically Modified; D011110:Polymorphism, Genetic; D040641:Quantitative Trait Loci
chemical_list: D029681:Arabidopsis Proteins; C418902:At5g10140 protein, Arabidopsis; D026161:MADS Domain Proteins; D010940:Plant Proteins
keywords: Brassica oleracea; FLC; accession numbers KU521322/3; environmental sensitivity; vernalization