TitleValidation of the VRN-H2/VRN-H1 epistatic model in barley reveals that intron length variation in VRN-H1 may account for a continuum of vernalization sensitivity.
Publication TypeJournal Article
Year of Publication2007
AuthorsSzucs, P, Skinner, JS, Karsai, I, Cuesta-Marcos, A, Haggard, KG, Corey, AE, Chen, THH, Hayes, PM
JournalMol Genet Genomics
Date Published2007 Mar
KeywordsAcclimatization, Alleles, Amino Acid Sequence, Base Sequence, Crosses, Genetic, DNA Primers, DNA, Plant, Epistasis, Genetic, Genes, Plant, Genetic Variation, Hordeum, Introns, Models, Genetic, Molecular Sequence Data, Photoperiod, Phylogeny, Plant Proteins, Sequence Homology, Amino Acid

The epistatic interaction of alleles at the VRN-H1 and VRN-H2 loci determines vernalization sensitivity in barley. To validate the current molecular model for the two-locus epistasis, we crossed homozygous vernalization-insensitive plants harboring a predicted "winter type" allele at either VRN-H1 (Dicktoo) or VRN-H2 (Oregon Wolfe Barley Dominant), or at both VRN-H (Calicuchima-sib) loci and measured the flowering time of unvernalized F(2) progeny under long-day photoperiod. We assessed whether the spring growth habit of Calicuchima-sib is an exception to the two-locus epistatic model or contains novel "spring" alleles at VRN-H1 (HvBM5A) and/or VRN-H2 (ZCCT-H) by determining allele sequence variants at these loci and their effects relative to growth habit. We found that (a) progeny with predicted "winter type" alleles at both VRN-H1 and VRN-H2 alleles exhibited an extremely delayed flowering (i.e. vernalization-sensitive) phenotype in two out of the three F(2) populations, (b) sequence flanking the vernalization critical region of HvBM5A intron 1 likely influences degree of vernalization sensitivity, (c) a winter habit is retained when ZCCT-Ha has been deleted, and (d) the ZCCT-H genes have higher levels of allelic polymorphism than other winterhardiness regulatory genes. Our results validate the model explaining the epistatic interaction of VRN-H2 and VRN-H1 under long-day conditions, demonstrate recovery of vernalization-sensitive progeny from crosses of vernalization-insensitive genotypes, show that intron length variation in VRN-H1 may account for a continuum of vernalization sensitivity, and provide molecular markers that are accurate predictors of "winter vs spring type" alleles at the VRN-H loci.

Alternate JournalMol. Genet. Genomics
PubMed ID17151889