Validation 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.
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.
Szucs
Péter
P
Department of Crop and Soil Science, Oregon State University, 253 Crop Science Building, Corvallis, OR 97331, USA.
Skinner
Jeffrey S
JS
Karsai
Ildikó
I
Cuesta-Marcos
Alfonso
A
Haggard
Kale G
KG
Corey
Ann E
AE
Chen
Tony H H
TH
Hayes
Patrick M
PM
D000064:Acclimatization / Q000235:genetics; D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D003433:Crosses, Genetic; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004843:Epistasis, Genetic; D017343:Genes, Plant; D014644:Genetic Variation; D001467:Hordeum / Q000235:genetics*; D007438:Introns; D008957:Models, Genetic; D008969:Molecular Sequence Data; D017440:Photoperiod; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D018744:DNA, Plant; D010940:Plant Proteins