Allele frequencies in the -, - and - vernalization response and - and - photoperiod sensitivity genes, and their effects on heading in a diverse set of wheat cultivars ( L.).

Heading of cereals is determined by complex genetic and environmental factors in which genes responsible for vernalization and photoperiod sensitivity play a decisive role. Our aim was to use diagnostic molecular markers to determine the main allele types in -, -, -, - and - in a worldwide wheat collection of 683 genotypes and to investigate the effect of these alleles on heading in the field. The dominant -, - and - alleles were present at a low frequency. The - photoperiod-insensitive allele was carried by 57 % of the cultivars and was most frequent in Asian and European cultivars. The - photoperiod-insensitive allele was carried by 22 % of the genotypes from Asia, America and Europe. Nine versions of the --insensitive allele were identified based on gene copy number and intercopy structure. The allele compositions in -, - and - significantly influenced heading and together explained 37.5 % of the phenotypic variance. The role of gene model increased to 39.1 % when - intercopy structure was taken into account instead of overall - type (sensitive vs. insensitive). As a single component, - had the most important role (28.0 % of the phenotypic variance), followed by - (12.3 % for -_overall, and 15.1 % for -_intercopy) and - (2.2 %). Significant gene interactions were identified between the marker alleles within - and between - and the two genes. The earliest heading genotypes were those with the photoperiod-insensitive allele in - and -, and with the spring allele for - and the winter alleles for - and -. This combination could only be detected in genotypes from Southern Europe and Asia. Late-heading genotypes had the sensitivity alleles for both genes, regardless of the allelic composition of the genes. There was a 10-day difference in heading between the earliest and latest groups under field conditions.