The relationship among freezing tolerance, vernalization requirement, Ppd alleles and winter hardiness in European wheat cultivars

Winter hardiness of wheat is a complex trait involving a system of structural, regulatory and developmental genes, which interact in a complex pathway. The objective of the present work was to study the relationship among the main traits determining the level of adaptation and the possibility for target manipulation of breeding material by using molecular markers and phenological parameters. Wheat cultivars from different ecoclimatic environments of Europe were included for analysis. Gene-specific assay showed that photoperiod sensitivity of the studied cultivars was determined by polymorphism in the Ppd-D1 allele. The study established the relationship among winter hardiness, LT50 (the temperature at which 50% of plants are killed), photoperiod sensitivity, vernalization duration and earliness per se genes in the environment of Lithuania. The cultivars from Northern and Western Europe exhibited stronger requirement for vernalization and photoperiod. Although the group of cultivars from the southern latitudes were characterized by earliness, they possessed a stronger level of LT50. The level of LT50 was found to be the most crucial component of winter hardiness, the other traits served as supplementary components.