Association between the allele compositions of major plant developmental genes and frost tolerance in barley (Hordeum vulgare L.) germplasm of different origin

Changing climatic conditions with warming winters and shifts in the frequencies of drought, intense rainfall and cold spells together with associated changes in the geographical distribution of arable crops increase the challenges for selecting new varieties. In this context, we aim to contribute to a better understanding of the determinants of barley (Hordeum vulgare) frost tolerance (FRT) and consequent improvements to marker-assisted selection (MAS). Freezing injury in a diversity panel of 121 barley genotypes with different growth habits and origins was assessed using phenotyping based on chlorophyll fluorescence (F_v/F_m) measurements to screen genetic diversity in plants at an early growth stage. The haplotypes of vernalisation and photoperiod genes were determined with PCR, and correlation analyses were done using data from 12 laboratory and field-laboratory FRT tests. Previous results of allelic combinations of VRN-H1/VRN-H2 for FRT were confirmed with these experiments using a larger set of genotypes. The predictive power of polymorphisms in VRN-H1 intron 1 region for FRT was significantly higher than that of the VRN-H1 promoter polymorphism. The vrn-H1/vrn-H2 facultative genotypes had similar or higher FRT than vrn-H1/Vrn-H2 winter genotypes under suboptimal hardening conditions. Genes regulating long-day and short-day photoperiodic responses were significantly correlated with FRT. The most parsimonious model for prediction of FRT was based on polymorphisms in the VRN-H1 intron 1 region, VRN-H2 and PPD-H2 and explained 69% of the variation in FRT.