Allelic variation and geographic distribution of vernalization genes HvVRN1 and HvVRN2 in Chinese barley germplasm

Knowledge of the allelic variation and epistatic interaction of vernalization genes is crucial to understanding seasonal growth habit and adaptability of genetic resources in cultivated (Hordeum vulgare) and wild (Hodeum spontaneum) barley. In this research, 1398 Chinese barley accessions were characterized with molecular markers for vernalization genes HvVRN1 and HvVRN2. Different combinations of haplotypes at these two vernalization genes were present at different frequencies in wild barley, landraces and modern cultivars. All of the HvVRN1 haplotypes except HvVRN1-7 (V 1-7 ) and HvVRN1-Hs (V 1-Hs ) were identified in the Chinese barley collection chosen for this study. Haplotype V 1-8 occurred at the highest frequency in spring V 1 alleles, and V 1-1 , V 1-4 and V 1-8 had broad geographic distributions in China. Haplotypes V 1-2 and V 1-3 are restricted to modern cultivars as they were introduced from exotic germplasm. A total of 18 HvVRN1/HvVRN2 multilocus haplotypes were identified. Most of the HvVRN1/HvVRN2 haplotypes were present in materials from the Yellow-Huai River Valley and Middle-Lower Yangtze Valley ecological zones, birthplace of Chinese farming. The predominant combinations in landraces were V 1-8 /V 2 and v 1 /V 2 , but v 1 /v 2 made up the highest proportion of modern cultivars. Haplotypes V 1-5 /v 2 , V 1-10 /V 2 and V 1-9 /V 2 showed a correlation with region. Our results confirmed the presence or absence of conserved regulatory elements and the length of the first intron of HvVRN1 plays a determinant role in the vernalization requirement of barley. This study provides useful information for breeding and utilization of Chinese barley germplasm.