Effect of vernalization and photoperiod response genes on flowering time in a large barley population

This work was carried out with a large population of barley consisting of 480 lines doubled haploid from the cross between a Spanish landrace SBCC145 and the variety Beatrix. In this large population VrnH1, VrnH2 and PpdH1 are segregating, which has allowed us to consider the following objectives: 1) to determine the effect of one allele of the VrnH1 gene present in Spanish barleys, coming from areas with mild winters, on flowering, 2) to determine if long photoperiod sensitivity is affected by the presence of vernalization genes and, 3) to find QTLs for agronomic traits and flowering in a population of broad genetic basis including autochthonous germplasm, poorly studied until now. The population has been evaluated in the field, in autumn sowing, for days to heading, growth habit, vigor, and plant height. Heading was also assessed in another late sowing, in February, under the same experimental design. The entire population has been characterized with markers for genes VrnH1, VrnH2, VrnH3, PpdH1 and the region around the Eam6 earliness per se gene, of great importance in the Mediterranean region. A sub-sample of the population was characterized with SNP markers, using the Illumina Golden Gate system, which has enabled us to build a genetic map with 408 markers. QTLs have been detected for vigor, growth habit, flowering and plant height. There is a region on chromosome 3H, around the denso gene, which affects all the traits tested. Plants with the Beatrix allele at this QTL present prostrate growth habit, delayed flowering and a smaller size. In addition to these genes with large effect, we found several QTLs for plant height, vigor and flowering with antagonistic effects on both parents. No clear effect of the vernalization genes has been found in the entire population in autumn sowing, while the Eam6 region has a clear influence on flowering date, with nearly six days of difference between alleles. There is a significant effect of the PpdH1 alleles on heading in the winter-sowing. Finally, the possible use in breeding of these genes and QTLs is discussed