Identification and molecular mapping of a dwarfing gene in barley (Hordeum vulgare L.) and its correlation with other agronomic traits

Ninety-two doubled haploid (DH) lines, generated from a cross between Franklin and TX9425 (a Chinese Landrace), were grown in three environments to identify quantitative trait loci (QTLs) controlling agronomic traits including heading date, plant height and spike characteristics. The DH lines showed a wide range of variations for all the agronomic traits tested. Most of the traits were controlled by one or two major QTLs which explained 9.5–80.9% of the phenotypic variation. Two dwarfing genes were identified from the cross. One of the dwarfing genes was from Franklin, which is the same as the previously reported denso gene. The other dwarfing gene was from the Chinese landrace variety. Both dwarfing genes were temperature and/or day length sensitive. The dwarfing gene from Franklin was more effective in early sowing trials (shorter day length and lower temperature) while the gene from TX9425 was more effective in later sown trials. The dwarfing gene from TX9425 was located at a similar position to the uzu gene. However, it differed from this gene being temperature sensitive with very close links to short spikes, awns and high grain density which is more like a brh gene. To effectively use this gene in a breeding program, it is necessary to break the linkage between the dwarfing gene and the unfavourable spike traits.