Inheritance and identification of molecular markers associated with a novel dwarfing gene in barley

The Huaai 11 was crossed with tall varieties Monker, Mpyt, Zhenongda 3, Zaoshu 3, Advance, Huadamai 1, Huadamai 6, Hyproly and Ris01508. All the F1 plants displayed tall trait. Both tall and dwarf plants appeared in all the F2 populations with a 3:1 segregation ratio, suggesting that dwarfism of Huaai 11 is controlled by a single recessive gene, btwd1. Allelism test indicated that this dwarfing gene in the Huaai 11 is nonallelic with the gene br, uzu, sdw1 and denso. Using a double haploid population derived from a cross of Huadamai 6 and Huaai 11 and SSR markers the novel dwarfing gene was mapped onto the long arm of chromosome 7H, and closely linked to Bmac031 and Bmac167 with genetic distance of 2.2 cM.Huaai 11 is a new source of dwarf for broadening the genetic base of dwarfism. This dwarf source was controlled by a recessive dwarfing gene btwd1, was mapped onto the long arm of chromosome 7H.Dwarfism is a valuable trait in crop breeding, because it increases lodging resistance and decreases damages due to wind and rain [1]. Successful use of a dwarfing gene is critical for developing dwarf cultivars [2]. In barley, more than 30 types of dwarfs or semidwarfs have been found including 'breviaristatum-ari', 'brachytic-br', 'curly dwarf-cud', 'denso dwarf-denso', 'erectoides-ert', 'lazy dwarf-lzd', 'many noded dwarf-mnd', 'narrow leaf dwarf-nld', 'semidwarf-sdw', 'single node dwarf-sid', 'slender dwarf-sld', 'uzu or semibrachytic-uzu' and 'vegetative dwarf-dwf' [2-5]. However, only a few of them have successfully been used in barley breeding program. The dwarfing gene uzu on the chromosome 3HL has widely been used in barley breeding in China, Japan and Korea peninsula [6-10]. The dwarfing gene sdw1 (named as sdw previously) and denso have been used in feed barley breeding in North America and Australia [11-13], and in barley breeding in European [2,13], respectively. The sdw1 and denso genes were allelic [14-17], and were mapped onto the same region of chromosome 3H