Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 12/7/1997
Publication Date: N/A
Technical Abstract: Direct selection for malting quality in breeding programs is resource- intensive. More efficient approaches for identifying genotypes with good malting quality are highly desirable. The flanking markers, Brz and Amy2, and WG622 and BCD402B, for two major quantitative trait loci (QTL) regions for malt extract percentage, a-amylase activity, diastatic power, and malt b-glucan content on chromosome 1 (QTL1) and 4 (QTL2) were used for marker assisted selection (MAS) (Ullrich et al. 1997; Han et al. 1997). MAS was carried out in a population consisting of 92 doubled haploid lines derived from the "Steptoe" x "Morex" cross, which were not used in the original mapping efforts. Four alternative selection strategies: (1) phenotypic selection, (2) genotypic selection, (3) tandem genotypic and phenotypic selection, and (4) combined phenotypic and genotypic selection for malting quality. MAS for QTL1 (tandem genotypic and phenotypic selection, and combined phenotypic and genotypic selection) was more effective than phenotypic selection, but MAS for QTL2 was not as effective as phenotypic selection due to a lack of QTL2 effect in the selection population. Tandem genotypic and phenotypic selection makes MAS practical, for traits which are difficult or expensive to measure, such as most malting quality traits. MAS can substantially eliminate poor genotypes by early genotyping and keeping only desirable genotypes for later phenotypic selection.