Validating quantitative trait loci for diastatic power in populations of malting barley (hordeum vulgare L.)

Abstract

The combined and coordinated action of starch degrading enzymes is termed diastatic power, with α-amylase and β-amylase activity most highly correlated (Evans et al. 1995). Consequently enhanced expressions of these two enzymes are important malting quality barley breeding objectives. These quantitative traits typically exhibit low heritability, environmental influence, and continuous phenotypic variation (Tanksley, 1993) making detection of superior individuals difficult. QTL detection has contributed to an understanding of the genetic control of quantitative traits. Extensive QTL mapping information allows informed breeding decisions and efficient genome based selection strategies to be devised. A validation process is required to establish the usefulness of marker assisted selection (MAS) to improve quantitative traits. This involves estimating the weighted influence of selected QTL on the associated trait and measuring its relative expression when introgressed into alternative genetic backgrounds. The routine implementation of MAS in breeding programs has often been slow or failed because the validation step has not been completed.