GENETIC-ANALYSIS OF THE COMPONENTS OF WINTERHARDINESS IN BARLEY (HORDEUM-VULGARE L.)

Winterhardiness in cereals is the consequence of a number of complex a nd interacting components: cold tolerance, vernalization requirement a nd photoperiod sensitivity. An understanding of the genetic basis of t hese component traits should allow for more effective selection. Genom e map-based analyses hold considerable promise for dissecting complex phenotypes. A 74-point linkage map was developed from one hundred doub led haploid lines derived from a winter x spring barley cross and used as the basis for quantitative trait lows (QTL) analyses to determine the chromosome location of genes controlling components of winterhardi ness. Despite the greater genome coverage provided by the current map, a previously-reported interval an chromosome 7 remains the only regio n where significant QTL effects for winter survival ware detected in t his population. QTLs for heading date under 24 h light map to the same region. A QTL for heading date under this photoperiod regime also map s to chromosome 2. A distinct set of QTLs mapping to chromosomes 1, 2, 3 and 5 determined heading date under 8 h light. Patterns of differen tial QTL expression underscore the complexity of winterhardiness.