Figure 3

DArT-BSA genome scan for the 'pubescent leaves' ( mPub ) locus in the Steptoe/Morex DH population. The difference in the frequency of Steptoe alleles between different pairs of DNA pools is shown as a function of the cM positions of markers previously incorporated into a DArT consensus map for barley (375 of 418 polymorphic markers) [20]. The 'Bulks ( mPub )' panel displays data from the comparison between bulks contrasting for the mPub locus on chromosome 3H (40 plants each). The black arrow indicates the position of the mPub locus on the DArT consensus map [20] according to which the DH plants had been distributed into bulks. The 'Random bulks' panel displays data from a comparison of two randomly assorted bulks of 40 plants each. The 'Self comparison' panel shows the result of a comparison of two identical aliquots of a 1:1 mixture of Steptoe and Morex. Vertical lines within each of the panels denote borders between individual chromosomes. Horizontal lines indicate two types of significance thresholds. The 'pooling noise' significance threshold was based on a simulation of the bulking process (see Figure 2). The 'platform noise' significance threshold was derived from an analysis of the distribution of values in the self comparison (bottom panel) and Bonferroni- adjusted for multiple comparisons (see section entitled 'Polymorphic marker identification' in Materials and Methods).