Figure 3. QTL for insect resistance and defense-related traits in Da(1)-12×Ei-2 recombinant inbred lines.
A. QTL for resistance against Pieris brassicae, obtained with composite interval mapping (CIM). The horizontal red line indicates the significance threshold for this trait. B. Bayesian interval mapping (BIM) detects the same QTL as CIM. Horizontal red lines indicate high density probability regions in BIM, vertical red lines high density probability peaks. C. Additive effects in BIM, shown as a scatter plot with a smoothing spline fit (solid blue line) plus or minus two standard errors (dashed blue lines). For all six QTL, Pieris larvae cause greater damage when plants carry the Ei-2 alleles at the QTL. Hence, the Da(1)-12 alleles confer higher resistance. D. QTL for resistance against specialist lepidopterans, plant diameter, myrosinase activity, trichome density on the leaf upper and under-sides and perimeter, and for glucosinolates. For glucosinolates, QTL for individual compounds and for sum variables are given. Abbreviations are as follows: 3OHP = 3-hydroxypropyl; 3MSOP = 3-methylsulfinylpropyl; 4MSOB = 4-methylsulfinylbutyl; 7MSOH = 7-methylsulfinylheptyl; 8MSOO = 8-methylsulfinyloctyl; 8MTO = 8-methylthiooctyl; I3M = indol-3-yl-methyl; 1MO-I3M = 1-methoxy-indol-3-yl-methyl; 4OH-I3M = 4-hydroxy-indol-3-yl-methyl; 4MO-I3M = 4-methoxy-indol-3-yl-methyl. Total 3, 4, 7 and 8 are the sums of homomethionine-, di-homomethionine-, penta-homomethionine-, and hexa-homomethionine-derived glucosinolates, respectively. Total MSO, MT, and alkenyls are the sums of aliphatic glucosinolates with methylsulfinyl-, methylthio-, and alkenyl-groups, respectively. Total aliphatics and indoles are the sums of methionine- and tryptophan-derived glucosinolates, respectively, and total GS is the sum of all glucosinolates. Colored arrows correspond to 2-LOD support intervals for QTL identified with CIM, black arrows for high density probability regions in BIM, with vertical black bars showing the position of the high density probability peaks. Arrow directions correspond to effect directions; arrows pointing left indicate that the Ei-2 allele has a stronger effect on a particular trait. Arrow fill colors code for the relative effect strength of a QTL, arrow background colors for R 2, the percentage of variance explained by a QTL. Horizontal red lines connecting colored arrows indicate epistatic interactions between QTL.