Characterization offs8.1, a major QTL influencing fruit shape in tomato

In two previous quantitative trait locus (QTL) mapping studies conducted inLycopersicon esculentum x L. pimpinellifolium BC1 and BC2 populations we had localized a major QTL for fruit shape,fs8.1, to a ca. 20 cM interval on the short arm of chromosome 8, flanked by markers TG176 and CT92. At this QTL the allele from the wild species reduces the length of fruit, giving round-shaped fruit. In order to define more precisely the location offs8.1, near-isogenic lines (NILs) segregating for the region of interest were developed. The results from substitution mapping show that no recombination occurred betweenfs8.1 and the marker CD40 in 322 meioses. The gene action forfs8.1 was determined in a BC4F3 population to be partial dominance. The main effect offs8.1 is exerted on fruit length while fruit diameter is not significantly affected. A highly significant correlation (r=0.89;P