QTL ANALYSIS OF MORPHOLOGICAL TRAITS IN A TOMATO RECOMBINANT INBRED LINE POPULATION

Quantitative trait loci (QTLs) influencing morphological traits were i dentified by restriction fragment length polymorphism (RFLP) analysis in a population of recombinant inbred lines (RILs) derived from a cros s of the cultivated tomato Lycopersicon esculentum with a related wild species, Lycopersicon cheesmanii. One hundred and thirty-two RFLP loc i spaced throughout the tomato genome were used as DNA probes on genom ic DNA from 97 RIL families. Morphological traits, including plant hei ght, plant fresh mass, number of branches, number of nodes, first flow er-bearing node, and leaf length, were evaluated in two controlled env ironment trials in 1992 and 1993. QTLs were detected via regression an alyses at multiple marker loci for each morphological trait. A total o f 41 markers were significantly associated with the traits examined. L arge additive effects were measured at many of these loci. QTLs for mu ltiple traits were detected on chromosomes 3 (TG74) and 4 (CT188), sug gesting the possible association of these chromosome segments with gen es controlling growth and development in tomato. These chromosomal reg ions were also associated with multiple morphological traits in a L. e sculentum x Lycopersicon pennellii cross. A total of 13% of the QTLs i dentified for traits common to both studies occupied similar map posit ions.