Some accessions of Lycopersicon pennellii, a wild relative of the tomato Lycopersicon esculentum, are resistant to a number of important pests of cultivated tomato due to the accumulation of acylsugars, which constitute 90% of the exudate of type-IV trichomes in L. pennellii LA716. An interspecific F2 population, created by the cross L. esculentum x L. pennellii LA 716, was surveyed for acylsugar accumulation and subjected to RFLP/QTL analysis to determine the genomic regions associated with the accumulation of acylglucoses, acylsucroses, and total acylsugars, as well as with acylglucoses as a percentage of total acylsugars (mole percent acylglucoses). Data were analyzed using MAPMAKER/QTL with and without a log10 transformation. A threshold value of 2.4 (default value for MAPMAKER/QTL) was used, as well as 95% empirically derived threshold values. Five genomic regions, two on chromosome 2 and one each on chromosomes 3, 4 and 11, were detected as being associated with one or more aspects of acylsugar production. The L. esculentum allele is partially dominant to the L. pennellii allele in the regions on chromosomes 2 and 11, but the L. pennellii allele is dominant in the region on chromosome 3. Throughout this study, we report the comparative effects of analytical methodology on the identification of acylsugar QTLs. Similarities between our results and published results for the genus Solanum are also discussed.

UDP-glucose (UDP-ClcFoliar glandular trichomes of wild tomato (Lycopersicon pennellii) secrete a complex mixture of polar lipids composed of 2,3,4-tri-O-acylglucose esters of short-and medium-chain-length branched-and straight-chain fatty acids (Fobes et al., 1985;Burke et al., 1987). These Glc esters are responsible for the broad-spectrum insect resistance of L. pennellii (Goffreda et al., 1989; Hawthorne et al., 1992;Liedl et al., 1995). The cultivated tomato (Lycopersicon esculentum) lacks the ability to accumulate sugar esters (Fobes et al., 1985), and transfer of this trait could significantly reduce the impact of insect pests on this and other crop species (Mutschler et al., 1993 The degree to which sugar polyester biosynthesis dominates carbon flux in this species (secreted 2,3,4-tri-Oacylglucoses represent more than 20% of leaf dry weight) makes this an attractive system to study biosynthesis and metabolic control. Biosynthesis of 2,3,4-tri-O-acylglucoses in L. pennellii exhibits severa1 nove1 qualities (Fig.

Lycopersicon pennellii, a wild relative of the tomato, L. esculentum, is resistant to a number of important pests of cultivated tomato due to the accumulation of acylsugars, which constitute 90% of L. pennellii LA716 type IV trichome exudate. An interspecific F2 population created by crossing L. esculentum × L. pennellii was surveyed for acylsugar accumulation and subjected to RFLP analysis to determine the genomic regions associated with the levels of acylglucoses, acylsucroses, and total acylsugars accumulated, and glucose as a percentage of total acylsugars. Data was analyzed using MAPMAKER with and without log10 transformation and using a threshold of either 2.4 (default value for MAPMAKER) or ones calculated according to the Permutation-based Estimated Threshold (PET) method. Genomic regions were identified for each of the traits studied. Effects of analytical method on identification of QTLs, similarities between these results and results published for the genus Solanum, and similarities between these results and the regions transferred by a breeding program selecting for acylsugar production are discussed.