QTL analysis of acylsugar accumulation and related traits using intraspecific populations of Lycopersicon pennellii

Accessions of Lycopersicon pennellii display a high level of resistance to several insect pests. This resistance is conferred by acylsugars exuded by type IV glandular trichomes. Acylsugars are complexes comprised of a sugar moiety (glucose or sucrose) esterified to several possible fatty acid constituents. Intraspecific populations between L. pennellii LA716 and L. pennellii LA1912, an accession with low-level acylsugar accumulation, were created to study the inheritance of type IV trichome density, acylsugar levels, percentage of acylsugars that are acylglucoses, and fatty acid profile. The F{dollar}sb2{dollar} population was subsequently used to identify genomic regions associated with these traits.; Percent acylglucoses was found to be largely controlled by a single locus near TG549 on chromosome 3. One locus on chromosome 10 showed significant associations with acylsugar levels. In addition, one locus on chromosome 4 showed significant associations with leaf area.; The relative proportions of nine fatty acids were found to segregate in the intraspecific F{dollar}sb2{dollar} population. Significant associations were detected at six loci for these traits. Combined, these QTLs explain 23-60% of the variance observed for each constituent. The percentage of iso-branched fatty acids with even carbon chain length was found to be primarily determined by a single locus near TG117 on chromosome 8. This QTL is likely to contain gene(s) in the biosynthetic pathway for 3-methylbutanoate downstream of the precursor for 2-methylpropanoate.; Studies of acylsugar accumulation using interspecific and intraspecific F{dollar}sb2{dollar} populations have one parent in common from Lycopersicon pennellii LA716. This allows for the comparison of map construction and QTL detection using interspecific versus intraspecific populations. More markers show aberrant segregation in the interspecific population. These markers are distributed in seven large regions. Most of the skewed markers in the intraspecific population are linked to the S-locus conferring self-incompatibility. A higher recombination frequency is observed in the intraspecific population on chromosomes 3, 6, 10 and 11, causing the overall distribution of recombination events to differ between the two populations. The probable effects of differences in map construction between interspecific and intraspecific populations on the identification of QTLs are discussed.