Resolution of quantitative traits into Mendelian factors by using a complete linkage map of restriction fragment length polymorphisms

Abstract

The conflict between the Mendelian theory of particulate inheritance and the observation of continuous variation for most traits in nature was resolved in the early 1900s by the concept that quantitative traits can result from segregation of multiple genes, modified by environmental effects. Although pioneering experiments showed that linkage could occasionally be detected to such quantitative trait loci (QTLs), accurate and systematic mapping of QTLs has not been possible because the inheritance of an entire genome could not be studied with genetic markers. The use of restriction fragment length polymorphisms (RFLPs) has made such investigations possible, at least in principle. Here, we report the first use of a complete RFLP linkage map to resolve quantitative traits into discrete Mendelian factors, in an interspecific back-cross of tomato. Applying new analytical methods, we mapped at least six QTLs controlling fruit mass, four QTLs for the concentration of soluble solids and five QTLs for fruit pH. This approach is broadly applicable to the genetic dissection of quantitative inheritance of physiological, morphological and behavioural traits in any higher plant or animal.

Genetic specification of life span and self-fertility in recombinant-inbred strains of Caenorhabditis elegans

“…food assimilation). Further studies will entail larger numbers of RI strains and the use of multiple linked RFLPs to localize QTLs (Paterson et a!., 1988;Lander & Botstein, 1989) that specify life span and/or agespecific fertility.…”

Use of Arabidopsis recombinant inbred lines reveals a monogenic and a novel digenic resistance mechanism to Xanthomonas campestris pv campestris

“…To provide a comparative analysis of resistance scores among experiments, the disease scores for the RI lines were transformed to the fraction of chlorosis unique to Ler using the calculation of (X-Col)/(Ler-Col) where X equals the mean disease score for the RI line, Col equals the mean disease score for Col, and Ler equals the mean disease score for Ler. Linkage analysis was performed using the MAPMAKER version 2.0 for the Macintosh (Lander et al, 1987) provided by S. Tingey (Dupont, Wilmington, DE) and the MAPMAKER QTL program (Paterson et al, 1988). Genetic distance on the RI map is reported in cM using the Kosambi mapping function and is from the Arabidopsis genetic map (Anderson, 1996).…”

“…Some F 8 RI lines containing the Ler alleles of RXC2 (rxc2-2) were resistant to X. c. campestris, suggesting the presence of additional resistance loci and thus confirming the model predicted from the F 1, F 2, and BC1 segregation data. To detect these additional loci, the disease resistance scores and segregration data for 76 molecular markers were analyzed using the MAPMAKER QTL program, which, in contrast to MAPMAKER version 2.0, allows for detection of multiple loci within a segregating population that contribute to a phenotype (Paterson et al, 1988). Although MAPMAKER QTL was not designed for analysis of RI populations, the program has been shown to be robust enough to use with these data (Wang et al, 1994).…”

The tomato genome: implications for plant breeding, genomics and evolution

“…This aided the construction of an RFLP (restriction fragment length polymorphism) linkage map [44,45]. The resulting comprehensive molecular linkage map enabled breeders to identify quantitative trait loci (QTLs) leading to an understanding of the genetic basis of numerous quantitative traits [46]. The Solanaceae Genomics Network website provides extensive information on the available tomato genetic and genomic resources [47].…”