RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS OF LOCI ASSOCIATED WITH DISEASE RESISTANCE GENES AND DEVELOPMENTAL TRAITS IN PISUM-SATIVUM L

An F-2 population of pea (Pisum sativum L.) consisting of 174 plants w as analysed by restriction fragment length polymorphism (RFLP) and ran dom amplified polymorphic DNA (RAPD) techniques. Ascochyta pisi race C resistance, plant height, flowering earliness and number of nodes wer e measured in order to map the genes responsible for their variation. We have constructed a partial linkage map including 3 morphological ch aracter genes, 4 disease resistance genes, 56 RFLP loci, 4 microsatell ite loci and 2 RAPD loci. Molecular markers linked to each resistance gene were found: Fusarium wilt (6 cM from Fw), powdery mildew(11 cM fr om er) and pea common Mosaic virus (15 cM from mo). QTLs (quantitative traits loci) for Ascochyta pisi race C resistance were mapped, with m ost of the variation explained by only three chromosomal regions. The QTL with the largest effect, on chromosome 4, was also mapped using a qualitative, Mendelian approach. Another QTL displayed a transgressive segregation, i.e. the parental line that was susceptible to Ascochyta blight had a resistance allele at this QTL. Analysis of correlations between developmental traits in terms of QTL effects and positions sug gested a common genetic control of the number of nodes and earliness, and a loose relationship between these traits and height.