MAPPING OF QTLS INVOLVED IN NEMATODE RESISTANCE, TUBER YIELD AND ROOTDEVELOPMENT IN SOLANUM SP

A backcross population, derived from the cross (S. tuberosum x S. speg azzinii) x S. tuberosum was used to map QTLs involved in nematode resi stance, tuber yield and root development. Complete linkage maps were a vailable for the interspecific hybrid parent as well as the S. tuberos um parent, and interval mapping for all traits was performed for both. Additionally, the intra- and inter-locus interactions of the QTLs wer e examined. The Gro1.2 locus, involved in resistance to G. rostochiens is pathotype Ro1, that was previously mapped in the S. tuberosum x S. spegazzinii F-1 population, was located more precisely on chromosome 1 0. A new resistance locus, Gro1.4, also conferring resistance to G. ro stochiensis pathotype Ro1, was found on chromosome 3. Different allele s of this locus originating from both parents contributed to the resis tant phenotype, indicating multiallelism at this locus. No interlocus interactions were observed between these two resistance loci. For resi stance to G. pallida no QTLs were detected. One minor QTL involved in tuber yield was located on chromosome 4. Two QTLs involved in root dev elopment and having large effects were mapped on chromosomes 2 and 6 a nd an epistatic interaction was found between these two loci.