Development of a PCR-based selection assay for root-knot nematode resistance (Rmc1) by a comparative analysis of the Solanum bulbocastanum and S-tuberosum genome

A PCR-based assay has been developed for marker assisted selection of root- knot nematode resistance (Rmc1) in potato. To this end, a comparative genom e analysis was carried out between Solanum bulbocastanum and S. tuberosum t o identify PCR-based chromosome 11 alleles linked to Rmc1. The use of co-mi grating AFLP markers, obtained by using primer combinations previously appl ied for AFLP analysis of the S. tuberpsrm genome, failed to align the AFLP map of the S. bulbocastanum genome with the S. tuberosum map. Apparently, t he S. bulbocastanum genome is genetically too distantly related to the S. t uberosum genome for this type of analysis. Cleaved amplified polymorphic se quence (CAPS) markers were more readily applied for a comparative analysis within the region of interest. Rmcl could be localized within a 4 cM interv al between markers CT182 and M39b. It is demonstrated that the resistance s pectrum of Rmc1 includes not only Meloidogyne chitwoodi and the related spe cies M. fallax but also a genetically distinct population of M. hapla. The cost-efficiency of the CAPS markers applied for Rmc1 renders this approach as an attractive alternative for screening large segregating populations of potato for root-knot nematode resistance.