The Utilization of RAPD to Obtain Markers Linked with Nitrogen Fixation in Common Bean (Phaseolus vulgaris)

Abstract

A breeding project for nitrogen fixation in common bean has been carried out, utilising the cross A295 and WBR2255. Families with extreme expression of nitrogen fixation capacity were identified. Initially, 490 RAPD primers were used in order to find polymorphism between the parents. From 4780 loci tested, 5.6% were polymorphic. Using only the polymorphic primers, and DNA from the 10 highest and 10 lowest genotypes in F2 and F5 generations a Bulk Segregant Analysis was performed to identify markers genetically linked to nitrogen fixation capacity. The BSA was not an efficient method to detect such linkages. However, better results were obtained when testing separatelly the individuals pooled in the bulks. From 390 loci tested, 67 were polymorphic, 18 showed differences in frequency between individuals with high and low nitrogen fixation capacity. Six markers were chosen for testing on the entire population obtained by Single Seed Descent. Five were linked with traits indicative of nitrogen fixation, two independently and 3 linked. The percentage of trait variation which was accounted for by the markers were however low, ranging from 3.01 to 4.99%.