IDENTIFICATION OF DNA PROBES THAT REVEAL POLYMORPHISMS AMONG CLOSELY-RELATED PHASEOLUS-VULGARIS LINES

Analyses of genetic diversity within populations could be of great ben efit to plant genetic resources conservation. In order to identify gen etic markers that are variable within populations, the genome of Phase olus vulgaris was screened with several DNA sequences in order to iden tify hypervariable sequences. Polymorphisms were observed between Midd le American and Andean cultivars using the protein III tandem repeat o f the M13 phase and the 33.15 human minisatellite. Extensive differenc es were observed when the DNA of two divergent lines - BAT93 and Jalo EEP558, of Middle American and Andean origin, respectively - were dige sted with HinfI, TaqI, HaeIII and hybridized with the 33.15 human mini satellite. Similarly, numerous polymorphisms were observed when the M1 3 protein m tandem repeat region was hybridized with TaqI digests of t hese cultivars. Polymorphism was also detected among sister lines of t wo Fg backcross materials involving Middle American and Andean lines w hen genomic DNA was digested with TaqI and hybridized with M13 tandem repeat region. In addition, polymorphism was observed among Porrillo c ultivars that resulted from selection within a single landrace populat ion. Whereas only one isozyme difference had been observed previously among the Porrillo cultivars, eleven restriction fragments detected by the M13 protein III tandem repeat sequence differentiated these culti vars. Ribosomal DNA also hybridized to several polymorphic bands on Ta qI and EcoRI genomic Southern blots of the Fg backcross material. Only one polymorphism was observed with EcoRI-digested genomic DNA of BAT9 3 and Jalo EEP558 was hybridized with microsatellite (GACA)(4). This p robe might be useful in ascertaining relationships at the species and subspecies level, and as a marker in mapping studies. Our results show that both the human 33.15 minisatellite and M13 should be useful prob es to detect within-population variability in common bean.