Identification of DNA probes that reveal polymorphisms among closely related Phaseolus vulgaris lines

Abstract

Analyses of genetic diversity within populations could be of great benefit to plant genetic resources conservation. In order to identify genetic markers that are variable within populations, the genome of Phaseolus vulgaris was screened with several DNA sequences in order to identify hypervariable sequences. Polymorphisms were observed between Middle American and Andean cultivars using the protein III tandem repeat of the M13 phase and the 33.15 human minisatellite. Extensive differences were observed when the DNA of two divergent lines—BAT93 and Jalo EEP558, of Middle American and Andean origin, respectively—were digested with HinfI, TaqI, HaeIII and hybridized with the 33.15 human minisatellite. Similarly, numerous polymorphisms were observed when the M13 protein III tandem repeat region was hybridized with TaqI digests of these cultivars. Polymorphism was also detected among sister lines of two F6 backcross materials involving Middle American and Andean lines when genomic DNA was digested with TaqI and hybridized with M13 tandem repeat region. In addition, polymorphism was observed among Porrillo cultivars that resulted from selection within a single landrace population. 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 cultivars. Ribosomal DNA also hybridized to several polymorphic bands on TaqI and EcoRI genomic Southern blots of the F6 backcross material. Only one polymorphism was observed with EcoRI-digested genomic DNA of BAT93 and Jalo EEP558 was hybridized with microsatellite (GACA)4. This probe 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 probes to detect within-population variability in common bean.