ANALYSIS OF DNA FROM A BETA-PROCUMBENS CHROMOSOME FRAGMENT IN SUGAR-BEET CARRYING A GENE FOR NEMATODE RESISTANCE

We have begun to apply techniques for the preparation and anaylsis of large DNA segments from sugar beet (Beta vulgaris) addition lines carrying a mitotically stable chromosome fragment from B. procumbens that confers monogenic resistance to the nematode Heterodera schachtii, with a view towards isolating the resistance gene. DNA probes specific for this chromosome fragment were selected, and various methods for cloning genome-specific fragments, including probes from megabase DNA separated in pulsed-field slab gels, are compared. Probes that display high homology to B. procumbens have been used for hybridization of a representative genomic library and for initial step in mapping the chromosome fragment via pulsed-field gel electrophoresis after restriction with infrequently cutting enzymes. Our data indicate that DNA molecules from the entire chomosome fragment can be separated from protoplast DNA lysates. © 1990 Springer-Verlag.