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.
Botanical Institute of the Ludwig Maximilians University Munich, Menzinger Straße 67, 8000, Munich 19, FRG.
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