RANDOM AMPLIFIED POLYMORPHIC DNA MARKERS IN SWEET-POTATO INFECTED WITH FUSARIUM-LATERITIUM

DNA isolated from Fusarium lateritium Nees: Fr.-infected 'Jewel' sweet potato [Ipomoea batatas (L.) Lam.] plants was compared to F. lateritiu m-free 'Jewel' plants for differences in random amplified polymorphic DNA (RAPD) marker products, Differences in RAPD marker products mere d etected, Amplified DNA isolations from F. lateritium-infected 'Jewel' plants generated additional, unique DNA fragments not found in amplifi ed DNA isolations of F. lateritium-free 'Jewel' plants. These unique a mplified DNA fragments mere consistent with those obtained from amplif ied DNA isolations of the F. lateritium isolate, 91-27-2, used for ino culation. We found that F. lateritium DNA successfully competes with s weetpotato DNA in the polymerase chain reaction for priming sites in a 3:1 ratio of sweetpotato DNA to F. lateritium DNA. Our results indica te the importance of avoiding plant material infested with pathogens t o avoid spurious marker bands.