FUSARIUM-GRAMINEARUM DNA INDUCES VARIATIONS IN SOIL-BORNE FUSARIUM-CULMORUM PLANT PATHOGEN

Fusarium culmorum protoplasts, incubated with DNA obtained from Fusarium graminearum, were regenerated individually into cultures. A number of isolates obtained from these incubations demonstrated dramatic growth and physiological differences when compared with cultures of the parent organisms developed from protoplasts which were not treated with DNA. The differences include spore morphology and distinct patterns of growth effected by temperature, and media. The radial growth of variants ranged from 17 mm to 38mm in 6 days at 27-degrees-C on malt agar. At 13-degrees-C and 15-degrees-C two selected isolates demonstrated significantly greater radial growth than the parent cultures. These two variants themselves grew at different rates at 15-degrees-C and 20-degrees-C in a peptone-yeast extract liquid medium. The average dimensions (length x width) of the macroconidia from cultures of these variants were smaller (165-mu-174-mu) compared to those of the parents, F. culmorum (254-mu) and F. graminearum (225-mu). The significance of these observations are discussed in relation to Fusarium taxonomy and the biology of the organisms.