VIRULENCE OF Fusarium verticilliodes (SACC.) NIRENBERG (G) ISOLATES ON MAIZE PLANTS ASSOCIATED WITH FUMONISINS PRODUCTION

Abstract

Fusarium verticilliodes (Sacc.) Nirenberg (G) is a well known phytopathogenic fungus capable to infect a wide range of plants including maize. In addition; its toxic metabolites fumonisin (FB1 and FB2) are associated with Equina Leukoencephalo Malacia and induced hepatotoxic and carcinogenic effects in animals. Twenty two isolates of F. verticilliodes obtained from corn samples and grown on Barley medium, were added to sterile soil two weeks before sowing maize grains to test their ability to cause corn seedling damping-off. Thirteen isolates caused pre-emergence damping-off, and two of them were significant. In addition one F. verticilliodes isolate was significantly affecting post emergency and four isolates exhibited the highest disease index. F. verticilliodes isolates which caused significant pre and post emergence damping-off as well as disease index were found to be fumonisin producers. Fourteen out of twenty two detached and moistened maize leaves showed necrotic lesions when they inoculated by F. verticilliodes spore suspensions. Further more the crude extracts of the tested F. verticilliodes isolates showed leaf lesions when they were spotted on the moisted maize leaf cuts, in addition to FB1 standard. Twelve of the pathogenic F. verticilliodes isolates produced fumonisins (eight; FB1 and four; FB1 & FB2); whereas fumonisins could not been detected in only two of the pathogenic isolates according to TLC.. These results suggest the great role of fumonisins that may be played as a virulence factor of F. verticilliodes on maize.