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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #60022
Title: VIRULENCE, LEGUME HOST SPECIFICITY, AND GENETIC RELATEDNESS OF ISOLATES OF FUSARIUM OXYSPORUM FROM RED CLOVER

Author
item VENUTO, BRADLEY - LOUISIANA STATE UNIV
item Smith, Richard
item GRAU, CRAIG - UNIV OF WISCONSIN-MADISON

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Soil-borne disease organisms like Fusarium oxysporum infect roots of perennial forage legumes and cause root decay leading to premature death of the plants which leads to reduced perenniality. This study was designed to investigate the reaction of different forage legumes to the Fusarium disease organism in an effort to identify plants resistant to the organism. .This resistance would improve persistence of the legumes, thus extending the life of these species in pasture and hay fields and reduce the frequency of re-establishment and reduce user costs. We determined that red clover, white clover, alfalfa and trefoil react differentially to different isolates of the organism. Also, we observed that the genetics of the organism could not predict the reaction on the plant species. Our results suggest that to develop red clover populations resistant to the organism we have to identify plants resistant to several isolates of the organism and intercross these resistant plants to develop a new population

Technical Abstract: Fusarium oxysporum is the most prevalent fungal pathogen recovered from symptomatic red clover (Trifolium pratense) plants in Wisconsin and contributes to stand loss and reduced productivity. Three field isolates and 44 single-condium isolates of F. oxysporum were recovered from red clover plants with vascular wilt symptoms and assessed for virulence, host specificity, and source of variation in host reaction. In addition, genetic relatedness of selected isolates was determined utilizing vegetative compatibility groupings (VCG). Twenty-one populations of red clover, two populations of alfalfa (Medicago sativa), and one population each of alsike clover (T. hybridum), ladino clover (T. repens) and birdsfoot trefoil (Lotus corniculatus) were tested for reaction to isolates of F. oxysporum. Host populations differed significantly in reaction to specific field isolates or single-conidium isolates. Isolates differed significantly in their ability to elicit reaction both among and within host species. VCGs were not useful in predicating host reaction since isolates from distinct groupings elicited similar host reaction. Reaction of red clover to F. oxysporum is attributable to genetic diversity in isolates virulence as well as variation within the host population for resistance.