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Verticillium dahliae Kleb. is a cosmopolitan vascular wilt plant pathogen. With a few exceptions, most isolates of the fungus have a broad host range. Differentiation of fungal strains based on morphologic diversity or physiologic races based solely on host/pathogen interaction has been relatively ineffective. The more recent use of vegetative or heterokaryon compatibility groups using auxotrophic mutants to distinguish strains of the fungus has proven to be a more effective tool. Problems of assigning strains to a specific vegetative compatibility group (VCG) due to weak complementation or overlapping group assignment have been reported. The use of differential isozyme profiles to distinguish strains of V. dahliae is presently being investigated. Forty-one isolates of the fungus representing VCG-1, VCG-2, and VCG-4 are being screened using six enzyme systems. Glutamate dehydrogenase (E. C. 1.4.1.4), aspartate aminotransferase (E.C. 2.6.1.1), and alanine aminotransferase (E.C. 2.6.1.2) are useful in confirming VCG assignments in most cases. A subgroup of the VCG-4 group was detected with NADP-glutamate dehydrogenase profiles (E.C.1.4.1.3 and E.C. 3.5.1.1) and superoxide dismutase (E.C. 1.15.1.1) are two other enzyme systems that are undergoing testing at this time. Preliminary data indicate a possible role for isozyme profiles in clarifying VCG assignments. Additional Screening of strains, using more enzyme systems, and elaboration of the proper growth conditions favorable to enzyme expression are needed. |
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©National Cotton Council, Memphis TN |
Document last modified Sunday, Dec 6 1998
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