Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 9, 1996
Publication Date: N/A
Interpretive Summary: The soilborne plant pathogen Fusarium oxysporum causes wilt of many different plant species. The limited host range of many isolates of F. oxysporum makes them good candidates for use as mycoherbicides in situations where their hosts are undesirable. Before mycoherbicides can be used, factors influencing their host range and pathogenicity must be determined. F. oxysporum can produce toxins which elicit symptoms of disease in plants, but their importance in disease development and host range determination is unclear. This report describes the production of a 24 kDa protein by isolates of F. oxysporum pathogenic on plant species including Erythroxylum coca. The protein induces ethylene production and necrosis in leaves of many different plant species. The influence of the protein on disease development remains to be determined. An improved understanding of how Fusarium oxysporum causes disease will lead to better ways to control the diseases it causes as well as allow its exploitation by agriculturists as a biocontrol agent for undesirable plants.
Technical Abstract: A 24 kDa protein which elicits ethylene production and necrosis in leaves of Erythroxylum coca var. coca was purified from culture filtrates of an isolate of F. oxysporum Schlechtend:Fr. pathogenic to E. coca var. coca. Antisera to the denatured 24 kDa protein detected 2.5 ng of the 24 kDa protein on western blots at dilutions of 1:1 X 105. When the 24 kDa protein was precipitated with TCA, a ladder of multimeric forms of the 24 kDa protein were separated by SDS gel electrophoresis which were recognized by antisera to the denatured 24 kDa protein. Several of the breakdown products of the 24 kDa protein produced by heating were recognized by antisera to the denatured 24 kDa protein. Among the seven Fusarium species tested, only F. oxysporum, F. acuminatum Ellis and Kellerm. and F. avenaceum (Fr.:Fr.) Sacc. isolates produced an antigenically related 24 kDa protein in culture filtrates. The antisera cross-reacted with a 24 kDa protein on western blots of culture filtrates from six of seven F. oxysporum formae speciales tested. The antisera failed to cross-react with proteins in culture filtrates of seven non-Fusarium fungal isolates. The 24 kDa protein induced ethylene production and/or necrosis in a wide variety of plant species but did not produce measurable responses in members of the Monocotoledonae.