Avirulent mutants of Macrophomina phaseolina and Aspergillus fumigatus initiate infection in Phaseolus mungo in the presence of phaseolinone; levamisole gives protection.
To evaluate the role of phaseolinone, a phytotoxin produced by Macrophomina phaseolina, in disease initiation, three nontoxigenic avirulent mutants of the fungus were generated by UV-mutagenesis. Two of them were able to initiate infection in germinating Phaseolus mungo seeds only in the presence of phaseolinone. The minimum dose of phaseoli-none required for infection in 30% seedlings was 2 5 mg/ml. A human pathogen, Aspergillus fumigatus was also able to infect germinating seeds of P. mungo in the presence of 5 mg/ml concentration of phaseolinone. Phaseolinone seemed to facilitate infection by A. fumigatus, which is not normally phytopathogenic, by reducing the immunity of germinating seedlings in a nonspecific way. Levamisole, a non-specific immunopotentiator gave protection against infection induced by A. fumigatus at an optimum dose of 50 mg/ml. Sodium malonate prevented the effects of levamisole.
Sett
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Indian Institute of Chemical Biology, 4, Raja S C Mullick Road, Jadavpur, Calcutta 700 032, India.
Mishra
S K
SK
Siddiqui
K A
KA
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D001232:Aspergillus fumigatus / Q000235:genetics* / Q000472:pathogenicity; D004347:Drug Interactions; D007887:Fabaceae / Q000382:microbiology*; D007113:Immunity, Innate / Q000187:drug effects; D007978:Levamisole / Q000494:pharmacology*; D003904:Mitosporic Fungi / Q000235:genetics* / Q000472:pathogenicity; D009154:Mutation; D009183:Mycotoxins / Q000494:pharmacology*; D009284:Naphthols / Q000494:pharmacology*; D010935:Plant Diseases / Q000139:chemically induced / Q000382:microbiology*; D010946:Plants, Medicinal; D012639:Seeds / Q000382:microbiology
D000276:Adjuvants, Immunologic; D009183:Mycotoxins; D009284:Naphthols; D007978:Levamisole; C056401:phaseolinone