1. Studies on the inhibition of plant pathogenic fungi by cyclohexylamine and spermidine analogues
- Author
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Mackintosh, Caroline Anne
- Subjects
580 ,Botany - Abstract
The potential inhibitory activity of several compounds against plant pathogenic fungal growth was studied. Prevention of growth was hypothesised to occur by the inhibition of polyamine biosynthesis and/or an effect on cellular functions associated with spermidine, the predominant polyamine in fungi. The spermidine synthase inhibitor, cyclohexylamine (CHA), and the spermidine analogue, norspermidine, demonstrated protective, eradicant and systemic activity against a range of plant pathogenic infections of host plants: broad bean rust and chocolate spot, barley and apple powdery mildew, and potato late blight. For example, both 2.0 mM CHA and 2.0 mM norspennidine, applied pre inoculation, reduced powdery mildew infection of barley by 88 %. CHA and norspermidine were equally effective although apple powdery mildew and potato late blight infections were slightly more responsive towards norspermidine than CHA treatment. Against bean rust and barley powdery mildew, little increased efficacy was afforded by increasing inhibitor concentrations from 0.5 mM to 2.0 mM. Higher concentrations were, however, more effective against the other pathogenic infections examined. Pre inoculation treatments tended to be more effective than post inoculation applications of the inhibitors, although the reason for this is unclear as microscopic examination of bean rust spores and developing germlings on bean leaves found little difference between the treated leaves and the untreated control, suggesting the compounds acted on later stages of fungal development. CHA and norspermidine were also effective against powdery mildew infection of spring barley in the field. The compounds were as effective as a commercially available fungicide in reducing disease. Neither the commercial fungicide nor the inhibitors caused any increase in yield over the untreated control, although this may have been the result of additional environmental pressures. The study therefore showed that CHA and spermidine analogues possessed both antifungal and fungicidal activity against a range of plant pathogens. Although differences in in vivo and in vitro studies exist, perturbation of polyamine biosynthesis was unlikely to account for such activity of the compounds. The compounds were most likely exerting their effects via some other cellular function related to polyamines.
- Published
- 1997
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