Studies on the selective fungitoxicity of aliphatic amines |
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| Authors: | J W Eckert J L Smilanick B F Bretschneider |
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| Institution: | 1.Department of Plant Pathology,University of California,Riverside,USA |
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| Abstract: | A comparison of the uptake of simple (C1–C4) aliphatic amines byPenicillium digitatum revealed that the fungitoxicity of (?)sec-butylamine (?)SBA] was not due to its accumulation by hyphae since (+)SBA was accumulated to the same extent and methylamine, which showed negligible antifungal activity, accumulated to twice the level of SBA. Amines with a secondary alkyl structure were resistant to fungal metabolism, whereas primary amines were degraded to a significant extent byP. digitatum during a 4 h incubation period.(?)SBA accumulated in the fresh hyphae ofP. digitatum to a level 24 times higher than that in the culture medium containing 1 μmol ml?1; most of the SBA effluxed from the hyphae when transferred to fresh culture medium minus SBA. SBA did not accumulate when hyphae were incubated in N2 or in the presence of respiratory inhibitors. The absorption and accumulation of SBA is characteristic of active transport.Penicillium species and biotypes that are sensitive to SBA did not accumulate more (?)SBA than resistant fungi. SBA-resistant biotypes ofP. digitatum accumulated SBA to twice the level of SBA-sensitive biotypes, but did not accumulate pyruvate in the hyphae, which is characteristic of SBA-altered metabolism.No evidence was found to implicate exclusion or metabolic detoxification as mechanisms of SBA resistance. More probably, resistance involves cytoplasmic sequestration of SBA or low affinity of the biochemical target, pyruvic dehydrogenase. |
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