ABSTRACT
Slime mold species in the genus Dictyostelium are considered to have a close relationship with non-parasitic nematodes; they are sympatric in soils and can exhibit interspecific competition for food. We investigated whether this relationship extends to a plant-parasitic nematode that is active in the rhizosphere and has broad host specificity, damaging crops worldwide. Using a novel assay to examine the interaction between the cellular slime mold, Dictyostelium discoideum, and the plant-parasitic nematodes, Meloidogyne spp., we found that cellular slime molds can repel plant parasitic nematodes. Specifically, the repulsion activity was in response to chemical compounds released by cellular slime mold fruiting bodies. Under laboratory conditions, these soluble chemical extracts from fruiting bodies of D. discoideum showed repulsion activity strong enough to protect plant roots. The fruiting body cell extracts repelled but were not toxic to the plant-parasitic nematodes.
Subject(s)
Antiparasitic Agents/chemistry , Antiparasitic Agents/pharmacology , Dictyostelium/chemistry , Dictyostelium/physiology , Plant Diseases/parasitology , Tylenchoidea/drug effects , Tylenchoidea/pathogenicity , Animals , Dictyostelium/growth & development , Fruiting Bodies, Fungal/chemistry , Fruiting Bodies, Fungal/physiology , Lotus/drug effects , Lotus/parasitology , Plant Diseases/prevention & control , Plant Roots/drug effects , Plant Roots/parasitology , Soil Microbiology , Sympatry/physiologyABSTRACT
Fatty acids are fundamental cellular components, and provide essential building blocks for membrane biosynthesis. Although the use of gene knockout mutants is a robust method for examining the function of specific cellular metabolic networks, fatty acid synthase knockout mutants are extremely difficult to isolate. In the Dictyostelium discoideum genome, we found two putative fatty acid synthase genes, and we created a knockout mutant for one of them to examine the physiological consequences. In this study, we found that a continuous fatty acid supply was necessary for normal development, and the fatty acid synthase knockout mutant showed severe developmental delay. This developmental defect was corrected in chimeras composed of wild type cells and knockout mutant cells (3:7, respectively). The knockout mutant also showed aberrant expression of fatty acid biosynthesis genes. These results showed that D. discoideum needs correct fatty acid synthesis for normal development.
