Screening of the naturally nematicidal compounds against plant parasitic nematode Pratylenchus penetrans Mechanisms

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In the course of a screening search for new nematicidal compounds among the fungal metabolites, using bioassay method with a root-lesion nematode Pratylenchus penetrans, suitable for developing new nematicides and new lead compounds, I found the presence of active compounds in the metabolites of Penicillium bilaiae Chalabuda, Penicillium cf. simplicissimum, and an unidentified Aspergillus sp.Biosassay-guided fractionation led to the isolation of four active compounds,2,6-pyridinedicauboxylic acid,6-methoxypicolinic acid, p-hydroxyacetophenone and a new compound named pratynolene from the culture filtraste of Penicillium bilaiae Chalabuda. Three active compounds together with a related but inactive compound were also isolated from the mycelial mats of Penicillium cf.simplicissimum. Four curvuralin analogs were obtained from the culture filtrate and mycelial mats,although two of them were inactive.From these results together with bioassays with rice and lettuce seedlings,the following facts became clear.1) Active compounds are present in the culture filtrate or mycelial mats.2) Some of the nematicidal compounds shows phytotoxic activity.3) Some compounds have selectivity such as a compound shows nematicidal activity against P.penatrans but sit is inactive against C. elegance.