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Poster: Biology & Disease Mgmt: Nematology


Influence of root exudates and soil on attachment of Pasteuria penetrans to Meloidogyne arenaria.
C. LIU (1), P. Timper (2) (1) University of Georgia, U.S.A.; (2) USDA ARS, U.S.A.

Pasteuria penetrans is a widely distributed endospore-forming bacterium which is a hyperparasite of Meloidogyne spp. Previous research showed that root exudates can reduce attachment of P. penetrans to Meloidogyne arenaria. The objective of this study was to determine if soil microorganisms modify the effect of root exudates on attachment of P. penetrans spores to M. arenaria. The following treatments were set up in both sand and clay soil: natural soil with a plant, sterilized soil with a plant, and natural soil without plant. For treatments with a plant, 1-month-old eggplant seedlings were used. All treatments were incubated in greenhouse for 3 days, and soil solutions were obtained by vacuum filtering saturated soil. Controls included phosphate-buffered saline (PBS) as well as root exudates in water. Second stage juveniles (J2) were incubated in 5 ml of different solutions for 6 h, rinsed and incubated in PBS for another 6 h with 105 P. penetrans spores. Compared to J2 incubated in PBS, attachment was significantly reduced when root exudates were present, with root exudates having a greater effect on attachment in sand than in clay. Spore attachment was always higher in clay than in sand solutions. Root exudates reduced spore attachment more in sterilized soil than in natural soil. The presence of microorganism and chemical composition of different soils may interact with root exudates to affect endospore attachment.