Characterisation of an endospore population of Pasteuria that adheres to the plant-parasitic nematode Heterodera schachtii

Selected strains of Pasteuria species from the endospore-forming Gram-positive bacteria group have the potential to be developed into control agents for plant-parasitic nematodes. If Pasteuria is to be deployed successfully as a control agent, endospores of the bacterium initially have to adhere to the cuticle of the infective juvenile. Studies of the bacteria isolated from root-knot nematodes have suggested that collagen-like fibres on the endospore surface interact with a cuticle receptor on the second-stage juvenile through a host specific 'Velcro-like' mechanism. However, very little is known regarding the biochemical nature of the mechanism in Pasteuria strains isolated from cyst nematodes. Here, using several polyclonal antibodies raised to whole endospores and to synthetic collagenlike peptides, we compare two Pasteuria populations, one a strain from a root-knot nematode, Meloidogyne javanica, and another from cowpea cyst nematode, Heterodera cajani. We demonstrate that there is differential adhesion of endospores to the beet cyst nematode H. schachtii and that the sugar moieties on the endospore surface may protect the collagen-like fibres on the endospore from proteolytic digestion and be involved in the endospore's specificity.