Maternal stress reduces the susceptibility of root-knot nematodes to Pasteuria penetrans

Authors: LIU, CHANG - University Of Florida; JI, PINGSHENG - University Of Georgia; Timper, Patricia - Patty

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2019
Publication Date: 7/29/2019
Citation: Liu, C., Ji, P., Timper, P. 2019. Maternal stress reduces the susceptibility of root-knot nematodes to Pasteuria penetrans. Journal of Nematology. 51:E2019-40. https://doi.org/10.21307/jofnem-2019-040.
DOI: https://doi.org/10.21307/jofnem-2019-040

Interpretive Summary: Pasteuria penetrans is a bacterium and a parasite of root-knot nematodes. Spores of Pasteuria attach to the cuticle of nematode juveniles and complete their life cycle within the adult female body. Infected females will be filled with spores and will be unable to produce eggs. Studies with water fleas and a related parasite Pasteuria ramosa showed that a poor maternal environment can lead to offspring resistant to the parasite. Therefore, we hypothesized that females of the peanut root-knot nematode raised under a stressed environment would produce offspring that were more resistant to Pasteuria. Females were exposed to a stressed environment created by crowding and low food supply, or a non-stressed environment and their offspring evaluated for spore attachment and infection by Pasteuria. No difference in spore attachment was observed between the two treatments. However, the infection rate of Pasteuria in the stressed treatment was significantly lower than that in the non-stressed treatment (8% vs. 18%). Mothers raised under stressed conditions appeared to produce more resistant offspring than did mothers raised under favorable conditions. Under stressful conditions, root-knot nematode mothers may provide their progeny with enhanced survival traits. In the field, when nematode populations are not managed, they often reach the maximum population that their host plant can support. This study suggests that when nematode crowding occurs, the next generation of root-knot nematodes may be more resistant to infection by Pasteuria.

Technical Abstract: Pasteuria penetrans is an obligate parasite of root-knot nematodes (Meloidogyne spp.). Endospores of P. penetrans attach to the cuticle of second-stage juveniles (J2) and complete their life cycle within the nematode female body. Infected females will be filled with spores and will be sterilized. Studies with Daphnia magna and its parasite Pasteuria ramosa showed that a poor maternal environment can lead to offspring resistant to P. ramosa. Therefore, we hypothesized that Meloidogyne arenaria females raised under a stressed environment would produce offspring that were more resistant to P. penetrans. Females were exposed to a stressed environment created by crowding and low food supply, or a non-stressed environment and their offspring evaluated for endospore attachment and infection by P. penetrans. No difference in spore attachment was observed between the two treatments. However, infection rate of P. penetrans in the stressed treatment was significantly lower than that in the non-stressed treatment (8% vs. 18%). Mothers raised under stressed conditions appeared to produce more resistant offspring than did mothers raised under favorable conditions. Under stressful conditions, M. arenaria mothers may provision their progeny with enhanced survival traits. In the field, when nematode populations are not managed, they often reach the carry capacity of their host plant by the end of the season. This study suggests that the next generation of inoculum may be more resistant to infection by P. penetrans.