Maternal Stress Reduces the Susceptibility of Root-Knot Nematodes to Pasteuria Penetrans

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 provide their progeny with enhanced survival traits. In the field, when nematode populations are not managed, they often reach the carrying 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.

Microbial landscapes of the rhizosphere soils and roots of Luffa cylindrica plant associated with Meloidogyne incognita

“…It appears to be a widespread bacterium (present at rhizosphere soils and plant roots) that plays a protective role from plant pathogenic infection. Some species of genera Geobacillus and Pasteuria in rhizosphere soils or plant roots show insecticidal or nematicidal activity, such as G. thermoglucosidasius and P. penetrans ( Liu et al, 2019 ; Siddharthan et al, 2022 ). Both genera were not changed at rhizosphere soils but significantly increased in the infected roots, especially genus Pasteuria .…”