Antagonistic role of the microbiome from a Meloidogyne hapla-suppressive soil against species of plant-parasitic nematodes with different life strategies

Abstract

SummaryIn certain soils populations of plant-parasitic nematodes (PPN) decline. Understanding this effect may open up environmentally friendly management options. We identified such a suppressive soil containing virtually no PPN. Inoculated Meloidogyne hapla declined in this soil more than in a control soil and reproduction on tomato was reduced. The extracted soil microbiome alone decreased root invasion of second-stage juveniles (J2) and progeny as well as the native soil. We tested the antagonistic potential against PPN that differ in life strategies. The microbiome was most suppressive against two populations of M. hapla and one population of Pratylenchus neglectus, and least suppressive against M. incognita and the ectoparasite Hemicycliophora conida. In a split-root system with M. hapla, plant-mediated but not direct effects of the microbiome significantly reduced root invasion of J2, while direct exposure of M. hapla to the microbiome significantly affected reproduction. Overall, both plant-mediated and direct effects of the microbiome were responsible for the soil suppressiveness against M. hapla.

Microbes Attaching to Endoparasitic Phytonematodes in Soil Trigger Plant Defense Upon Root Penetration by the Nematode

“…However, previous studies mainly focused on the subtle differences in attached microbiota among different nematode stages or species and in different soils (Adam et al, 2014b;Elhady et al, 2017). Recently, we demonstrated that the soil microbiomes from a glasshouse at Geisenheim University reduced performance of M. hapla on tomato plants, while a splitroot experiment revealed the contribution of microbially triggered ISR to this phenomenon (Topalović et al, 2020). In addition, we isolated bacterial strains from the cuticle of M. hapla and Pratylenchus penetrans, showing their antagonistic activity, but the ability of nematode-attached bacteria to induce systemic resistance in plants has not yet been investigated .…”

“…One of the soils that we used for the J2 incubation to isolate attached microbes was obtained from a glasshouse of Geisenheim University, in the southeastern part of Germany. Remarkably, the extracted microbiomes from this soil suppressed performance of two endoparasitic nematode species, M. hapla and Pratylenchus neglectus, on tomato plants (Topalović et al, 2020). In a split-root experiment with M. hapla, the microbiomes reduced nematode invasion by ISR in plants, while the progeny was reduced by ISR and a direct antagonism.…”

“…To allow microbial attachment to nematodes, the M. hapla J2 were incubated in soil suspensions of a M. hapla-suppressive soil from Geisenheim (sandy clay soil with 2.7% humus, pH 7.4, 49°59'01" N, 7°57'25.5" E; Topalović et al, 2020). The soil was sieved through a 1 mm sieve and 30 g of sieved soil was blended with 120 ml of sterile tap water (10 g of soil with 2 × 20 ml) for 1 min at a high speed (Stomacher ® 80, LAB SYSTEM).…”

Plants and Associated Soil Microbiota Cooperatively Suppress Plant-Parasitic Nematodes

“…Most often, the united efforts of more than one mode of action are employed by soil microbiota in nematode suppression. Topalović et al (2020b) have shown in a split-root experiment that microorganisms from a suppressive soil induced systemic resistance in tomato plants (Hu et al, 2017) Cyst Leptosphaeria,Clonostachys,Purpureocillium,Penicillium,Pochonia,Fusarium,Exophiala,Mortierella,Microstroma,Typhula,Phoma,Oudemansiella,Saksenaea,Melanospora,Xylaria,Orbilia,Enterobacter,Acidovorax,Pseudomonas,Variovorax,Rhizobium,Serratia,Massilia,Dactylosporangium,Lentzea,Amycolatopsis,Mesorhizobium,Actinoplanes,Asteroleplasma,Nocardia,Bradyrhizobium,Actinocorallia,Micromonospora,Streptosporangium,Kribbella,Phyllobacterium,Devosia,Nonomuraea,Actinomadura,Aminobacter,Sphingomonas,Shinella,Chitinophaga,Niastella,Steroidobacter,Kineosporia,Luteolibacter,Lysobacter,Rhodanobacter,Echinococcus Heterodera glycines …”

“…Notably, most research has been done on a few species of the endoparasitic sedentary genera Meloidogyne, Heterodera, and Globodera. Investigations on other PPN will give the opportunity to generalize conclusions on the interactions of PPN within the phytobiome and to acknowledge species or genus specific differences in life strategies (Topalović et al, 2020b). Microorganisms contributing to the natural suppression of PPN in soils have been studied using culture-dependent and culture-independent methods.…”