No rest for resting spores: Can predators mitigate clubroot disease?

Abstract

The clubroot pathogen Plasmodiophora brassicae is a major and growing problem for the cultivation of Brassica crops. As conventional control disease management methods are ineffective or prohibited due to their ecological impact, and crop resistance is frequently broken, biological control of the pathogen has become a key focus for the development of sustainable agricultural systems. Here we provide a perspective review on the unexplored impact of soil microbiome predators, and their potential use as biocontrol agents, using clubroot disease as an example. We highlight several pathways by which microbiome predators can reduce clubroot in soils, including directly through predation and indirectly by inducing a clubroot-suppressive microbiome. We further discuss how some microbiome predators might, in contrast, benefit clubroot disease spread through mechanisms such as phoresy toward hosts. We highlight that gaps in knowledge need to be filled that hinder wider application of microbiome predators against P. brassicae alone, and in combination with known biocontrol agents.

Biocontrol of clubroot disease: how successful are endophytic fungi and bacteria?

“…Living organisms in the soil, the rhizobiome and microbiome predators such as other protists, nematodes and arthropods can all influence the survival and therefore establishment and efficacy of biocontrol microorganisms against clubroot through competition, antibiosis or predation. So far, hardly anything is known about this complex topic in regard to clubroot, yet a recent study showed nonspecific consumption of P. brassicae resting spores by other protists (Schwelm et al, 2023).…”

Microbiome predators in changing soils

“…Through predation, microbiome predators release the nutrients inside their prey (nitrogen, phosphorus, or silica) or enhance prey activity to mobilize these nutrients (Jiang et al, 2023; Puppe, 2020; Ranoarisoa et al, 2020), which then become available and increase plant growth (Figure 1; Thakur & Geisen, 2019). Microbiome predators might also promote pathogen‐suppressive microorganisms via changes in the community composition (Gao et al, 2019; Guo et al, 2022; Thakur & Geisen, 2019) and feed on plant pests and pathogens, thereby reducing plant diseases (Figure 1; Geisen et al, 2016; Schwelm et al, 2023). Additionally, microbiome predators play a role in carbon cycling, by enhancing litter decomposition (Figure 1).…”