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.