Temporal dynamics of bacterial and fungal communities during the infection of Brassica rapa roots by the protist Plasmodiophora brassicae

Abstract

The temporal dynamics of rhizosphere and root microbiota composition was compared between healthy and infected Chinese cabbage plants by the pathogen Plasmodiophora brassicae . When inoculated with P . brassicae , disease was measured at five sampling dates from early root hair infection to late gall development. The first symptoms of clubroot disease appeared 14 days after inoculation (DAI) and increased drastically between 14 and 35 DAI. The structure of microbial communities associated to rhizosphere soil and root from healthy and inoculated plants was characterized through high-throughput DNA sequencing of bacterial (16S) and fungal (18S) molecular markers and compared at each sampling date. In healthy plants, Proteobacteria and Bacteroidetes bacterial phyla dominated the rhizosphere and root microbiota of Chinese cabbage. Rhizosphere bacterial communities contained higher abundances of Actinobacteria and Firmicutes compared to the roots. Moreover, a drastic shift of fungal communities of healthy plants occurred between the two last sampling dates, especially in plant roots, where most of Ascomycota fungi dominated until they were replaced by a fungus assigned to the Chytridiomycota phylum. Parasitic invasion by P . brassicae disrupted the rhizosphere and root-associated community assembly at a late step during the root secondary cortical infection stage of clubroot disease. At this stage, Flavisolibacter and Streptomyces in the rhizosphere, and Bacillus in the roots, were drastically less abundant upon parasite invasion. Rhizosphere of plants colonized by P . brassicae was significantly more invaded by the Chytridiomycota fungus, which could reflect a mutualistic relationship in this compartment between these two microorganisms.

Bacterial composition in brassica‐cultivated soils with low and high severity of clubroot

“…The obtained results were consistent with those verified by Lebreton et al. (2019) when studying the rhizospheric composition dynamics of healthy and P. brassicae ‐infected Chinese cabbage plants. The authors reported a greater abundance of Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes in the rhizosphere of healthy plants.…”

“…Protists of free living can affect the populations of microorganisms in the soil and modify the rhizospheric microbiome through predation (by Bacteria, Archaea, Fungi and Algae) (Flues, Bass, & Bonkowski, 2017; Geisen & Bonkowski, 2017; Geisen et al., 2018; Hunninghaus, Koller, & Kramer, 2017; Jousset, 2017). Also, infection of chinese cabbage plants by P. brassicae can affect the temporal dynamics of its rhizosphere and its root microbiota composition (Lebreton et al., 2019). Pathogen growth and subsequent plant infection may be reduced due to positive plant interactions and microbial rhizosphere communities, which may have beneficial effects on plant growth and health, including the suppression of disease (Huang et al., 2014).…”

Impact of a resistance gene against a fungal pathogen on the plant host residue microbiome: the case of theLeptosphaeria maculans-Brassica napuspathosystem

“…The effect of L. maculans on the microbiome of oilseed rape residues was characterised with two near-isogenic oilseed rape lines, Darmor and Darmor-Rlm11, which carries an efficient resistance gene against stem canker. Oilseed rape residues with and without L. maculans infection are difficult to obtain in controlled conditions, by contrast to other pathosystems, such as Z. tritici on wheat residues (Kerdraon et al, 2019b) or Plasmodiophora brassicae on B. napus (Lebreton et al, 2019). There is also, generally, a large difference between the microbial communities present on plants in field conditions and those obtained in greenhouses (Ritpitakphong et al, 2016).…”

“…The role of the microbiota in the plant's response to a disease or in the pathogenicity of a fungal pathogen is currently being studied in various pathosystems, but remains poorly understood. Changes in microbial communities induced by the presence of plant pathogens and temporal changes in assemblies during the course of an epidemic are increasingly being studied with high-throughput sequencing techniques (Cho and Blaser, 2012;Jakuschkin et al, 2016;Lebreton et al, 2019).…”

Metatranscriptomic dynamics after Verticillium dahliae infection and root damage in Olea europaea

“…So, Mgnify ID MGYS00001376 refers to the still unpublished study of the infection of pedunculate oak by Erysiphe alphitoides, the causal agent of oak powdery mildew. And Mgnify ID MGYS00002393 applies to the temporal dynamics of bacterial and fungal communities during the infection of Brassica rapa roots by the protist Plasmodiophora brassicae [10]. Some recent works [11] focus on the characterization of fungal metagenomics in animal species, especially those from pig and mouse microbiomes.…”