Soil microbiota influences clubroot disease by modulatingPlasmodiophora brassicaeandBrassica napustranscriptomes

Abstract

The contribution of surrounding plant microbiota to disease development has led to the 'pathobiome' concept, which represents the interaction between the pathogen, the host plant and the associated biotic microbial community, resulting or not in plant disease. The aim herein is to understand how the soil microbial environment may influence the functions of a pathogen and its pathogenesis, and the molecular response of the plant to the infection, with a dual-RNAseq transcriptomics approach. We address this question using Brassica napus and Plasmodiophora brassicae, the pathogen responsible for clubroot. A time-course experiment was conducted to study interactions between P. brassicae, two B. napus genotypes and three soils harbouring high, medium or low microbiota diversities and levels of richness. The soil microbial diversity levels had an impact on disease development (symptom levels and pathogen quantity). The P. brassicae and B. napus transcriptional patterns were modulated by these microbial diversities, these modulations being dependent on the host genotype plant and the kinetic time. The functional analysis of gene expressions allowed the identification of pathogen and plant host functions potentially involved in the change of plant disease level, such as pathogenicity-related genes (NUDIX effector) in P. brassicae and plant defence-related genes (glucosinolate metabolism) in B. napus.

Molecular Pathotyping of Plasmodiophora brassicae—Genomes, Marker Genes, and Obstacles

“…To identify more effector candidates, it is crucial that in transcriptomic clubroot investigations also the pathogen gene expression is analyzed. Certainly more effector candidates will come to light as seen in a recent study which identified a NUDIX-gene effector candidate in the eH isolate [75].…”

“…For P. brassicae, effector candidates were mainly identified by analyzing RNA-sequence data of infected hosts [18,21,22,33,34,75]. Based on the transcription pattern in different P. brassicae life stages of genes predicted to encode cysteine-rich small secreted proteins.…”

Nitrogen Supply and Host-Plant Genotype Modulate the Transcriptomic Profile of Plasmodiophora brassicae

“…First, clubroot symptoms were evaluated by a disease index calculated with the scale previously described (Manzanares-Dauleux et al, 2000). Secondly, 1 µl of DNA extracted from root samples (see next paragraph) was used for quantitative PCR on the 18S gene to quantify the P. brassicae amount as previously described (Daval et al, 2020).…”

“…At this stage, P. brassicae forms galls in root because of hypertrophy and hyperplasia of infected roots by the modification of hormone levels (Siemens et al, 2006), leading to the obstruction of nutrient and water transport and then a reduction of plant growth. During both primary and secondary phases, it has been suggested that P. brassicae could secrete effectors, but the validation of their real roles in infection is still in progress (Kombrink and Thomma, 2013;Schwelm et al, 2015b;Rolfe et al, 2016;Zhang et al, 2016;Perez-Lopez et al, 2018;Daval et al, 2019Daval et al, , 2020, except for a predicted secreted methyltransferase interfering in the plant salicylic acid-induced defense (Ludwig-Muller et al, 2015).…”

Control of Streptomyces alfalfae XY25T Over Clubroot Disease and Its Effect on Rhizosphere Microbial Community in Chinese Cabbage Field Trials

“…It is a place where pathogens attack plants and establish parasitic relationships (Kumar et al, 2020). Like other habitats, the rhizosphere contains a large number of interacting microbial populations, and it plays an important role in maintaining plant health (Wei et al, 2019;Daval et al, 2020). Rhizosphere microorganisms prevent or resist the invasion of soil-borne diseases through antagonism, nutrient competition, parasitism, and group sensing (Mendes et al, 2013), and the imbalance of microbial community in rhizosphere soil is an important cause of soil-borne diseases.…”