ena-STUDY-INRA (INRA Rennes)-24-05-2018-15:44:22:133-116
Temporal dynamics of bacterial and fungal communities during the infection of Brassica rapa roots by the protist Plasmodiophora brassicae
This study was conducted to assess the temporal dynamics of rhizosphere and root microbiota during the development of Plasmodiophora brassicae in root hairs of Chinese cabbage (Brassica rapa subsp. pekinensis). After inoculation (or not) with P. brassicae, disease was assessed at five sampling date during the vegetative stage of plant growth. The first symptom 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 samples was assessed at each sampling date through sequencing of bacterial (16S) and fungal (18S) molecular markers. Proteobacteria and Bacteroidetes bacterial phyla dominate the Chinese cabbage rhizosphere and root microbiota. Rhizosphere bacterial communities also contained Actinobacteria and Firmicutes to a higher extend than in the roots. Moreover, a dramatic shift of fungal communities of non-inoculated plants occurred between the two last sampling dates, especially in plant roots but also in their rhizosphere. Most of Ascomycota fungi dominant until then were replaced by a fungus assigned to the Chytriomycota phylum. Parasitic invasion by P. brassicae disrupted the rhizosphere and root-associated community assembly during the vegetative stage of plant growth. These effects occurred late during the secondary cortical infection stage of clubroot disease in plant roots. 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 Chytriomycota fungus, which could reflect a mutualistic relationship in this compartment between these two microorganisms.
This study was conducted to assess the temporal dynamics of rhizosphere and root microbiota during the development of Plasmodiophora brassicae in root hairs of Chinese cabbage (Brassica rapa subsp. pekinensis). After inoculation (or not) with P. brassicae, disease was assessed at five sampling date during the vegetative stage of plant growth. The first symptom 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 samples was assessed at each sampling date through sequencing of bacterial (16S) and fungal (18S) molecular markers. Proteobacteria and Bacteroidetes bacterial phyla dominate the Chinese cabbage rhizosphere and root microbiota. Rhizosphere bacterial communities also contained Actinobacteria and Firmicutes to a higher extend than in the roots. Moreover, a dramatic shift of fungal communities of non-inoculated plants occurred between the two last sampling dates, especially in plant roots but also in their rhizosphere. Most of Ascomycota fungi dominant until then were replaced by a fungus assigned to the Chytriomycota phylum. Parasitic invasion by P. brassicae disrupted the rhizosphere and root-associated community assembly during the vegetative stage of plant growth. These effects occurred late during the secondary cortical infection stage of clubroot disease in plant roots. 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 Chytriomycota fungus, which could reflect a mutualistic relationship in this compartment between these two microorganisms.