Biology subjects

Berendsen, R.

Publications and source records attributed to Berendsen, R..

4 recordsLinked to original sources

bioRxiv2025

Patchy distribution of potato cyst nematodes within single arable fields reveals local disease suppressiveness mediated by disparate microbialcommunities

Disease suppressiveness is a complex phenomenon that is assumed to be the resultant of actions of local microbial antagonists in soil environments. Exploitation of disease suppressiveness as a tool to manage pathogens is hindered by our poor understanding of this phenomenon. Here we investigated soil microbiome-based suppression of potato cyst nematodes (PCN), and, to this end, four apparently homogeneous potato fields with an unexplained non-homogeneous PCN distribution were selected. We hypothesized that this patchy PCN distribution resulted from local variation in disease suppressiveness. Under controlled greenhouse conditions, we confirmed the suppressiveness of these soils vis-a-vis PCN and soils were gamma-irradiated to corroborate the biotic origin of this suppression. Subsequent DNA-based analysis of the microbial community in the potato rhizosphere revealed suppressiveness-related contrasts in community composition between suppressive and conducive patches. Elevated abundances of fungal (e.g., Metacordyceps chlamydosporia) and bacterial (e.g., Pseudomonas fluorescens) nematode antagonists were positively correlated with PCN suppressive patches. Distinct sets of antagonists were found to be associated with PCN suppression despite of the geographical closeness of the locations under investigation. Our findings confirm the biotic origin of local PCN suppressiveness and reveal that it should be regarded as a superficially similar resultant of a biologically diverse phenomenon.

ecology↗

bioRxiv2024

Selective enrichment of specific bacterial taxa in downy mildew-affected spinach: Comparative analysis in laboratory and field conditions

Plants host diverse microbial communities that can be influenced by their hosts to mitigate biotic stress. Previous research demonstrated that distinct laboratory cultures of Hyaloperonospora arabidopsidis (Hpa) on Arabidopsis thaliana, consistently harbor nearly identical bacteria. In this study, we analyzed the bacterial phyllosphere communities of laboratory-grown spinach plants infected by the downy mildew pathogen Peronospora effusa (Pe). Using 16S amplicon sequencing, we identified 14 Amplicon Sequence Variants (ASVs), with diverse taxonomies, that were enriched in at least 3 out of 5 investigated Pe cultures. This small set of 14 ASVs occupied on average 6.9% of the total bacterial communities in healthy spinach plants, and 43.1% in Pe-inoculated plants. A specific Rhodococcus and a Paenarthrobacter ASV were particularly prevalent and abundant. To validate these findings outside of the laboratory, we planted a susceptible variety of spinach in 4 agricultural fields and sampled leaves from Pe-infected plants in 2 fields where this pathogen naturally occurred. Comparative microbiome analysis of diseased and healthy plants revealed significant enrichment of 16 and 31 ASVs in these 2 fields, respectively. Among these, the Paenarthrobacter ASV was enriched in one field and the Rhodococcus ASV in the other field, suggesting that disease-associated microbiota that are abundantly detected in Pe laboratory cultures are also associated with Pe-infected field plants. Additionally, we observed an overlap of ASVs that were associated with both Pe and Hpa, indicating that similar bacteria are linked to downy mildew disease across different hosts.

microbiology↗

bioRxiv2023

A tripartite bacterial-fungal-plant symbiosis in the mycorrhiza-shaped microbiome drives plant growth and mycorrhization

Plant microbiomes play crucial roles in nutrient cycling and plant growth, and are shaped by a complex interplay between plants, microbes, and the environment. The role of bacteria as mediators of the 400-million-year-old partnership between the majority of land plants and, arbuscular mycorrhizal (AM) fungi is still poorly understood. Here we test whether AM hyphae-associated bacteria influence the success of the AM symbiosis. Using partitioned microcosms containing field soil, we discovered that AM hyphae and roots selectively assemble their own microbiome from the surrounding soil. In two independent experiments, we identified several bacterial genera, including Devosia, that are consistently enriched on AM hyphae. Subsequently, we isolated 144 pure bacterial isolates from a mycorrhiza-rich sample of extraradical hyphae and isolated Devosia sp. ZB163 as root and hyphal colonizer. We show that this AM-associated bacterium synergistically acts with mycorrhiza on the plant root to strongly promote plant growth, nitrogen uptake, and mycorrhization. Our results highlight that AM fungi do not function in isolation and that the plant-mycorrhiza symbiont can recruit beneficial bacteria that support the symbiosis.

microbiology↗

bioRxiv2023

Congruent downy mildew-associated microbiomes reduce plant disease and function as transferable resistobiomes

Root-associated microbiota can protect plants against severe disease outbreaks. In the model-plant Arabidopsis thaliana, leaf infection with the obligate downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa) results in a shift in the root exudation profile, therewith promoting the growth of a selective root microbiome that induces a systemic resistance against Hpa in the above-ground plant parts. Here we show that, additionally, a conserved subcommunity of the recruited soil microbiota becomes part of a pathogen-associated microbiome in the phyllosphere that is vertically transmitted with the spores of the pathogen to consecutively infected host plants. This subcommunity of Hpa-associated microbiota (HAM) limits pathogen infection and is therefore coined a "resistobiome". The HAM resistobiome consists of a small number of bacterial species and was first found in our routinely maintained laboratory cultures of independent Hpa strains. When co-inoculated with Hpa spores, the HAM rapidly dominates the phyllosphere of infected plants, negatively impacting Hpa spore formation. Remarkably, isogenic bacterial isolates of the abundantly-present HAM species were also found in strictly separated Hpa cultures across Europe, and even in early published genomes of this obligate biotroph. Our results highlight that pathogen-infected plants can recruit protective microbiota via their roots to the shoots where they become part of a pathogen-associated resistobiome that helps the plant to fight pathogen infection. Understanding the mechanisms by which pathogen-associated resistobiomes are formed will enable the development of microbiome-assisted crop varieties that rely less on chemical crop protection.

microbiology↗