Biology subjects

Pieterse, C. M.

Publications and source records attributed to Pieterse, C. M..

5 recordsLinked to original sources

bioRxiv2026

Root gene regulatory network analysis reveals roles for defense hormones and secondary metabolites in establishment of disease-suppressive soil

Plants recruit beneficial microbiota in their rhizosphere to alleviate stresses. In Arabidopsis thaliana, foliar infection by Hyaloperonospora arabidopsidis (Hpa) has been shown to establish a disease-suppressive microbiome that promotes protection against Hpa infection of the subsequent plant generation grown in this conditioned soil - a phenomenon known as soil-borne legacy (SBL). The root responses involved in SBL establishment have remained largely unclear. In this study, time-series RNA-seq of roots from Hpa-infected plants grown in natural soil was conducted over seven days post-inoculation. A gene regulatory network of the responding roots was constructed. The role of predicted key components was verified in follow-up assays. Root transcriptional reprogramming started within one day after foliar infection. Genes associated with salicylic acid (SA)-mediated defense were upregulated, while those linked to secondary metabolism and jasmonic acid (JA) responsiveness were downregulated. SA accumulation increased at 1 dpi, and JA decreased by 3 dpi. Transcriptional regulation occurred primarily in the tips of the roots. Mutant analyses confirmed that SA, JA, indole glucosinolates, camalexin, and flavonoids contribute to SBL establishment. Our findings reveal rapid systemic transcriptional reprogramming in roots upon foliar pathogen attack, uncovering novel roles of hormone signaling and secondary metabolism in shaping a disease-suppressive soil beyond their known defense functions.

plant biology↗

bioRxiv2026

Beyond the annotated: protein foundation models enable robust prediction of microbial root competence

BackgroundRoot competence, the ability of soil bacteria to establish and grow on plant roots, is a key ecological trait influencing plant nutrition, growth, and health. However, identifying genomic determinants of root competence across bacteria remains challenging, in part because model generalisability depends strongly on how genomes are represented. Traditional approaches based on curated annotations are incomplete and biased toward well-characterised organisms and functions, limiting generalisation. Sequence-similarity clustering improves coverage but yields high-dimensional features relative to dataset size, hindering training. Foundation models offer an alternative by learning com-pact representations without relying on prior annotation. ResultsHere, we compared pretrained genome representations from protein and DNA foundation models (ESM-2, Bacformer, DNABERT-S) with annotation- and clustering-based features (KEGG orthology, OrthoFinder protein families) for predicting root competence using synthetic microbial community data from Arabidop-sis thaliana and assessed generalisability across bacteria. When training and test sets contained taxonomically related bacteria, most approaches performed similarly. However, when test bacteria belonged to phyla entirely absent from training, reflecting high evolutionary separation across all levels of bacterial classification, only pretrained protein representations retained predictive performance. Bacformer-derived representations, which incorporate genomic context, supported the strongest generalisation, suggesting that conserved genomic organisation contributes to predicting root competence. Feature attribution quantifying protein contributions to model decisions linked root competence to TonB/SusD-dependent receptors, small-molecule transporters, and unannotated proteins with conserved regulatory motifs and homology to carbon starvation-response loci. ConclusionsProtein foundation models support generalisation across evolutionarily distant bacteria and identify genomic determinants of root competence, including unannotated proteins.

genomics↗

bioRxiv2024

High-resolution quantification of the rhizosphere effect along a soil-to-root gradient shows selection-driven convergence of rhizosphere microbiomes

Plants secrete a complex array of organic compounds, constituting about a third of their photosynthetic products, into the surrounding soil. As a result, concentration gradients are established from the roots into the bulk soil, known as the rhizosphere. Soil microbes benefit from these root exudates for their survival and propagation, and consequently, the composition of the rhizosphere microbial community follows the gradient of available compounds, a phenomenon oftentimes referred to as the rhizosphere effect. However, the fine-grained changes in the microbial community along this soil-root gradient have not been well described. Yet such insights would enable us to underpin the ecological rules underlying root microbial community assembly. Therefore, here we harvested the roots of individual Arabidopsis thaliana plants grown in three different natural soils at high-resolution, such that we could interrogate community assembly and predict microbial growth rate across consecutive, fine-grained, rhizosphere compartments. We found that the strength of the rhizosphere effect depends on root proximity and that microbial communities closer to the roots harbour related microbes. Closer to the roots, microbial community assembly became less random and more driven by selection-based processes. Intriguingly, we observed priority effects, where related microbes that arrive first are more likely to establish, and that microbes might use different ecological growth strategies to colonise the rhizosphere. All effects appeared to be independent from starting conditions as microbial community composition converged on the root despite different soil microbial seed banks. Together, our results provide a high-resolution view of the microbiome changes across the soil-root gradient.

plant biology↗

bioRxiv2022

Cell-type specific transcriptomics reveals roles for root hairs and endodermal barriers in interaction with beneficial rhizobacterium

Growth-promoting bacteria can boost crop productivity in a sustainable way. Pseudomonas simiae WCS417 is a well-studied bacterium that promotes growth of many plant species. Upon colonization, WCS417 affects root system architecture resulting in an expanded root system. Both immunity and root system architecture, are controlled by root-cell-type specific biological mechanisms, but it is unknown how WCS417 affects these mechanisms. Therefore, here, we transcriptionally profiled five Arabidopsis thaliana root cell types following WCS417 colonization. The cortex and endodermis displayed the most differentially expressed genes, even though they were not in direct contact with this epiphytic bacterium. Many of these genes are associated with reduced cell wall biogenesis, possibly facilitating the root architectural changes observed in WCS417-colonized roots. Comparison of the transcriptome profiles in the two epidermal cell types that were in direct contact with WCS417 - trichoblasts that form root hairs and atrichoblasts that dont - imply functional specialization. Whereas basal expression levels of nutrient uptake-related genes and defense-related genes are highest in trichoblasts and atrichoblasts, respectively, upon exposure to WCS417 these roles revert. This suggests that root hairs participate in the activation of root immunity, further supported by attenuation of immunity in a root hairless mutant. Furthermore, we observed elevated expression of suberin biosynthesis genes and increased deposition of suberin in the endodermis in WCS417-colonized roots. Using an endodermal barrier mutant we show the importance of endodermal barrier integrity for optimal plant-beneficial bacterium association. Altogether, we highlight the strength of cell-type-specific transcriptional profiling to uncover "masked" biological mechanisms underlying successful plant-microbe associations.

plant biology↗

bioRxiv2019

Abscisic acid is essential for rewiring of jasmonic acid-dependent defenses during herbivory

Jasmonic acid (JA) is an important plant hormone in the regulation of defenses against chewing herbivores and necrotrophic pathogens. In Arabidopsis thaliana, the JA response pathway consists of two antagonistic branches that are regulated by MYC- and ERF-type transcription factors, respectively. The role of abscisic acid (ABA) and ethylene (ET) in the molecular regulation of the MYC/ERF antagonism during plant-insect interactions is still unclear. Here, we show that production of ABA induced in response to leaf-chewing Pieris rapae caterpillars is required for both the activation of the MYC-branch and the suppression of the ERF-branch during herbivory. Exogenous application of ABA suppressed ectopic ERF-mediated PDF1.2 expression in 35S::ORA59 plants. Moreover, the GCC-box promoter motif, which is required for JA/ET-induced activation of the ERF-branch genes ORA59 and PDF1.2, was targeted by ABA. Application of gaseous ET counteracted activation of the MYC-branch and repression of the ERF-branch by P. rapae, but infection with the ET-inducing necrotrophic pathogen Botrytis cinerea did not. Accordingly, P. rapae performed equally well on B. cinerea-infected and control plants, whereas activation of the MYC-branch resulted in reduced caterpillar performance. Together, these data indicate that upon feeding by P. rapae, ABA is essential for activating the MYC-branch and suppressing the ERF-branch of the JA pathway, which maximizes defense against caterpillars.

plant biology↗