Biology subjects

Habring, A.

Publications and source records attributed to Habring, A..

5 recordsLinked to original sources

bioRxiv2026

Natural selection acting on the genetics of host response to commensal bacteria

BackgroundMicrobiota members collectively contribute to individual performance in humans, animals, and plants. This led to the quest for probiotics to improve host health and reproductive performance. Although the efficacy of probiotics is known to be strongly affected by environmental factors, microbe-microbe interactions, and microbial strain identity, the effects of host genotype and the underlying genetic architecture have been overlooked. In addition, the evolutionary causes of such genetic variation are typically not addressed. In this study, we aimed to describe the genetic architecture of the adaptation of the host plant Arabidopsis thaliana to commensal bacterial members of its native microbiota by identifying candidate genes associated with fitness proxies and presenting signatures of natural selection. ResultsA Genome-Wide Association study conducted under field conditions revealed extensive variation within a new mapping population of 162 genotypes of A. thaliana scored for total seed production and its two underlying components, namely fruit number and mean seed number per fruit, in response to 13 commensal strains. In agreement with the strong host genotype x commensal strain identity interactions observed for each reproductive trait, the polygenic genetic architecture was highly flexible among the 13 commensal strains. Candidate genes exhibited a significant enrichment in signatures of both local adaptation and balancing selection. In line with the phenotyped reproductive traits, we identified seven candidate genes with functions specifically and strongly linked to seed germination and fertility. ConclusionsOur findings reveal the importance of genotype-by-genotype interactions when measuring fitness proxies on a wild plant species inoculated with key members of its native microbiota. In addition, this study improves our understanding of the genetic signatures of natural selection acting on native host-microbiota adaptive interactions.

evolutionary biology↗

bioRxiv2024

The 1001G+ project: A curated collection of Arabidopsis thaliana long-read genome assemblies to advance plant research

Arabidopsis thaliana was the first plant for which a high-quality genome sequence became available. The publication of the first reference genome sequence almost 25 years ago was already accompanied by genome-wide data on sequence polymorphisms in another accession, or naturally occurring strain. Since then, inventories of genome-wide diversity have been generated at increasingly precise levels. High-density genotype data for A. thaliana, including those from the 1001 Genomes Project, were key to demonstrating the enormous power of GWAS in inbred populations of wild plants, and the comparison of intraspecific polymorphism with interspecific divergence has illuminated many aspects of plant genome evolution. Over the past decade, an increasing number of nearly complete genome sequences have been published for many more accessions. Here, we highlight the diversity of a curated collection of previously published and so far unpublished genome sequences assembled using different types of long reads, including PacBio Continuous Long Reads (CLR), PacBio High Fidelity (HiFi) reads, and Oxford Nanopore Technologies (ONT) reads. This 1001 Genomes Plus (1001G+) resource is being made available at http://1001genomes.org. We invite colleagues with yet unpublished genome assemblies from A. thaliana accessions to contribute to this effort.

genomics↗

bioRxiv2023

Structural variation and DNA methylation shape the centromere-proximal meiotic crossover landscape in Arabidopsis

BackgroundCentromeres load kinetochore complexes onto chromosomes, which mediate spindle attachment and allow segregation during cell division. Although centromeres perform a conserved cellular function, their underlying DNA sequences are highly divergent within and between species. Despite variability in DNA sequence, centromeres are also universally suppressed for meiotic crossover recombination, across eukaryotes. However, the genetic and epigenetic factors responsible for suppression of centromeric crossovers remain to be completely defined. ResultsTo explore the centromere-proximal recombination landscape, we mapped 14,397 crossovers against fully assembled Arabidopsis thaliana genomes. A. thaliana centromeres comprise megabase-scale satellite repeat arrays that load nucleosomes containing the CENH3 histone variant. Each chromosome possesses a structurally polymorphic 3-4 megabase region where crossovers were absent, that includes the satellite arrays, flanked by 1-2 megabase low-recombination zones. The recombination-suppressed regions are enriched for Gypsy/Ty3 retrotransposons, and additionally contain expressed genes with high genetic diversity that initiate meiotic recombination, yet do not crossover. We mapped crossovers at high-resolution in proximity to CEN3, which resolved punctate centromere-proximal hotspots that overlapped gene islands embedded in heterochromatin. Centromeres are densely DNA methylated and the recombination landscape was remodelled in DNA methylation mutants. We observed that the centromeric low-recombining zones decreased and increased crossovers in CG (met1) and non-CG (cmt3) mutants, respectively, whereas the core non recombining zones remained suppressed. ConclusionOur work relates the genetic and epigenetic organisation of the A. thaliana centromeres and flanking pericentromeric heterochromatin to the zones of crossover suppression that surround the CENH3-occupied satellite repeat arrays.

genomics↗

bioRxiv2019

Oligomerization of the NLR immune receptor RPP7 triggered by the atypical resistance protein RPW8/HR as a ligand

In certain plant hybrids, autoimmunity is triggered by immune components that interact in the absence of a pathogen trigger. Often, NLR immune receptors are involved, with a particularly interesting case in Arabidopsis thaliana involving variants of the NLR RPP7 as well as variants of RPW8/HR proteins, which are homologs of animal MLKL and fungal HELL domain proteins. We demonstrate that HR4Fei-0 but not the closely related HR4Col-0 protein directly disrupts intramolecular association of RPP7bLerik1-3, which in turn initiates P-loop dependent NLR signaling. In agreement, RPP7bLerik1-3 forms a higher-order complex only in the presence of HR4Fei-0 but not HR4Col-0. In addition, we find that HR4Fei-0 on its own can form detergent-resistant oligomers suggestive of amyloid-like aggregates, which in turn can directly kill cells in an RPP7bLerik1-3-independent manner. Our work provides in vivo biochemical evidence for a plant resistosome complex and the mechanisms by which RPW8/HR proteins trigger cell death.

plant biology↗

bioRxiv2019

RPW8/HR Repeats Predict NLR-dependent Hybrid Performance

Hybrid offspring can look very different from their parents, including having greatly increased or decreased fitness. In many plant species, conflicts between divergent elements of the immune system can cause hybrids to express autoimmunity, a generally deleterious syndrome known as hybrid necrosis. We are investigating multiple hybrid necrosis cases in Arabidopsis thaliana that are caused by allele-specific interactions between different variants at two unlinked resistance (R) gene clusters. One is the RESISTANCE TO PERONOSPORA PARASITICA 7 (RPP7) cluster, which encodes an intracellular nucleotide binding site-leucine rich repeat (NLR) immune receptors that confer strain-specific resistance to oomycetes. The other is the RESISTANCE TO POWDERY MILDEW 8 (RPW8)/HOMOLOG OF RPW8 (HR) locus, which encodes atypical resistance proteins that can confer broad-spectrum resistance to filamentous pathogens. There is extensive structural variation in the RPW8/HR cluster, both at the level of gene copy number and at the level of C-terminal protein repeats of unknown function. We demonstrate that the number of RPW8/HR repeats correlate, albeit in a complex manner, with the severity of hybrid necrosis when these alleles are combined with specific RPP7 variants. This observation suggests that gross structural differences, rather than individual amino acid polymorphisms, guide the genetic interaction between RPW8/HR and RPP7 alleles. We discuss these findings in light of the similarity of RPW8/HR proteins with pore-forming toxins, MLKL and HET-S, from mammals and fungi.

genetics↗