Biomedical subjects

Detlef Weigel

Publications and source records attributed to Detlef Weigel.

5 recordsLinked to original sources

PubMed2026

Eastern origin and three-millennia persistence of a founding grapevine lineage in Iberian viticulture.

Viticulture became central to most Mediterranean civilizations a few millennia after the grapevine (Vitis vinifera L.) was domesticated in the South Caucasus/Near East. To elucidate the origins of the grapevines that enabled this westward spread over the past 3,000 years, we analyzed 28 grapevine seeds from seven archaeological sites in the Iberian Peninsula and Sardinia. Ancient DNA recovered from the oldest seeds with domesticated-like morphology (from ∼1,000 BCE), found in southwestern Spain, revealed nuclear and chloroplast genome signatures of Eastern Mediterranean cultivars. Seeds from the same and later Iron Age Iberian sites, however, showed genomic signatures suggesting hybridization between local wild grapevines and eastern-origin cultivars. The genetic makeup of Sardinian and northeastern Spanish seeds supports that local diversification giving rise to the Central European and Iberian wine genetic lineages had already occurred in the early Iron Age. In Iberia, Roman-period seeds were first-degree related to both the earliest eastern-introduced domesticates and a Medieval seed whose genetic makeup matches the extant Iberian variety "Pasa Valenciana." Another Medieval seed was inferred as an offspring of the extant "Heben," indicating that this major founder of Iberian germplasm has been continuously propagated for over 1,100 years. Our results confirm previous evolutionary models indicating that Western Mediterranean viticulture began with introductions of eastern domesticated grapevines, followed by early hybridization with local Iberian wild grapevines that may have facilitated viticulture adaptation to the new environment. The aDNA unveils that these introductions gave rise to extant cultivars through only a few sexual generations and long-term reliance on clonal propagation.

Iberian Peninsula↗

PubMed2025

Divergent and stabilizing selection shape the phenotypic space of Arabidopsis thaliana.

Why do we observe some plant phenotypes but not others? The multivariate phenotypic space occupied by individuals or species often reveals both limits and phenotypes strikingly deviating from main syndromes. These observations are usually thought to indicate, respectively, inviable trait combinations and unique phenotypes adapted to specific environments. However, the evolutionary drivers underlying trait covariations often remain unclear. Here, we characterized the phenotypic space of Arabidopsis thaliana by comparing 713 wild accessions collected across the globe with 2,544 artificially-created recombinant individuals. This, combined with the detection of adaptive processes operating within species, allowed us to elucidate the roles of natural selection as a driver of phenotypic (co)variations within A. thaliana. We found that the phenotypic space of this species is constrained and driven by varying levels of divergent and stabilizing selection across different traits. Moreover, at the margins of the European geographic range, strong directional selection favored outlier phenotypes characterized by very late flowering and variation in a WRKY transcription factor gene. Genome analyses revealed that these extreme phenotypes may be explained by hybridization between ancestral and modern lineages of A. thaliana. Our findings demonstrate how interplays between population history and natural selection shape phenotypic diversity in a plant species.

Arabidopsis↗

PubMed2025

iNOME-seq: in vivo simultaneous genome-wide mapping of chromatin accessibility, nucleosome positioning, DNA-binding protein sites, and DNA methylation in Arabidopsis.

We present iNOMe-seq, a novel method for in vivo simultaneous profiling of chromatin accessibility, nucleosome occupancy, DNA-binding protein sites, and DNA methylation in living tissues. iNOMe-seq utilizes an m5C methyltransferase to mark accessible cytosines in a GpC context, bypassing nucleosome-restricted regions. Using Arabidopsis thaliana, we demonstrate that iNOMe-seq improves chromatin accessibility quantification compared to existing methods. Furthermore, it allows for the spatial and temporal analysis of chromatin dynamics, transcription factor binding, and DNA methylation, offering insight into the role of epigenetic components in transcriptional regulation across tissues and genetic variations in natural populations.

Arabidopsis↗

PubMed2025

A major trade-off between growth and defense in Arabidopsis thaliana can vanish in field conditions.

When wild plants defend themselves from pathogens, this often comes with a trade-off: the same genes that protect a plant from disease can also reduce its growth and fecundity in the absence of pathogens. One protein implicated in a major growth-defense trade-off is ACCELERATED CELL DEATH 6 (ACD6), an ion channel that modulates salicylic acid (SA) synthesis to potentiate a wide range of defenses. Wild Arabidopsis thaliana populations maintain significant functional variation at the ACD6 locus, with some alleles making the protein hyperactive. In the greenhouse, plants with hyperactive ACD6 alleles are resistant to diverse pathogens, yet they are of smaller stature, their leaves senesce earlier, and they set fewer seeds compared to plants with the standard allele. We hypothesized that ACD6 hyperactivity would not only affect the growth of microbial pathogens but also more generally change leaf microbiome assembly. To test this in an ecologically meaningful context, we compared plants with hyperactive, standard, and defective ACD6 alleles in the same field-collected soil, both outdoors and in naturally lit and climate-controlled indoor conditions, taking advantage of near-isogenic lines as well as a natural accession and a CRISPR-edited derivative. We surveyed visual phenotypes, gene expression, hormone levels, seed production, and the microbiome in each environment. The genetic precision of CRISPR-edited plants allowed us to conclude that ACD6 genotype had no effect on mature field plants in our setting, despite reproducibly dramatic effects on greenhouse plants. We conclude that additional abiotic and/or microbial signals present outdoors-but not in the greenhouse-greatly modulate ACD6 activity. This raises the possibility that the fitness costs of other commonly studied immune system genes may be grossly misjudged without field studies.

Arabidopsis↗

PubMed2025

Species-wide gene editing of a flowering regulator reveals hidden phenotypic variation.

Genes do not act in isolation, and the effects of a specific variant at one locus can often be greatly modified by polymorphic variants at other loci. A good example is FLOWERING LOCUS C (FLC), which has been inferred to explain much of the flowering time variation in Arabidopsis thaliana. We use a set of 62 flc species-wide mutants to document pleiotropic, genotype-dependent effects for FLC on flowering as well as several other traits. Time to flowering was greatly reduced in all mutants, with the remaining variation explained mainly by allelic variation at the FLC target FT. Analysis of FT sequence variation suggested that extremely early combinations of FLC and FT alleles should exist in the wild, which we confirmed by targeted collections. Our study provides a proof of concept on how pan-genetic analysis of hub genes can reveal the true extent of genetic networks in a species.

Gene Editing↗