Biology subjects

Baumgart, L. A.

Publications and source records attributed to Baumgart, L. A..

4 recordsLinked to original sources

bioRxiv2026

Positional grammar of transcription factor binding partitions developmental and stress-response regulation in plants

Understanding how transcription factor binding site (TFBS) position influences gene regulation remains a fundamental challenge in plants. Here, we integrate conserved multiDAP TFBS maps for 244 transcription factors (TFs) with single-nucleus chromatin accessibility, cell type-resolved gene expression, and hormone-response datasets across Brassicaceae species to determine how TFBS position relates to regulatory function. Although conserved TFBSs are enriched near transcription start sites (TSSs), TSS-proximal accessibility poorly predicts cell type-specific expression. Instead, cell type-specific expression correlates best with conserved TFBSs embedded in cell type-restricted chromatin, with TF family-specific distributions across distal promoters and introns. In contrast, TSS-proximal TFBSs in broadly accessible chromatin are associated with rapid transcriptional responses to abiotic and biotic stress hormones. Coding sequence TFBSs mark a distinct regulatory context in which the same DNA sequence encodes both amino acid sequence and TF motifs, including evidence that CDS-localized ABR1 binding may contribute to repression during hormone response. Finally, distal upstream regions contain conserved multi-family TF clusters with enhancer-like features overlapping rare cell type-specific accessible chromatin and enriched near genes controlling embryonic, meristematic, and hormone-dependent developmental patterning. Together, these results support a positional grammar in which TFBS position and chromatin context jointly partition developmental, stress-responsive, and repressive regulatory output in plants.

genomics↗

bioRxiv2025

Genome-wide exploration of the transcriptional regulatory landscape in the early-diverging fungus R. microsporus reveals pervasive DNA methyl adenine regulatory network

Genetic regulation mechanisms rely on complex transcriptional networks that are often difficult to decipher. The study of transcription factor (TF) binding sites and their targets has traditionally faced scalability challenges, hindering comprehensive cistrome analyses. However, the development of the DNA affinity purification and sequencing (DAP-seq) technique has allowed unprecedented large-scale studies at genome-wide level of TF binding with high reproducibility. In this study, we apply this technique to the human opportunistic pathogen R. microsporus, a mucoralean fungus belonging to the understudied group of early-diverging fungi (EDF). We characterize genome-wide binding sites of 58 TFs encoded by genes regulated through adenine methylation and representing major TF families, representing the most extensive DAP-seq study in filamentous fungi. This analysis reveals their binding profiles and recognized sequences, expanding and diversifying the catalog of known fungal motifs. By integrating this data with DNA 6-methyladenine profiling, we uncover the extensive direct and indirect impact of this epigenetic modification on the regulation of gene expression. Furthermore, the generated data facilitates the identification and functional characterization of TFs involved in biologically relevant processes, such as zinc metabolism and light response, serving as a proof of concept for the utility of the DAP-seq data. These findings not only enhance our understanding of regulatory mechanisms in R. microsporus but also provide broader insights into gene regulation across the fungal kingdom.

genetics↗

bioRxiv2024

An atlas of conserved transcription factor binding sites reveals the cell type-resolved gene regulatory landscape of flowering plants

Transcription factors (TFs) are proteins that bind DNA to control where and when genes are expressed. In plants, dozens of TF families interact with distinct sets of binding sites (TFBSs) that reflect each TFs role in organismal function and species-specific adaptations. However, defining these roles and understanding broader patterns of regulatory evolution remains challenging, as predicted TFBSs may lack a clear impact on transcription, and experimentally-derived TF binding maps to date are modest in scale or restricted to model organisms. Here, we present a scalable TFBS assay that we leveraged to create an atlas of nearly 3,000 genome-wide binding site maps for 360 TFs in 10 species spanning 150 million years of flowering plant evolution. We find that TF orthologs from distant species retain nearly identical binding preferences, suggesting that regulatory evolution primarily arises from gain and loss of TFBSs. Within lineages however, conserved TFBSs are over-represented and found in regions harboring signatures of functional regulatory elements. Moreover, genes with conserved TFBSs showed a striking enrichment for cell type-specific expression in single-nuclei RNA atlases, providing a robust marker of each TFs activity and developmental role. Finally, we compare distant lineages, illustrating how ancient regulatory modules were recruited and rewired to enable adaptations underlying the evolutionary success of grasses.

genomics↗

bioRxiv2024

Shoring up the base: the development and regulation of cortical sclerenchyma in grass nodal roots

Plants depend on the combined action of a shoot-root-soil system to maintain their anchorage to the soil. Mechanical failure of any component of this system results in lodging, a permanent and irreversible inability to maintain vertical orientation. Models of anchorage in grass crops identify the compressive strength of roots near the soil surface as key determinant of resistance to lodging. Indeed, studies of disparate grasses report a ring of thickened, sclerenchyma cells surrounding the root cortex, present only at the base of nodal roots. Here, in the investigation of the development and regulation of this agronomically important trait, we show that development of these cells is uncoupled from the maturation of other secondary cell wall-fortified cells, and that cortical sclerenchyma wall thickening is stimulated by mechanical forces transduced from the shoot to the root. We also show that exogenous application of gibberellic acid stimulates thickening of lignified cell types in the root, including cortical sclerenchyma, but is not sufficient to establish sclerenchyma identity in cortex cells. Leveraging the ability to manipulate cortex development via mechanical stimulus, we show that cortical sclerenchyma development alters root mechanical properties and improves resistance to lodging. We describe transcriptome changes associated with cortical sclerenchyma development under both ambient and mechanically stimulated conditions and identify SECONDARY WALL NAC7 as a putative regulator of mechanically responsive cortex cell wall development at the root base.

plant biology↗