Biology subjects

George, W.

Publications and source records attributed to George, W..

5 recordsLinked to original sources

bioRxiv2025

Natural variation in expression of a plant immune receptor mediates elicitor sensitivity

Plant immune systems rely on pattern recognition receptors (PRRs) to specifically detect diverse pathogen/pest-associated molecular patterns (PAMPs). While many distinct receptors are known to mediate PAMP recognition, the role of transcriptional regulation of PRRs remains poorly understood. In legume plants, Inceptin Receptor (INR) senses an 11-amino acid peptide, In11, to activate direct and indirect defenses against caterpillar pests. Here we investigated the genetic basis of the rare In11 insensitivity phenotype found in common bean (Phaseolus vulgaris) landraces. Natural variation in the rapid In11-induced ethylene response corresponded with genetic variation at the locus encoding INR itself. Surprisingly, phenotypic variation corresponded with expression level of the INR receptor, rather than coding sequence variation. Promoter sequence variation across 21 accessions of Andean Phaseolus vulgaris, as well as near-isogenic lines (NILs) derived from crosses between an In11-sensitive and insensitive line, corresponded with strength of In11-induced ethylene response. Promoter alleles also corresponded with strength of activation of a luciferase reporter in the heterologous expression model, Nicotiana benthamiana, indicating that cis-element variation is sufficient to drive differences in leaf expression levels. Surprisingly, NILs encoding either WT or the lower expression inr-2 allele did not show differences in resistance to herbivory by beet armyworm (Spodoptera exigua), or in In11-pretreatment protection assays, suggesting that even low INR expression can still mediate effective responses against herbivores despite insensitivity to the In11 elicitor in laboratory assays. Our results demonstrate that natural variation in PRR expression can contribute to differential PAMP responses while not necessarily affecting downstream resistance phenotypes.

plant biology↗

bioRxiv2025

Unusually Broad-spectrum small-molecule sensing using a single protein scaffold

Small-molecule sensing in plants is dominated by chemical-induced dimerization modules. In the abscisic acid (ABA) system, allosteric receptors recruit phosphatase effectors and achieve nM in vivo responses from {micro}M receptor-ligand interactions. This sensitivity amplification could enable ABA receptors to serve as generic scaffolds for designing small-molecule sensors. To test this, we screened collections of mutant ABA-receptors against 2,726 drugs and other ligands and identified 569 sensors for 6.7% of these ligands. The mutational patterns indicate strong selection for ligand-specific binding pockets. We used these data to develop a sensor design pipeline and isolated sensors for multiple plant natural products, 2,4,6-trinitrotoluene (TNT), and "forever" per- and polyfluoroalkyl substances (PFAS). Thus, the ABA sensor system enables design and isolation of small-molecule sensors with broad chemical scope and antibody-like simplicity.

synthetic biology↗

bioRxiv2024

A history-dependent integrase recorder of plant gene expression with single cell resolution

During development, most cells experience a progressive restriction of fate that ultimately results in a fully differentiated mature state. Understanding more about the gene expression patterns that underlie developmental programs can inform engineering efforts for new or optimized forms. Here, we present a four-state integrase-based recorder of gene expression history and demonstrate its use in tracking gene expression events in Arabidopsis thaliana in two developmental contexts: lateral root initiation and stomatal differentiation. The recorder uses two serine integrases to mediate sequential DNA recombination events, resulting in step-wise, history-dependent switching between expression of fluorescent reporters. By using promoters that express at different times along each of the two differentiation pathways to drive integrase expression, we successfully tied fluorescent status to an ordered progression of gene expression along the developmental trajectory. In one snapshot of a mature tissue, our recorder was able to reveal past gene expression with single cell resolution. In this way, we were able to capture heterogeneity in stomatal development, confirming the existence of two alternate paths of differentiation.

synthetic biology↗

bioRxiv2024

An N-terminal domain specifies developmental control by the SMAX1-LIKE family of transcriptional co-repressors in Arabidopsis thaliana

SMAX1-LIKE (SMXL) proteins are transcriptional co-repressors that regulate many aspects of plant growth and development. Proteins from the SMAX1- and SMXL78-clades of this family are targeted for degradation after karrikin or strigolactone perception, triggering downstream responses. We investigated how SMXL proteins control development. SMXL7 can partially replicate SMAX1 function in seeds and seedlings, but SMAX1 cannot replace SMXL7 in shoot branching control. Therefore, the distinct roles of these genes arise from differences in protein activity more than expression. Analysis of chimeras and domain deletions of SMAX1 and SMXL7 proteins revealed that an N-terminal domain is necessary and sufficient to specify developmental functions. We screened 158 transcription factors for interactions with SMAX1. The N-terminal domain is necessary and/or sufficient for the majority of candidate interactions. These discoveries enable cross-wiring of karrikin and strigolactone control of plant development and lay a foundation for understanding how SMXL proteins evolved functional differences.

plant biology↗

bioRxiv2020

A single cell view of the transcriptome during lateral root initiation in Arabidopsis thaliana

Root architecture is a major determinant of fitness, and is under constant modification in response to favorable and unfavorable environmental stimuli. Beyond impacts on the primary root, the environment can alter the position, spacing, density and length of secondary or lateral roots. Lateral root development is among the best-studied examples of plant organogenesis, yet there are still many unanswered questions about its earliest steps. Among the challenges faced in capturing these first molecular events is the fact that this process occurs in a small number of cells with unpredictable timing. Single-cell sequencing methods afford the opportunity to isolate the specific transcriptional changes occurring in cells undergoing this fate transition. Using this approach, we successfully captured the transcriptomes of initiating lateral root primordia, and discovered many previously unreported upregulated genes associated with this process. We developed a method to selectively repress target gene transcription in the xylem pole pericycle cells where lateral roots originate, and demonstrated that expression of several of these targets was required for normal root development. We also discovered novel subpopulations of cells in the pericycle and endodermal cell files that respond to lateral root initiation, highlighting the coordination across cell files required for this fate transition. One sentence summarySingle cell RNA sequencing reveals new molecular details about lateral root initiation, including the transcriptional impacts of the primordia on bordering cells.

plant biology↗