Biology subjects

Denyer, T.

Publications and source records attributed to Denyer, T..

3 recordsLinked to original sources

bioRxiv2026

Autophagy acts as a spatial organizer of cell-type-specific plant immunity

Effective plant immunity requires precise spatial coordination of immune responses across cell-types to restrict pathogens while preventing tissue damage, yet the intracellular pathways that organize this spatial architecture remain unknown. Here we show that autophagy serves as a spatial coordinator of immunity, partitioning and calibrating immune strategies across tissues during Pseudomonas syringae infection in Arabidopsis thaliana. Combining single-cell transcriptomics, cell-type-specific complementation, and live-cell imaging, we uncover distinct and opposing roles of autophagy across tissues. In guard cells, autophagy promotes pathogen-induced stomatal reopening by suppressing abscisic acid (ABA) signalling in part via autophagic turnover of the guard cell ABA receptor PYL4. In contrast, in mesophyll cells, autophagy restricts immune activation while simultaneously enabling effective immune execution: its loss enhances EDS1-PAD4-ADR1 pathway expression yet compromises PTI outputs. Mechanistically, bacterial infection triggers autophagic EDS1 turnover, supporting a model in which controlled EDS1 recycling facilitates HR elicitation. Cell-type-specific complementation reveals that PTI competence may involve coordinated autophagy across tissues, whereas mesophyll-autonomous autophagy is partially sufficient for HR execution. Together, these findings establish a framework in which spatial control of proteostasis orchestrates multicellular immune coordination, with broad implications for understanding how conserved degradation pathways regulate layered immunity across organisms.

plant biology↗

bioRxiv2020

Unique and distinct identities and functions of leaf phloem cells revealed by single cell transcriptomics

AO_SCPLOWBSTRACTC_SCPLOWThe leaf vasculature plays a key role in solute translocation. Veins consist of at least seven distinct cell types, with specific roles in transport, metabolism, and signaling. Little is known about the vascular cells in leaves, in particular the phloem parenchyma (PP). PP effluxes sucrose into the apoplasm as a basis for phloem loading; yet PP has only been characterized microscopically. Here, we enriched vascular cells from Arabidopsis leaves to generate a single-cell transcriptome atlas of leaf vasculature. We identified [≥]19 cell clusters, encompassing epidermis, guard cells, hydathodes, mesophyll, and all vascular cell types, and used metabolic pathway analysis to define their roles. Clusters comprising PP cells were enriched for transporters, including SWEET11 and SWEET12 sucrose and UmamiT amino acid efflux carriers. PP development occurs independently from APL, a transcription factor required for phloem differentiation. PP cells have a unique pattern of amino acid metabolism activity distinct from companion cells (CC), explaining differential distribution/metabolism of amino acids in veins. The kinship relation of the vascular clusters is strikingly similar to the vein morphology, except for a clear separation of CC from the other vascular cells including PP. In summary, our scRNA-seq analysis provides a wide range of information into the leaf vasculature and the role and relationship of the leaf cell types.

plant biology↗

bioRxiv2020

Noxious effects of cell surface display glutamate sensors on plant growth and development

Plants use electrical and chemical signals for systemic communication. Herbivory, for instance, appears to trigger local apoplasmic glutamate accumulation, systemic electrical signals and calcium waves that travel to report insect damage to neighboring leaves and initiate defense. To monitor extra- and intracellular glutamate concentrations in plants, we generated Arabidopsis lines expressing genetically encoded fluorescent glutamate sensors. In contrast to cytosolically localized sensors, extracellularly displayed variants inhibited plant growth and proper development. Phenotypic analyses of high-affinity display sensor lines revealed that root meristem development, particularly the quiescent center (QC), number of lateral roots, vegetative growth and floral architecture were impacted. Notably, the severity of the phenotypes was positively correlated with the affinity of the display sensors, intimating that their ability to sequester glutamate at the surface of the plasma membrane was responsible for the defects. Root growth defects were suppressed by supplementing culture media with low levels of glutamate. Together, the data indicate that sequestration of glutamate at the cell surface either disrupts the supply of glutamate to meristematic cells and/or impairs localized glutamatergic signaling important for developmental processes. SIGNIFICANCE STATEMENTGlutamate is an important signaling molecule in animals and plants. The affinity-dependent effects of surface-displayed glutamate sensors on plant development intimate that glutamate levels in the vicinity of the plasma membrane play important roles in signaling in plants.

plant biology↗