Biology subjects

Gibbs, D. J.

Publications and source records attributed to Gibbs, D. J..

4 recordsLinked to original sources

bioRxiv2026

An oxygen-sensing Polycomb-group protein encodes flooding stress memory in plants

Most organisms, including plants, can encode stress memories that improve resilience to repeated environmental challenges. Flooding events expose plants to recurrent hypoxia, yet whether plants establish an adaptive memory of flooding is unclear. Here we show that somatic flooding stress memory is a conserved feature across multiple angiosperm species. In Arabidopsis, this memory depends on the oxygen-sensitive Polycomb Repressive Complex 2 (PRC2) subunit VERNALIZATION2 (VRN2). Loss of VRN2 impairs epigenetic memory formation and disrupts transcriptional memory at key genes that promote anthocyanin accumulation and repress leaf senescence, adaptive responses that enhance flooding tolerance. Collectively, we reveal a molecular mechanism where VRN2-PRC2 acts as both an oxygen sensor and chromatin effector to establish adaptive flooding stress memory in plants. ShortOur work defines a molecular mechanism for flooding stress memory in plants, actioned via the PRC2 subunit VRN2, that acts as the direct molecular (low) oxygen sensor and transducer. Coupled to its role in cold sensing, this identifies VRN2 as a master sensor subunit of the plant PRC2 that integrates multiple environmental cues to modulate the chromatin landscape and encode environmental memory.

plant biology↗

bioRxiv2024

VRN2-PRC2 facilitates light-triggered repression of PIF signalling to coordinate growth in Arabidopsis

The polycomb protein VERNALIZATION2 (VRN2) is a plant-specific subunit of the polycomb repressive complex 2 (PRC2), a conserved eukaryotic holoenzyme that represses gene expression by depositing the histone H3K27me3 mark in chromatin. Previous work established VRN2 as an oxygen-regulated target of the N-degron pathway that may function as a sensor subunit connecting PRC2 activity to the perception of positional and environmental cues. Here we show that VRN2 is enriched in hypoxic meristematic regions and emerging leaves of Arabidopsis under non-stressed conditions, and that vrn2 mutants are larger than wild type, indicating that VRN2-PRC2 negatively regulates growth and development. This growth phenotype is caused by ectopic expression of genes that promote cell expansion, including many SAUR genes and other direct PIF transcription factor targets. Analysis of SAUR19 promoter activity and expression dynamics revealed that VRN2 is required to specifically repress these genes in the light. Moreover, we show that VRN2 is epistatic to PIF4, and directly binds and methylates histones of key loci in the PIF4 transcriptional network to provide robust light-responsive control of gene expression and growth. We propose that hypoxia-stabilised VRN2-PRC2 sets a conditionally repressed chromatin state at PIF-regulated hub genes early in leaf ontogeny coinciding with the cell division phase, and that this is required for enhancing their subsequent repression via a light-responsive signalling cascade as cells enter the expansion phase. Thus, we have identified VRN2-PRC2 as core component of a spatially regulated and developmentally encoded epigenetic mechanism that co-ordinates environment-responsive growth by facilitating light-triggered suppression of PIF signalling.

plant biology↗

bioRxiv2020

The Arabidopsis NOT4A E3 ligase coordinates PGR3 expression to regulate chloroplast protein translation

Chloroplast function requires the coordinated action of nuclear- and chloroplast-derived proteins, including several hundred nuclear-encoded pentatricopeptide repeat (PPR) proteins that regulate plastid mRNA metabolism. Despite their large number and importance, regulatory mechanisms controlling PPR expression are poorly understood. Here we show that the Arabidopsis NOT4A ubiquitin-ligase positively regulates PROTON GRADIENT 3 (PGR3), a PPR protein required for translating 30S ribosome subunits and several thylakoid-localised photosynthetic components within chloroplasts. Loss of NOT4A function leads to a strong depletion of plastid ribosomes, which reduces mRNA translation and negatively impacts photosynthetic capacity, causing pale-yellow and slow-growth phenotypes. Quantitative transcriptome and proteome analyses reveal that these defects are due to a lack of PGR3 expression in not4a, and we show that normal plastid function is restored through transgenic PGR3 expression. Our work identifies NOT4A as crucial for ensuring robust photosynthetic function during development and stress-response, through modulating PGR3 levels to coordinate chloroplast protein synthesis.

plant biology↗

bioRxiv2019

Ethylene-mediated nitric oxide depletion pre-adapts plants to hypoxia stress

Timely perception of adverse environmental changes is critical for survival. Dynamic changes in gases are important cues for plants to sense environmental perturbations, such as submergence. In Arabidopsis thaliana, changes in oxygen and nitric oxide (NO) control the stability of ERFVII transcription factors. ERFVII proteolysis is regulated by the N-degron pathway and mediates adaptation to flooding-induced hypoxia. However, how plants detect and transduce early submergence signals remains elusive. Here we show that plants can rapidly detect submergence through passive ethylene entrapment and use this signal to pre-adapt to impending hypoxia. Ethylene can enhance ERFVII stability prior to hypoxia by increasing the NO-scavenger PHYTOGLOBIN1. This ethylene-mediated NO depletion and consequent ERFVII accumulation pre-adapts plants to survive subsequent hypoxia. Our results reveal the biological link between three gaseous signals for the regulation of flooding survival and identifies novel regulatory targets for early stress perception that could be pivotal for developing flood-tolerant crops.

plant biology↗