Biology subjects

Gully, K.

Publications and source records attributed to Gully, K..

7 recordsLinked to original sources

bioRxiv2025

GWAs reveals SUBER GENE1-mediated suberization via Type One Phosphatases

Suberin deposition in the root endodermis is critical for plant nutrient acquisition and environmental adaptation. Here, we used an unbiased forward genetic approach based on natural variation across 284 Arabidopsis thaliana accessions to identify novel regulators of endodermal suberization. This screen revealed striking diversity in suberin levels and patterns, uncovering broader roles for suberin beyond those observed in the reference accession Col-0. A genome-wide association study pinpointed SUBER GENE1 (SBG1), a previously uncharacterized gene encoding a 129-amino acid protein, as a key regulator of suberin deposition. SBG1 acts through physical interaction with type one protein phosphatases (TOPPs) via conserved SILK and RVxF motifs. Disrupting this interaction abolishes SBG1 function, while topp mutants exhibit enhanced endodermal suberization, mirroring SBG1 overexpression. Our findings uncover a previously unknown regulatory module linking suberin formation to TOPP activity and ABA signaling and provide a framework for improving plant stress resilience through targeted manipulation of root barrier properties.

plant biology↗

bioRxiv2024

Temperature-dependent polar lignification of a seed coat suberin layer promoting dormancy in Arabidopsis thaliana

The seed is a landmark plant adaptation where the embryo is sheltered by a protective seed coat to facilitate dispersion. In Arabidopsis, the seed coat, derived from ovular integuments, plays a critical role in maintaining dormancy, ensuring germination occurs during a favorable season. Dormancy is enhanced by cold temperatures during seed development by affecting seed coat permeability through changes in apoplastic barriers. However, the localization and composition of these apoplastic barriers are poorly understood. This study identifies and investigates a polar barrier in the seed coats outer integument (oi1) cells. We present histological, biochemical, and genetic evidence showing that cold promotes polar seed coat lignification of the outer integument 1 (oi1) cells and suberization throughout the entire oi1 cell boundary. The polar oi1 barrier is regulated by the transcription factors MYB107 and MYB9. MYB107, in particular, is crucial for the lignified polar oi1 barrier formation under cold temperatures. The absence of the oi1 barrier in mutant seeds correlates with increased permeability and reduced dormancy. Our findings elucidate how temperature-induced modifications in seed coat composition regulate dormancy, highlighting the roles of suberin and lignin in this process. Significance statementOur study uncovers how cold temperatures during seed development in the mother plant influence seed dormancy through apoplastic modifications in the Arabidopsis thaliana seed coat. We identified a polar lignin barrier in the outer integument 1 (oi1) cells, which are also suberized. Lignification and suberization are regulated by transcription factors MYB107 and MYB9. Cold promotes lignification and suberization of oi1 cells through MYB107, thus creating a "memory" that reduces seed permeability and strengthens dormancy. Mutants defective in the oi1 barrier exhibit lower dormancy, highlighting the adaptive importance of this barrier. These findings advance our understanding of temperature-induced seed coat adaptations and their agricultural implications, particularly in the context of climate change, offering valuable insights for improving crop resilience and yield.

plant biology↗

bioRxiv2024

The GPAT4/6/8 clade functions in Arabidopsis root suberization non-redundantly with the GPAT5/7 clade required for suberin lamellae

SummaryLipid polymers such as cutin and suberin strengthen the diffusion barrier properties of the cell wall in specific cell types and are essential for water relations, mineral nutrition, and stress protection in plants. Land plant-specific glycerol-3-phosphate acyltransferases (GPATs) of different clades are central players in cutin and suberin monomer biosynthesis. Here, we show that the GPAT4/6/8 clade in Arabidopsis thaliana, which is known to mediate cutin formation, is also required for developmentally regulated root suberization, in addition to the established roles of GPAT5/7 in suberization. The GPAT5/7 clade is mainly required for abscisic acid-regulated suberization. In addition, the GPAT5/7 clade is crucial for the formation of the typical lamellated suberin ultrastructure observed by transmission electron microscopy, as distinct amorphous globular polyester structures were deposited in the apoplast of the gpat5 gpat7 double mutant, in contrast to the thinner but still lamellated suberin deposition in the gpat4 gpat6 gpat8 triple mutant. The intrinsic phosphatase activity of GPAT4, GPAT6, and GPAT8, which leads to monoacylglycerol biosynthesis, may be important for suberin biosynthesis. GPAT5/7 lack an active phosphatase domain. Notably, gpat5 gpat7 phenotypes were partially reverted by treatment with a phosphatase inhibitor or the expression of phosphatase-dead variants of GPAT4/6/8. Thus, GPATs that lack an active phosphatase domain, which are predicted to synthetize lysophosphatidic acids, might be crucial for the formation of the lamellated structure of suberin. GPATs with active and non-active phosphatase domains appear to have non-redundant functions and must cooperate to achieve the efficient biosynthesis of correctly structured suberin. Significance statementThe establishment of proper lamellated suberin in roots plays essential roles in regulating mineral nutrition and water relations in plants. The basis for the macromolecular arrangement determining the ultrastructure and properties of suberin lamellae is unknown. Here, we report that both the GPAT4/6/8 and GPAT5/7 clades of glycerol-3-phosphate acyltransferases (GPATs) contribute to suberin formation in Arabidopsis roots. In addition, we reveal that the GPAT5/7 clade is required for the formation of the lamellated suberin ultrastructure. Several lines of evidence suggest that the loss of phosphatase activity in GPATs might have played a crucial role in the formation of suberin lamellae during evolution.

plant biology↗

bioRxiv2023

Vaccine-mediated protection against merbecovirus and sarbecovirus challenge in mice

The emergence of three distinct highly pathogenic human coronaviruses - SARS-CoV in 2003, MERS-CoV in 2012, and SARS-CoV-2 in 2019 - underlines the need to develop broadly active vaccines against the Merbecovirus and Sarbecovirus betacoronavirus subgenera. While SARS-CoV-2 vaccines are highly protective against severe COVID-19 disease, they do not protect against other sarbecoviruses or merbecoviruses. Here, we vaccinate mice with a trivalent sortase-conjugate nanoparticle (scNP) vaccine containing the SARS-CoV-2, RsSHC014, and MERS-CoV receptor binding domains (RBDs), which elicited live-virus neutralizing antibody responses and broad protection. Specifically, a monovalent SARS-CoV-2 RBD scNP vaccine only protected against sarbecovirus challenge, whereas the trivalent RBD scNP vaccine protected against both merbecovirus and sarbecovirus challenge in highly pathogenic and lethal mouse models. Moreover, the trivalent RBD scNP elicited serum neutralizing antibodies against SARS-CoV, MERS-CoV and SARS-CoV-2 BA.1 live viruses. Our findings show that a trivalent RBD nanoparticle vaccine displaying merbecovirus and sarbecovirus immunogens elicits immunity that broadly protects mice against disease. This study demonstrates proof-of-concept for a single pan-betacoronavirus vaccine to protect against three highly pathogenic human coronaviruses spanning two betacoronavirus subgenera.

immunology↗

bioRxiv2021

Early therapy with remdesivir and antibody combinations improves COVID-19 disease in mice

Improving the standard of clinical care for individuals infected with SARS-CoV-2 variants is a global health priority. Small molecule antivirals like remdesivir (RDV) and biologics such as human monoclonal antibodies (mAb) have demonstrated therapeutic efficacy against SARS-CoV-2, the causative agent of COVID-19. However, it is not known if combination RDV/mAb will improve outcomes over single agent therapies or whether antibody therapies will remain efficacious against variants. In kinetic studies in a mouse-adapted model of ancestral SARS-CoV-2 pathogenesis, we show that a combination of two mAbs in clinical trials, C144 and C135, have potent antiviral effects against even when initiated 48 hours after infection. The same antibody combination was also effective in prevention and therapy against the B.1.351 variant of concern (VOC). Combining RDV and antibodies provided a modest improvement in outcomes compared to single agents. These data support the continued use of RDV to treat SARS-CoV-2 infections and support the continued clinical development of the C144 and C135 antibody combination to treat patients infected with SARS-CoV-2 variants.

microbiology↗

bioRxiv2021

Suberin plasticity to developmental and exogenous cues is regulated by a set of MYB transcription factors

Suberin is a hydrophobic biopolymer that can be deposited at the periphery of cells, forming protective barriers against biotic and abiotic stress. In roots, suberin forms lamellae at the periphery of endodermal cells where it plays crucial roles in the control of water and mineral transport. Suberin formation is highly regulated by developmental and environmental cues. However, the mechanisms controlling its spatiotemporal regulation are poorly understood. Here, we show that endodermal suberin is regulated independently by developmental and exogenous signals to fine tune suberin deposition in roots. We found a set of four MYB transcription factors (MYB41, MYB53, MYB92 and MYB93), that are regulated by these two signals, and are sufficient to promote endodermal suberin. Mutation of these four transcription factors simultaneously through genome editing, lead to a dramatic reduction of suberin formation in response to both developmental and environmental signals. Most suberin mutants analyzed at physiological levels are also affected in another endodermal barrier made of lignin (Casparian strips), through a compensatory mechanism. Through the functional analysis of these four MYBs we generated plants allowing unbiased investigations of endodermal suberin function without accounting for confounding effects due to Casparian strip defects, and could unravel specific roles of suberin in nutrient homeostasis.

plant biology↗

bioRxiv2020

GDSL-domain containing proteins mediate suberin biosynthesis and degradation, enabling developmental plasticity of the endodermis during lateral root emergence

ABSTRACTRoots anchor plants and deliver water and nutrients from the soil. The root endodermis provides the crucial extracellular diffusion barrier by setting up a supracellular network of lignified cell walls, called Casparian strips, supported by a subsequent formation of suberin lamellae. Whereas lignification is thought to be irreversible, formation of suberin lamellae was demonstrated to be dynamic, facilitating adaptation to different soil conditions. Plants shape their root system through the regulated formation of lateral roots emerging from within the endodermis, requiring local breaking and re-sealing of the endodermal diffusion barriers. Here, we show that differentiated endodermal cells have a distinct auxin-mediated transcriptional response that regulates cell wall remodelling. Based on this data set we identify a set of GDSL-lipases that are essential for suberin formation. Moreover, we find that another set of GDSL-lipases mediates suberin degradation, which enables the developmental plasticity of the endodermis required for normal lateral root emergence.Competing Interest StatementThe authors have declared no competing interest.View Full Text

plant biology↗