ORCID Profile
0000-0002-0770-2684
Current Organisation
Saint Mary's University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: MDPI AG
Date: 19-09-2023
Publisher: Proceedings of the National Academy of Sciences
Date: 19-03-2014
Abstract: The legume/rhizobia symbiosis involves a root-based exchange of bacterial fixed nitrogen for plant-derived photosynthetic carbon. The exchange takes place within the legume root nodule, which is a specialized root tissue that develops in response to plant and bacterial signal exchange. The bacteria reside within plant cells inside the nodule. In this study, we explore the activity of a membrane-bound soybean transcription factor, Glycine max basic–helix-loop–helix membrane 1, which is important for soybean nodule growth and is linked to the activity of a unique class of ammonium channels and to signaling cascades influencing a nodule circadian clock.
Publisher: Wiley
Date: 21-01-2016
DOI: 10.1111/NPH.13837
Abstract: In root nodules rhizobia enter host cells via infection threads. The release of bacteria to a host cell is possible from cell wall‐free regions of the infection thread. We hypothesized that the VAMP 721d and VAMP 721e exocytotic pathway, identified before in Medicago truncatula , has a role in the local modification of cell wall during the release of rhizobia. To clarify the role of VAMP 721d and VAMP 721e we used Glycine max , a plant with a determinate type of nodule. The localization of the main polysaccharide compounds of primary cell walls was analysed in control vs nodules with partially silenced Gm VAMP 721d . The silencing of Gm VAMP 721d blocked the release of rhizobia. Instead of rhizobia‐containing membrane compartments – symbiosomes – the infected cells contained big clusters of bacteria embedded in a matrix of methyl‐esterified and de‐methyl‐esterified pectin. These clusters were surrounded by a membrane. We found that Gm VAMP 721d ‐ positive vesicles were not transporting methyl‐esterified pectin. We hypothesized that they may deliver the enzymes involved in pectin turnover. Subsequently, we found that Gm VAMP 721d is partly co‐localized with pectate lyase. Therefore, the biological role of VAMP 721d may be explained by its action in delivering pectin‐modifying enzymes to the site of release.
Publisher: Springer Science and Business Media LLC
Date: 12-07-2019
DOI: 10.1038/S41598-019-46171-2
Abstract: Assembling composite DNA modules from custom DNA parts has become routine due to recent technological breakthroughs such as Golden Gate modular cloning. Using Golden Gate, one can efficiently assemble custom transcription units and piece units together to generate higher-order assemblies. Although Golden Gate cloning systems have been developed to assemble DNA plasmids required for experimental work in model species, they are not typically applicable to organisms from other kingdoms. Consequently, a typical molecular biology laboratory working across kingdoms must use multiple cloning strategies to assemble DNA constructs for experimental assays. To simplify the DNA assembly process, we developed a multi-kingdom (MK) Golden Gate assembly platform for experimental work in species from the kingdoms Fungi, Eubacteria, Protista, Plantae, and Animalia. Plasmid backbone and part overhangs are consistent across the platform, saving both time and resources in the laboratory. We demonstrate the functionality of the system by performing a variety of experiments across kingdoms including genome editing, fluorescence microscopy, and protein interaction assays. The versatile MK system therefore streamlines the assembly of modular DNA constructs for biological assays across a range of model organisms.
Publisher: Springer Science and Business Media LLC
Date: 02-2004
Publisher: Wiley
Date: 04-11-2010
DOI: 10.1016/J.FEBSLET.2010.10.059
Abstract: Calmodulin(CaM)-regulated protein phosphorylation forms an important component of Ca(2+) signaling in animals but is less understood in plants. We have identified a CaM-binding receptor-like kinase from soybean nodules, GmCaMK1, a homolog of Arabidopsis CRLK1. We delineated the CaM-binding domain (CaMBD) of GmCaMK1 to a 24-residue region near the C-terminus, which overlaps with the kinase domain. We have demonstrated that GmCaMK1 binds CaM with high affinity in a Ca(2+)-dependent manner. We showed that GmCaMK1 is expressed broadly across tissues and is enriched in roots and developing nodules. Finally, we examined the CaMBDs of the five-member GmCaMK family in soybean, and orthologs present across taxa.
Publisher: eLife Sciences Publications, Ltd
Date: 21-09-2017
DOI: 10.7554/ELIFE.25012
Abstract: The coordinated control of Ca2+ signaling is essential for development in eukaryotes. Cyclic nucleotide-gated channel (CNGC) family members mediate Ca2+ influx from cellular stores in plants (Charpentier et al., 2016 Gao et al., 2016 Frietsch et al., 2007 Urquhart et al., 2007). Here, we report the unusual genetic behavior of a quantitative gain-of-function CNGC mutation (brush) in Lotus japonicus resulting in a leaky tetrameric channel. brush resides in a cluster of redundant CNGCs encoding subunits which resemble metazoan voltage-gated potassium (Kv1-Kv4) channels in assembly and gating properties. The recessive mongenic brush mutation impaired root development and infection by nitrogen-fixing rhizobia. The brush allele exhibited quantitative behavior since overexpression of the cluster subunits was required to suppress the brush phenotype. The results reveal a mechanism by which quantitative competition between channel subunits for tetramer assembly can impact the phenotype of the mutation carrier.
Publisher: eLife Sciences Publications, Ltd
Date: 14-09-2017
Publisher: Public Library of Science (PLoS)
Date: 03-02-2023
DOI: 10.1371/JOURNAL.PGEN.1010621
Abstract: Symbiotic interactions between rhizobia and legumes result in the formation of root nodules, which fix nitrogen that can be used for plant growth. Rhizobia usually invade legume roots through a plant-made tunnel-like structure called an infection thread (IT). RPG (Rhizobium-directed polar growth) encodes a coiled-coil protein that has been identified in Medicago truncatula as required for root nodule infection, but the function of RPG remains poorly understood. In this study, we identified and characterized RPG in Lotus japonicus and determined that it is required for IT formation. RPG was induced by Mesorhizobium loti or purified Nodulation factor and displayed an infection-specific expression pattern. Nodule inception (NIN) bound to the RPG promoter and induced its expression. We showed that RPG displayed punctate subcellular localization in L . japonicus root protoplasts and in root hairs infected by M . loti . The N-terminal predicted C2 lipid-binding domain of RPG was not required for this subcellular localization or for function. CERBERUS, a U-box E3 ligase which is also required for rhizobial infection, was found to be localized similarly in puncta. RPG co-localized and directly interacted with CERBERUS in the early endosome (TGN/EE) compartment and near the nuclei in root hairs after rhizobial inoculation. Our study sheds light on an RPG-CERBERUS protein complex that is involved in an exocytotic pathway mediating IT elongation.
Publisher: Cold Spring Harbor Laboratory
Date: 07-2022
DOI: 10.1101/2022.06.30.498293
Abstract: Symbiotic interactions between rhizobia and legumes result in the formation of root nodules, which fix nitrogen that can be used for plant growth. Rhizobia usually invade legume roots through a plant-made tunnel-like structure called an infection thread (IT). Rhizobium-directed polar growth ( RPG ) encodes a coiled-coil protein that was identified in Medicago truncatula as required for root nodule infection, but the function of RPG remains poorly understood. In this study, we identified and characterized RPG in Lotus japonicus and determined that it is required for IT formation. RPG was induced by Mesorhizobium loti or purified Nodulation factor and displayed an infection-specific expression pattern. Nodule inception (NIN) bound to the RPG promoter and induced its expression. A GFP-RPG protein was localized in puncta subcellular localization in L. japonicus root protoplasts and in root hairs infected by M. loti . The N-terminal predicted C2 lipid-binding domain of RPG was not required for this subcellular localization or for function. CERBERUS, a U-box E3 ligase which is also required for rhizobial infection, was found to be localized in similar puncta. RPG co-localized and directly interacted with CERBERUS at the early endosomes (TGN/EE) compartment and near the nuclei in root hairs after rhizobia inoculation. Our study sheds light on that a RPG-CERBERUS protein complex that is involved in an exocytotic pathway mediating IT polarity growth which is driven by nuclear migration. Puncta localization RPG-CERBERUS protein complex promote polarity growth of ITs driven by nuclear migration.
Publisher: Springer Science and Business Media LLC
Date: 08-2005
DOI: 10.1007/S11103-005-8395-X
Abstract: Complex signal transduction pathways underlie the myriad plant responses to attack by pathogens. Ca(2+) is a universal second messenger in eukaryotes that modulates various signal transduction pathways through stimulus-specific changes in its intracellular concentration. Ca(2+)-binding proteins such as calmodulin (CaM) detect Ca(2+) signals and regulate downstream targets as part of a coordinated cellular response to a given stimulus. Here we report the characterization of a tomato gene (APR134) encoding a CaM-related protein that is induced in disease-resistant leaves in response to attack by Pseudomonas syringae pv. tomato. We show that suppression of APR134 gene expression in tomato (Solanum lycopersicum), using virus-induced gene silencing (VIGS), compromises the plant's immune response. We isolated APR134-like genes from Arabidopsis, termed CML42 and CML43, to investigate whether they serve a functionally similar role. Gene expression analysis revealed that CML43 is rapidly induced in disease-resistant Arabidopsis leaves following inoculation with Pseudomonas syringae pv. tomato. Overexpression of CML43 in Arabidopsis accelerated the hypersensitive response. Recombinant APR134, CML42, and CML43 proteins all bind Ca(2+ )in vitro. Collectively, our data support a role for CML43, and APR134 as important mediators of Ca(2+)-dependent signals during the plant immune response to bacterial pathogens.
Publisher: EMBO
Date: 08-2019
Publisher: Wiley
Date: 17-05-2017
DOI: 10.1111/NPH.14599
Abstract: Plants sense microbial signatures via activation of pattern recognition receptors ( PPR s), which trigger a range of cellular defences. One response is the closure of plasmodesmata, which reduces symplastic connectivity and the capacity for direct molecular exchange between host cells. Plasmodesmal flux is regulated by a variety of environmental cues but the downstream signalling pathways are poorly defined, especially the way in which calcium regulates plasmodesmal closure. Here, we identify that closure of plasmodesmata in response to bacterial flagellin, but not fungal chitin, is mediated by a plasmodesmal‐localized Ca 2+ ‐binding protein Calmodulin‐like 41 ( CML 41). CML 41 is transcriptionally upregulated by flg22 and facilitates rapid callose deposition at plasmodesmata following flg22 treatment. CML 41 acts independently of other defence responses triggered by flg22 perception and reduces bacterial infection. We propose that CML 41 enables Ca 2+ ‐signalling specificity during bacterial pathogen attack and is required for a complete defence response against Pseudomonas syringae .
Publisher: Elsevier BV
Date: 11-2009
Publisher: Portland Press Ltd.
Date: 10-12-2013
DOI: 10.1042/BJ20131080
Abstract: Many signalling pathways in plants are regulated by the second messenger calcium (Ca2+). In the standard model, Ca2+-sensor proteins, such as CaM (calmodulin), detect Ca2+ signals and subsequently regulate downstream targets to advance the signal transduction cascade. In addition to CaM, plants possess many CMLs (CaM-like proteins) that are predicted to function as Ca2+ sensors, but which remain largely uncharacterized. In the present study, we examined the biochemical properties, subcellular localization and tissue-specific distribution of Arabidopsis CML43. Our data indicate that CML43 displays characteristics typical of Ca2+ sensors, including high-affinity Ca2+ binding, conformational changes upon Ca2+ binding that expose hydrophobic regions and stabilization of structure in the presence of Mg2+ or Ca2+. In vivo localization analysis demonstrates that CML43 resides in cytosolic and nuclear compartments. Transgenic plants expressing a CML43:GUS (β-glucoronidase) promoter reporter gene revealed that CML43 promoter activity is restricted almost exclusively to root tips under normal growth conditions. GUS reporter activity in these transgenic plants was strongly increased when exposed to the defence compound SA (salicylic acid). Furthermore, immunoblot analysis revealed that the CML43 protein accumulates following treatment with SA. Collectively, our findings suggest that CML43 functions as a Ca2+ sensor in root tips during both normal growth and plant immune response.
Start Date: 2020
End Date: 2021
Funder: Natural Sciences and Engineering Research Council
View Funded ActivityStart Date: 2020
End Date: 2021
Funder: Natural Sciences and Engineering Research Council
View Funded Activity