Biology subjects

Hawes, C.

Publications and source records attributed to Hawes, C..

6 recordsLinked to original sources

bioRxiv2023

Floral presence and flower identity alter cereal aphid endosymbiont communities on adjacent crops

O_LIFloral plantings adjacent to crops fields can recruit populations of natural enemies by providing flower nectar and non-crop prey to increase natural pest regulation. Observed variation in success rates might be due to changes in the unseen community of protective endosymbionts hosted by many herbivorous insects, which can confer resistance to various specialist natural enemies, e.g. parasitoid wasps. Reduced insect control may occur if highly protective symbiont combinations increase in frequency via selection effects, and this is expected to be stronger in lower diversity systems. C_LIO_LIWe used a large-scale field trial to analyse the bacterial endosymbiont communities hosted by cereal aphids (Sitobion avenae) collected along transects into strip plots of barley plants managed by either conventional or integrated (including floral field margins and reduced inputs) methods. In addition, we conducted an outdoor pot experiment to analyse endosymbionts in S. avenae aphids collected on barley plants that were either grown alone or alongside one of three flowering plants, across three time points. C_LIO_LIIn the field, aphids hosted up to four symbionts. The abundance of aphids and parasitoid wasps was reduced towards the middle of all fields while aphid symbiont species richness and diversity decreased into the field in conventional, but not integrated, field-strips. The proportion of aphids hosting different symbiont combinations varied across cropping systems, with distances into the fields, and were correlated with parasitoid wasp abundances. C_LIO_LIIn the pot experiment, aphids hosted up to six symbionts. Flower presence increased natural enemy abundance and diversity, and decreased aphid abundance. The proportion of aphids hosting different symbiont combinations varied across the flower treatment and time, and were correlated with varying abundances of the different specialist parasitoid wasp species recruited by different flowers. C_LIO_LISynthesis and applications. Floral plantings and flower identity can have community-wide impacts on the combinations of bacterial endosymbionts hosted by herbivorous insects. Our work highlights the potential of within-season selection for symbiont-mediated pest resistance to natural enemies with biological control impacts. This could be mitigated through increased recruitment of diverse natural enemies by incorporating functional diversity of floral resources into the environment. C_LI

ecology↗

bioRxiv2018

The cell wall regulates dynamics and size of plasma-membrane nanodomains in Arabidopsis.

Plant plasma-membrane (PM) proteins are involved in several vital processes, such as detection of pathogens, solute transport and cellular signalling. Recent models suggest that for these proteins to function effectively there needs to be structure within the PM allowing, for example, proteins in the same signalling cascade to be spatially organized. Here we demonstrate that several proteins with divergent functions are located in clusters of differing size in the membrane using sub-diffraction-limited Airyscan confocal microscopy. In addition, single particle tracking reveals that these proteins move at different rates within the membrane. We show that the actin and microtubule cytoskeletons appear to significantly regulate the mobility of one of these proteins (the pathogen receptor FLS2) and we further demonstrate that the cell wall is critical for the regulation of cluster size by affecting single particle dynamics of two proteins with key roles in morphogenesis (PIN3) and pathogen perception (FLS2). We propose a model in which the cell wall and cytoskeleton are pivotal for differentially regulating protein cluster size and dynamics thereby contributing to the formation and functionality of membrane nanodomains.\n\nOne sentence summarySize and mobility of protein nanodomains in the plant plasma-membrane are regulated by interaction with the cell wall extracellular matrix.\n\nSignificance statementThe plant plasma membrane acts as the front line for cellular perception of the environment. As such, a large number of signalling and transport proteins which perceive or transport environmental signals, developmental cues and nutrients are located within it. Recently, a number of studies have revealed that proteins located within the plasma membrane do not simply freely diffuse within its plane. Rather, proteins are localized in nanometer sized structures called nanodomains. In addition to the plasma-membrane, plant cells also have an extracellular matrix, the cell wall. Here we have shown that the cell wall has a role in regulating the dynamics and size of plasma membrane nanodomains for proteins involved in morphogenesis (PIN3) and pathogen perception (FLS2).

cell biology↗

bioRxiv2018

Is Actin Filament Sliding Responsible for Endoplasmic Reticulum and Golgi Movement?

The plant secretory pathway is responsible for the production of the majority of proteins and carbohydrates consumed on the planet. The early secretory pathway is composed of Golgi bodies and the endoplasmic reticulum (ER) and is highly mobile in plants with rapid remodelling of the ER network. The dynamics of the ER and Golgi bodies is driven by the actin cytoskeleton and myosin motor proteins play a key role in this. However, exactly how myosin motor proteins drive remodelling in plants is currently a contentious issue. Here, using a combination of live cell microscopy and over-expression of non-functional myosins we demonstrate that myosin motor proteins drive actin filament sliding and subsequently the dynamics of the secretory pathway.\n\nSummaryIn plants, the actin cytoskeleton and myosins are fundamental for normal dynamics of the endomembrane system and cytoplasmic streaming. We demonstrate that this is in part due to myosin driven sliding of actin filaments within a bundle. This generates, at least in part, the motive force required for cell dynamics in planta.

cell biology↗

bioRxiv2018

Arabidopsis Lunapark proteins are involved in ER cisternae formation

The plant endoplasmic reticulum (ER) is crucial to the maintenance of cellular homeostasis. The ER consists of a dynamic and continuously remodelling network of tubules and cisternae. Several conserved membrane proteins have been implicated in formation and maintenance of the ER network in plants, such as RHD3 and the reticulon family of proteins.\n\nDespite the recent work in mammalian and yeast cells, the detailed molecular mechanisms of ER network organisation in plants still remain largely unknown. Recently novel ER network-shaping proteins called Lunapark have been identified in yeast and mammalian cells.\n\nHere we identify two arabidopsis LNP homologues and investigate their subcellular localisation via confocal microscopy and potential function in shaping the ER network using protein-protein interaction assays and mutant analysis.\n\nWe show that AtLNP1 overexpression in tobacco leaf epidermal cells mainly labels the three-way junctions (trivia) of the ER network whereas AtLNP2 labels the whole ER. Overexpression of LNP proteins results in an increased abundance of ER cisternae and an lnp1lnp2 amiRNA line displays a less structured ER network.\n\nThus, we hypothesize that AtLNP1 and AtLNP2 are involved in determining the dynamic morphology of the plant ER, possibly by regulating the formation of ER cisternae.

plant biology↗

bioRxiv2017

The Odd One Out: Aabidopsis Reticulon 20 Has A Role In Lipid Biosynthesis

The family of reticulon proteins has been shown to be involved in a variety of functions in eukaryotic cells including tubulation of the endoplasmic reticulum (ER), formation of cell plates and primary plasmodesmata. Reticulons are integral ER membrane proteins characterised by a reticulon homology domain comprising four transmembrane domains which results in the reticulons sitting in the membrane in a W-topology. Here we report on a subgroup of reticulons with an extended N-terminal domain and in particular on arabidopsis reticulon 20. We show that reticulon 20 is located in a unique punctate pattern on the ER membrane. Its closest homologue reticulon 19 labels the whole ER. We show that mutants in RTN20 or RTN19, respectively, display a significant change in sterol composition in the roots indicating a role in lipid biosynthesis or regulation. A third homologue in this family - 3BETAHSD/D1- is localised to ER exit sites resulting in an intriguing location difference for the three proteins.

plant biology↗

bioRxiv2017

Stacks off tracks: A role for the golgin AtCASP in plant endoplasmic reticulum - Golgi apparatus tethering

The plant Golgi apparatus modifies and sorts incoming proteins from the endoplasmic reticulum (ER), and synthesises cell wall matrix material. Plant cells possess numerous motile Golgi bodies, which are connected to the ER by yet to be identified tethering factors. Previous studies indicated a role of cis-Golgi plant golgins (long coiled-coil domains proteins anchored to Golgi membranes) in Golgi biogenesis. Here we show a tethering role for the golgin AtCASP at the ER-Golgi interface. Using live-cell imaging, Golgi body dynamics were compared in Arabidopsis thaliana leaf epidermal cells expressing fluorescently tagged AtCASP, a truncated AtCASP-{Delta}CC lacking the coiled-coil domains, and the Golgi marker STtmd. Golgi body speed and displacement were significantly reduced in AtCASP-{Delta}CC lines. Using a dual-colour optical trapping system and a TIRF-tweezer system, individual Golgi bodies were captured in planta. Golgi bodies in AtCASP-{Delta}CC lines were easier to trap, and the ER-Golgi connection was more easily disrupted. Occasionally, the ER tubule followed a trapped Golgi body with a gap, indicating the presence of other tethering factors. Our work confirms that the intimate ER-Golgi association can be disrupted or weakened by expression of truncated AtCASP-{Delta}CC, and suggests that this connection is most likely maintained by a golgin-mediated tethering complex.\n\nHighlightHere we show that the Golgi-associated Arabidopsis thaliana protein AtCASP may form part of a golgin-mediated tethering complex involved in anchoring plant Golgi stacks to the endoplasmic reticulum (ER).

plant biology↗