Biology subjects

Taylor, N. L.

Publications and source records attributed to Taylor, N. L..

6 recordsLinked to original sources

bioRxiv2025

Barley (Hordeum vulgare) maintains tricarboxylic acid cycle activity without invoking the GABA shunt under salt stress

Plants maintain energy balance under salinity stress through increased respiration and energy use, processes also associated with reactive oxygen species generation. Although respiration imposes a high energy cost, mitochondrial respiration and the tricarboxylic acid (TCA) cycle activity are vital for ATP production and providing electron donors that drive ion exclusion and ROS detoxification. This study examined the molecular basis of respiratory responses to salinity in barley using physiological, biochemical, metabolomic, and proteomic analyses. Salt exposure resulted in sodium accumulation, decreased photosynthesis and biomass, and increased respiration. Metabolite profiling indicated activation of the TCA cycle, while proteomics showed increased abundance of all targeted TCA enzymes, including phosphoenolpyruvate carboxylase isoforms and succinate dehydrogenase. Enhanced pyruvate oxidation and accumulation of downstream metabolites suggested that the classical TCA cycle underpins barleys salinity tolerance. Conversely, reduced levels of 2-oxoglutarate and succinate implied limited activity of the GABA shunt. The absence of detectable arginine and ornithine, unlike their salt-induced increase in wheat, further indicated that the GABA shunt contributes minimally to barleys salinity tolerance. Overall, barley primarily relies on enhanced mitochondrial respiration and the canonical TCA cycle, rather than GABA shunt metabolism, to cope with salinity stress. HighlightBarley sustains respiration via the TCA cycle rather than activating the GABA shunt under salt stress, whereas in wheat, salt physiochemically inhibits TCA cycle function, and the GABA pathway is induced. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=152 SRC="FIGDIR/small/687118v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@16dcbe1org.highwire.dtl.DTLVardef@1644facorg.highwire.dtl.DTLVardef@aaa7f7org.highwire.dtl.DTLVardef@1f98912_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2025

Seeing through the Static: Reduced Imagery Vividness in Aphantasia is Associated with Impaired Temporal Lobe Signal Complexity

Aphantasia is the inability to experience mental imagery in full wakefulness without any prominent perceptual deficits. Visual aphantasia is associated with differences in distributed brain networks, but its neurobiological underpinnings remain a mystery. We rationalised that aphantasia may arise due to impairments in the top-down control over visual imagination. We expected that this in turn would prevent the brains of aphantasic subjects from differentiating neural activity encoding the contents of imagination from the background noise of resting activity, particularly within the ventral temporal lobes. To test this hypothesis, we re-analysed functional magnetic resonance imaging data collected from aphantasics (n = 23) and controls (n = 20) during a simple perception and imagery task. We used two measures of informational complexity to quantify the complexity of the spatial pattern of thresholded BOLD signal in the participants temporal lobes during visual imagery. This spatial complexity was lower in aphantasics than controls during blocks of imagery, but not during perception (P < 0.05). We then performed dynamic functional connectivity analyses on the same data to demonstrate that the higher-order networks of aphantasics coupled abnormally with the temporal lobes during imagery (P < 0.05). These results provide a novel perspective, reframing aphantasia as an inability of the visual system to selectively activate regions encoding object-specific visual categories above background levels of noise.

neuroscience↗

bioRxiv2023

Perception of butenolides by Bacillus subtilis via the α/β-hydrolase RsbQ

The regulation of behavioural and developmental decisions by small molecules is common to all domains of life. In plants, strigolactones and karrikins are butenolide growth regulators that influence several aspects of plant growth and development, as well as interactions with symbiotic fungi1-3. DWARF14 (D14) and KARRIKIN INSENSITIVE2 (KAI2) are homologous receptors that perceive strigolactones and karrikins, respectively, and that hydrolyse their ligands to effect signal transduction4-7. RsbQ, a homologue of D14 and KAI2 from the Gram-positive bacterium Bacillus subtilis, regulates growth responses to nutritional stress via the alternative transcription factor SigmaB ({sigma}B)8,9. However, the molecular function of RsbQ is unknown. Here we show that RsbQ perceives butenolide compounds that are bioactive in plants. RsbQ is thermally destabilised by the synthetic strigolactone GR24 and its desmethyl butenolide equivalent dGR24. We show that, like D14 and KAI2, RsbQ is a functional butenolide hydrolase that undergoes covalent modification of the catalytic histidine residue. Exogenous application of both GR24 and dGR24 inhibited the endogenous signalling function of RsbQ in vivo, with dGR24 being 10-fold more potent. Application of dGR24 to B. subtilis phenocopied loss-of-function rsbQ mutations and led to a significant down-regulation of {sigma}B-regulated transcripts. We also discovered that exogenous butenolides promoted the transition from planktonic to biofilm growth. Our results suggest that butenolides may serve as inter-kingdom signalling compounds between plants and bacteria to help shape rhizosphere communities.

microbiology↗

bioRxiv2023

Metabolic adaptations leading to lignification in wheat roots under salinity stress

Analysis of salinity tolerance processes in wheat has focused on salt exclusion from shoots while root phenotypes have received limited attention. Here we consider the varying phenotypic response of four bread wheat varieties that differ in their type and degree of salt tolerance and consider in detail their molecular responses to salinity and changes in root cell wall lignification. These varieties were Westonia introgressed with Nax1 and Nax2 root sodium transporters (HKT1;5-A) that reduce Na+ accumulation in leaves, as well as the tissue tolerant Portugese landrace Mocho de Espiga Branca that has a mutation in the homologous gene HKT1;5-D and has high Na+ concentration in leaves. These three varieties were compared with the more salt-sensitive cultivar Gladius. Through the use of root structural analysis, ion concentrations, as well as differential proteomics and targeted metabolomics we provide an integrated view of the wheat root response to salinity. We show different metabolic re-arrangements in energy conversion, primary metabolic machinery and phenylpropanoid pathway leading to monolignol production in a genotype and genotype by treatment dependent manner that alters the extent and localisation of root lignification which correlated with an improved capacity of wheat roots to cope better under salinity stress.

plant biology↗

bioRxiv2023

Mitochondrial Complex I activity is inhibited by changes in the abundance of phosphatidylinositol and phosphatidylserine in wheat plants exposed to high temperatures.

Identifying the molecular basis of thermotolerance in crops is becoming increasingly important with the changing climatic conditions that challenge future food security. Sustaining cellular energy production under heat stress is vital in maintaining an uninterrupted growth cycle, and thus the mitochondria is instrumental in facilitating the overall heat-tolerance of a crop plant. Using targeted mass spectrometry, the changes in abundance of the lipo-protein network in mitochondrial membranes following a short episode of extremely high temperature were analysed in two wheat cultivars of differing thermotolerance. The results indicated that membrane lipids remodel in favour of shorter fatty acyl tails, and an increase in the abundance of phosphatidylinositol, while specific to the heat-tolerant cultivar was an increase in the abundance of phosphatidylserine. The differences between the lipid profiles of the two cultivars is a likely explanation for the decrease in Complex I NADH dehydrogenase activity in the heat-sensitive cultivar. Further metabolite analysis by LC-MS revealed malate accumulation, indicating that the disruption in Complex I activity impacts the catabolism of reducing equivalents. The measured increase in the total amount of phosphatidylserine in the heat-tolerant cultivar suggests a potential role in conveying thermotolerance for this minor membrane constituent, and highlights that a focus on membrane lipid composition during thermal stress will be essential for the breeding of future heat tolerant crops. SummaryO_LIWe evaluated changes to the lipo-protein network of wheat mitochondria of differing heat tolerance in response to heat shock. C_LIO_LIUsing targeted mass spectrometry, candidate transitions were selected to quantify changes in membrane lipids and the embedded protein components of the electron transport chain, which play a vital role in maintaining respiration. C_LIO_LIA significant increase in phosphatidylserine was exclusive to the mitochondria of the heat-tolerant wheat cultivar. In the absence of this, the heat-sensitive cultivar displayed a reduced Complex I activity. C_LIO_LIThe minor membrane constituent phosphatidylserine plays a role in conveying thermotolerance, making this membrane lipid a focal point for the breeding of future heat tolerant crops. C_LI

plant biology↗

bioRxiv2021

Distinct changes in mature root and growing root tip proteomes underlie physiological responses of bread wheat to salinity stress

The impact of salinity on wheat plants is often studied by analysis of shoot responses, even though the main mechanism of tolerance is shoot Na+ exclusion. There is a need to understand the molecular responses of root tissues that directly experience rising NaCl concentrations. We have combined analysis of root growth, ion content and respiration with proteome responses in wheat root tip and mature root tissues under saline conditions. We find significant changes in translation and protein synthesis, energy metabolism and amino acid metabolism in a root tissue specific manner. Translation and protein synthesis related proteins showed significant decreases in abundance only in root tips, as did most of the glycolytic enzymes and selected TCA cycle enzymes and ATP synthase subunits. This selective root tip proteome response indicates protein synthesis capacity and energy production were impaired under salt stress, correlating with the anatomical response of roots and reduced root tip respiration rate. Wheat roots respond directly to soil salinity, therefore shoot responses such as reduction in shoot growth and photosynthetic capacity need to be considered in light of these effects.

plant biology↗