Biology subjects

Taylor, N. L.

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

4 recordsLinked to original sources

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↗