Adaptive defence-related changes in the metabolome of Sorghum bicolor cells in response to lipopolysaccharides of the pathogen Burkholderia andropogonis

Abstract

plant cell suspension culture systems are valuable for the study of complex biological systems such as inducible defence responses and aspects of plant innate immunity. perturbations to the cellular metabolome can be investigated using metabolomic approaches in order to reveal the underlying metabolic mechanism of cellular responses. Lipopolysaccharides from the sorghum pathogen, Burkholderia andropogonis (LpS B.a.), were purified, chemically characterised and structurally elucidated. The lipid A moiety consists of tetra-and penta-acylated 1,4'-bis-phosphorylated disaccharide backbone decorated by aminoarabinose residues, while the o-polysaccharide chain consists of linear trisaccharide repeating units of [→2)-α-Rha3CMe-(1 → 3)-α-Rha-(1 → 3)-α-Rha-(1 → ]. The effect of LPS B.a. in triggering metabolic reprogramming in Sorghum bicolor cells were investigated using untargeted metabolomics with liquid chromatography coupled to mass spectrometry detection. cells were treated with LpS B.a. and the metabolic changes monitored over a 30 h time period. Alterations in the levels of phytohormones (jasmonates, zeatins, traumatic-, azelaic-and abscisic acid), which marked the onset of defence responses and accumulation of defence-related metabolites, were observed. phenylpropanoids and indole alkaloids as well as oxylipins that included di-and trihydroxyoctadecedienoic acids were identified as signatory biomarkers, with marked secretion into the extracellular milieu. The study demonstrated that sorghum cells recognise LpS B.a. as a 'microbe-associated molecular pattern', perturbing normal cellular homeostasis. the molecular features of the altered metabolome were associated with phytohormone-responsive metabolomic reconfiguration of primary and secondary metabolites originating from various metabolic pathways, in support of defence and immunity. Plants are continuously exposed to an array of pathogens which can either be host-specific or can affect a wide range of hosts. Existing crop protection strategies are vulnerable against novel pathogens or pathogens developing increasing resistance against chemical controls 1. One of the major diseases affecting Sorghum bicolor, an economically important grain crop, is bacterial leaf stripe disease caused by Burkholderia andropogonis. Recent metabolomics insights revealed aspects of the molecular mechanisms of the S. bicolor-B. andropogonis pathophysiological interaction 2. The results revealed a dynamic and intricate network of the sorghum defence resources towards B. andropogonis in launching a heightened defensive capability for disease suppression 2. Plants employ several layers of defence to counter potential pathogens 3,4. These passive (preformed) and active (induced) responses are triggered upon detection of conserved immunogenic motifs, epitopes or 'patterns' such

Physcomitrium patens Infection by Colletotrichum gloeosporioides: Understanding the Fungal–Bryophyte Interaction by Microscopy, Phenomics and RNA Sequencing

“…Jasmonates and OPDA also induce the expression of pal in moss plants [ 54 ]. The major role of hormones in biotic stress caused by pathogens has been documented extensively in vascular plants, such as for sorghum ( Sorghum bicolor L.), potato ( Solanum tuberosum L.) and wheat ( T. aestivum L.), where the accumulation of salicylic acid resulted in greater expression of plant defense genes [ 55 , 56 , 57 ]. In vascular plants, salicylic acid mainly activates the defense responses against biotrophic pathogens, while jasmonic acid and ethylene induce defense responses against necrotrophic pathogens [ 58 ].…”

Changes and composition of microbial community during aerobic composting of household food waste

“…The relative abundance of Proteobacteria in the two groups of samples in stage1both exceeded 90%, indicating that Proteobacteria is in an absolutely dominant position in both A1 and C1. Many bacteria of Proteobacteria are pathogenic (23),such as Cronobacter (24), Burkholderia (25,26) and Ochrobactrum (27). The main bacteria phyla in stage2 is: A2: Firmicutes (96.23%), Proteobacteria (3.07%); C2: Firmicutes (96.60%), Proteobacteria (2.62%).…”

Lipopolysaccharides trigger synthesis of the allelochemical sorgoleone in cell cultures of Sorghum bicolor

“…Cell suspension cultures of Sorghum bicolor ('Sweet White' cultivated variety) (Agricol, Pretoria, South Africa) were cultured as previously described. 14 Purified lipopolysaccharides (LPS)(100 µg mL −1 ) from B. andropogonis, 8 was used in the elicitation of the cell suspensions. Following inoculation, the cultures were incubated on an orbital shaker at 130 rpm and 25°C.…”

“…These were snap frozen with liquid nitrogen and stored at -80° C until both intracellular and extracellular metabolite extraction steps could be performed. 8 The experimental design included three independent biological repeats and three technical repeats of each extract (n = 9).…”