Distinct carbohydrate and lipid-based molecular patterns within lipopolysaccharides from Burkholderia cepacia contribute to defense-associated differential gene expression in Arabidopsis thaliana

Abstract

Lipopolysaccharides are structural components within the cell walls of Gram-negative bacteria. The LPSs as microbe-associated molecular pattern (MAMP) molecules can trigger defense-related responses involved in MAMP-triggered immunity and basal resistance in plants, presumably from an initial perception event. LPS from Burkholderia cepacia as well as two fragments, the glycolipid, lipid A and the polysaccharide (OPS-core) chain, were used to treat Arabidopsis thaliana seedlings to evaluate the eliciting activities of the individual LPS sub-domains by means of Annealing Control Primer-based Differential Display transcript profiling. Genes found to be up-regulated encode for proteins involved in signal perception and transduction, transcriptional regulation and defense – and stress responses. Furthermore, genes encoding proteins involved in chaperoning, secretion, protein–protein interactions and protein degradation were differentially expressed. It is concluded that intact LPS, as well as the two sub-components, induced the expression of a broad range of genes associated with perception and defense as well as metabolic reprogramming of cellular activities in support of immunity and basal resistance. Whilst the lipid A and OPS moieties were able to up-regulate sub-sets of defense-associated genes over the same spectrum of categories as intact LPS, the up-regulation observed with intact LPS was the more comprehensive, suggesting that the lipid A and glycan molecular patterns of the molecule act as partial agonists, but that the intact LPS structure is required for full agonist activity.