Table 1. Prominent examples of functions of the different LPS domains in mammalian and plant immunity^*.

	Mammals	Plants
OPS	Strongly antigenic in adaptive immunity; classification of bacterial strains according to serotypes [2,36]. Important for survival within the host and virulence [2,3,21].	Synthetic oligo-rhamnans (50–100 μg/ml) and Burkholderia OPS (50–100 μg/ml) induce defense gene expression in Arabidopsis [24,28]. Important for survival in plant tissue and virulence [4,29].
Core region	P. aeruginosa LPS is specifically internalized through its outer core oligosaccharide by cystic fibrosis transmembrane conductance regulator [39].	Xanthomonas core oligosaccharides (20–50 μg/ml) induce defense responses in Arabidopsis and tobacco [25,26,29].
LA	Typical enterobacterial LA is sensed as PAMP via TLR4/MD-2, CD14, and non-canonical inflammatory caspases and triggers inflammation [14,17,19]. Other LA structures (depending on the acylation and phosphorylation pattern and other modifications) are only weak agonists or even antagonists of TLR4/MD-2 signaling [3,17,20,33].	Pseudomonas/Xanthomonas LPS/LA (0.5–25 μg/ml) is sensed as PAMP via LORE in cruciferous plants and induces pattern-triggered immunity (PTI) [30]. LPS/LA (20–100 μg/ml) from diverse bacterial species (including Pseudomonas, Xanthomonas, E. coli and Burkholderia cepacia) induce defense responses in Arabidopsis, tobacco, and rice [22,23,26–29,31]. By contrast, [25] do not observe defense responses to Xanthomonas LA in tobacco.

*A comprehensive literature overview about plant LPS responses is available in [4,29]