N‐acyl‐homoserine lactone uptake and systemic transport in barley rest upon active parts of the plant

Abstract

SummaryBacteria communicate with each other in a population density-dependent process known as quorum sensing. N-acyl-homoserine lactones (HSLs) are the autoinducers of Gram-negative bacteria and the best-studied quorum sensing signals so far. HSLs induce various responses in plants, including systemic resistance and root development.Here, we used different methods, including tritium labelling, sensor strain assays and monoclonal antibodies (mAbs), to analyse the uptake and translocation of C8-and C10-homoserine lactones into barley (Hordeum vulgare cv Barke).Both HSLs were already systemically transported into the shoot at 2 h after application. HSL uptake could be inhibited by orthovanadate, demonstrating that ABC transporters are involved in the uptake. Root transport occurs predominantly via the central cylinder, which was shown by transport inhibition via KCl application and autoradiography of root cross-sections. Furthermore, a newly established detection method with mAbs allowed the first detection of a systemic transport of long-chain HSLs in plants.The coupled use of different HSL detection methods demonstrated that the uptake and transport of HSLs into barley does not occur passively, but relies, at least partially, on active processes in the plant.

Effect of quorum sensing signals produced by seaweed-associated bacteria on carpospore liberation from Gracilaria dura

“…A similar finding was also observed in the higher plants. It has been reported that short side-chain AHL compounds are easily soluble in water and are actively taken up into plant roots as well as transported through shoots, as compared to long acyl side chain AHLs in barley and A. thaliana (Götz et al, 2007; von Rad et al, 2008; Hartmann et al, 2014; Sieper et al, 2014). …”

Bacterial quorum sensing compounds are important modulators of microbe-plant interactions

“…Furthermore, it was shown, that better water soluble short side chain AHL-compounds are actively taken up into plant roots and transported along the roots into the shoot; in contrast, the lipophilic long acyl side chain AHLs are not transported in barley and A. thaliana . (Götz et al, 2007; von Rad et al, 2008; Sieper et al, 2014). However, no uptake was detected in the legume yam bean ( Pachyrhizus erosus (L.) Urban) (Götz et al, 2007).…”

“…The latter finding corroborates the report of Delalande et al (2005) that legumes like Lotus corniculatus produce lactonases which degrade AHLs and prevent their uptake and transport. In barley, it could further be demonstrated that C8- and C10-AHLs are taken up in a cell energy dependent manner by ABC-transporters into the root and transported via the central cylinder into the shoot (Sieper et al, 2014). …”

N-Acyl-Homoserine Lactone Primes Plants for Cell Wall Reinforcement and Induces Resistance to Bacterial Pathogens via the Salicylic Acid/Oxylipin Pathway

“…A recent uptake and transport study of radioactive C8-HSL and C10-HSL showed that the intermediate-length lipid chain AHLs are taken up and transported into the lower shoot zone, although not into the upper leaf tissues of barley plants (Sieper et al, 2013). Therefore, a likely explanation of oxo-C14-HSL-induced resistance in distal tissue is a systemic induced resistance.…”