Role of bacterial quorum sensing compounds of the N-Acyl-Homoserine Lactone type (AHL) in improving resistance towards plant pathogens and increasing tolerance to salt and drought stresses

Role of bacterial quorum sensing compounds of the N-Acyl-Homoserine Lactone type (AHL) in improving resistance towards plant pathogens and increasing tolerance to salt and drought stresses

3^rd Annual Congress on Plant Biology & Agricultural Sciences
April 04, 2022 | Webinar

Anton Hartmann

Ludwig-Maximilian- University Munich, Germany

Abstract:

Communication between microbes and plant host is of utmost importance for plant’s health. Bacterial quorum-sensing compounds of the N-Acyl- Homoserine Lactone (AHL) type were demonstrated to enhance resistance towards pathogens and tolerance to abiotic stress factors in diverse crop plants.In quorum sensing regulation, small molecular signals are produced and released into the environment. The signals also diffuse back in the cells and the resulting signal concentration, which is dependent on the bacterial density and habitat conditions, is sensed by an intracellular receptor. At concentrations above a certain concentration (quorum), the signal production itself (auto-induction) is enhanced and a whole regulon on QS-regulated genes are newly expressed. In Gram-negative bacteria, the major auto-inducer compounds are of the N-Acyl Homoserine Lactone type (AHL). QS-signals can also interact in an inter-kingdom manner with eucaryotes, e.g. plants.AHLs can be divided into two groups: hydrophilic AHLs, with short acyl chains (C4-C8) are taken up by roots in an ATPdriven transport. This was demonstrated for barley with 3 H-radiolabeled AHL, high resolving metabolite analysis and AHL-antibody tests. Additionally, C6- and C8-HSL stimulate growth of roots, as shown in Arabidopsis affecting the hormonal status of the plant. In tomato, C6-, C8- and C10-HSLs conferred resistance to Alternaria alternata. AHLs with long chains (C12 or C14) are not transported to the shoots. A signal chain into the shoot is activated resulting in enhanced resistance to several biotrophic,and hemibiotrophic pathogens. It was shown that AHL-priming for enhanced resistance depends on salicylic acid and oxylipin signalling. These interactions occurred when AHL-producing bacteria were inoculated on roots, while mutants or transconjugants devoid of AHLs failed to induce AHL-priming. Furthermore, AHLs and AHL-producing bacteria are involved in improved tolerance to salt and drought stresses, as was shown for rice, Arabidopsis and wheat. These beneficial activities of AHLs could be applied in agriculture. responses and improvements in gaining resistance towards plant pathogens.

Biography:

Prof. Dr. Anton Hartmann studied biochemistry (dipl. biochem.) at University of Tuebingen, Germany, and got his doctoral degree at the Institute of Microbiology in 1979. He was assistant professor at University of Bayreuth, Germany, than postdoc at the Department of Biochemistry at University of Wisconsin, Madison, USA, in Prof. R.H. Burris‘ laboratory from 1983-1985. Back at University of Bayreuth, he joined the microbial department and got the university teaching degree (habilitation) in 1989. The same year he joined Helmholtz Zentrum Munich, Institute of Soil Ecology, where he was deputy director and leader of the research group „Molecular microbial ecology of rhizosphere bacteria“. Since 1990 he was teaching Soil Microbiology and Microbe-Plant-Interactions at Ludwig-Maximilian-University Munich. In 2007 he became head Research Unit „Microbe-Host Interactions“ at Helmholtz Zentrum Munich. Dr. Hartmann´s research applied since 30 years molecular microbial ecology approaches, focusing on biological nitrogen fixation of rhizosphere bacteria and quorum sensing of plant-associated beneficial bacteria. He published 190 scientific publications and 60 book chapters; his RG-score is 43.78. Prof. Hartmann retired in 2015 from Helmholtz Zentrum Munich and is still active as emerit. Professor of LMU Munich.

PDF HTML