Role of bacterial rhamnolipids in plant tolerance to abiotic stresses

by Maoulida Ali Bouchrati
Doctoral thesis
Date of Examination:2024-11-05
Date of issue:2025-10-29
Advisor:Prof. Dr. Ivo Feussner
Referee:Prof. Dr. Till Ischebeck
Referee:Prof. Dr. Marie-Laure Fauconnier
Persistent Address: http://dx.doi.org/10.53846/goediss-11352

 

 

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Abstract

English

Rhamnolipids (RLs), glycolipids produced by Pseudomonas and Burkholderia species, have been described as potential biocontrol agents due to their antagonistic activity against pathogens and their ability to induce plant defence responses. To date, however, certain aspects of RLs remain to be elucidated, notably their effects under abiotic stress and their mechanism of perception by the plasma membrane (PM). Previous results have suggested that the perception of RLs involves an interaction with PM lipids. In this thesis, we showed that RLs do not protect Arabidopsis against heat stress. Lipidomic analyses revealed that the application of RLs do not induce any major change in the composition of in vivo PM lipids. In addition, we showed that the effectiveness of RLs in inducing resistance to Pseudomonas syringae is compromised in the longevity assurance gene (lag) one homologous gene 2 (loh2) mutant, a ceramide synthetase knockout mutant. Lipidomic analysis showed that loh2 had an altered SL composition, but that its phospholipid and sterol composition was similar to that of Wt. Proteomic analysis revealed that the loss of LOH2 had no major impact on the composition of the Arabidopsis PM proteome. Taken together, these data indicate that the reduction in RL efficiency in the loh2 mutant is not due to changes in PM lipid composition, but rather to a potential influence of membrane lipids on signalling processes.
Keywords: Rhamnolipids; Lipidomic; Arabidopsis thaliana; Plasma membrane; Plant immunity; Photosynthesis
 
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