title: Stimulation of defense reactions in Medicago truncatula by antagonistic lipopeptides from Paenibacillus sp. strain B2.
abstract: With the aim of obtaining new strategies to control plant diseases, we investigated the ability of antagonistic lipopolypeptides (paenimyxin) from Paenibacillus sp. strain B2 to elicit hydrogen peroxide (H₂O₂) production and several defense-related genes in the model legume Medicago truncatula. For this purpose, M. truncatula cell suspensions were used and a pathosystem between M. truncatula and Fusarium acuminatum was established. In M. truncatula cell cultures, the induction of H₂O₂ reached a maximum 20 min after elicitation with paenimyxin, whereas concentrations higher than 20 μM inhibited H₂O₂ induction and this was correlated with a lethal effect. In plant roots incubated with different concentrations of paenimyxin for 24 h before inoculation with F. acuminatum, paenimyxin at a low concentration (ca. 1 μM) had a protective effect and suppressed 95% of the necrotic symptoms, whereas a concentration higher than 10 μM had an inhibitory effect on plant growth. Gene responses were quantified in M. truncatula by semiquantitative reverse transcription-PCR (RT-PCR). Genes involved in the biosynthesis of phytoalexins (phenylalanine ammonia-lyase, chalcone synthase, chalcone reductase), antifungal activity (pathogenesis-related proteins, chitinase), or cell wall (invertase) were highly upregulated in roots or cells after paenimyxin treatment. The mechanisms potentially involved in plant protection are discussed.
authors.affiliation: UMR INRA 1088, CNRS 5184, Université de Bourgogne Plante-Microbe-Environnement CMSE-INRA, 17 Rue Sully, BP 86510, 21065 Dijon Cedex, France.
authors.forename: Sameh
authors.initials: S
authors.lastname: Selim
authors.forename: Jonathan
authors.initials: J
authors.lastname: Negrel
authors.forename: David
authors.initials: D
authors.lastname: Wendehenne
authors.forename: Sergio
authors.initials: S
authors.lastname: Ochatt
authors.forename: Silvio
authors.initials: S
authors.lastname: Gianinazzi
authors.forename: Diederik
authors.initials: D
authors.lastname: van Tuinen
mesh_terms: D018929:Cell Culture Techniques; D018920:Coculture Techniques; D005670:Fusarium / Q000254:growth & development / Q000472:pathogenicity; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism; D055666:Lipopeptides / Q000276:immunology* / Q000302:isolation & purification*; D046913:Medicago truncatula / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D056507:Paenibacillus / Q000737:chemistry* / Q000276:immunology*; D018517:Plant Roots / Q000382:microbiology
chemical_list: D055666:Lipopeptides; D006861:Hydrogen Peroxide