Oligogalacturonides are pectic fragments of the plant cell wall, whose signaling role has been described thus far during plant development and plant-pathogen interactions. In the present work, we evaluated the potential involvement of oligogalacturonides in the molecular communications between legumes and rhizobia during the establishment of nitrogen-fixing symbiosis. Oligogalacturonides with a degree of polymerization of 10 to 15 were found to trigger a rapid intracellular production of reactive oxygen species in Rhizobium leguminosarum bv. viciae 3841. Accumulation of H2O2, detected by both 2′,7′-dichlorodihydrofluorescein diacetate– based fluorescence and electron-dense deposits of cerium perhydroxides, was transient and did not affect bacterial cell viability, due to the prompt activation of the katG gene encoding a catalase. Calcium measurements carried out in R. leguminosarum transformed with the bioluminescent Ca2+ reporter aequorin demonstrated the induction of a rapid and remarkable intracellular Ca2+ increase in response to oligogalacturonides. When applied jointly with naringenin, oligogalacturonides effectively inhibited flavonoid-induced nod gene expression, indicating an antagonistic interplay between oligogalacturonides and inducing flavonoids in the early stages of plant root colonization. The above data suggest a novel role for oligogalacturonides as signaling molecules released in the rhizosphere in the initial rhizobium–legume interaction.

Oligogalacturonides: novel signalling molecules in Rhizobium-legume communications

MOSCATIELLO, ROBERTO;BALDAN, BARBARA;SQUARTINI, ANDREA;MARIANI, PAOLINA;NAVAZIO, LORELLA
2012

Abstract

Oligogalacturonides are pectic fragments of the plant cell wall, whose signaling role has been described thus far during plant development and plant-pathogen interactions. In the present work, we evaluated the potential involvement of oligogalacturonides in the molecular communications between legumes and rhizobia during the establishment of nitrogen-fixing symbiosis. Oligogalacturonides with a degree of polymerization of 10 to 15 were found to trigger a rapid intracellular production of reactive oxygen species in Rhizobium leguminosarum bv. viciae 3841. Accumulation of H2O2, detected by both 2′,7′-dichlorodihydrofluorescein diacetate– based fluorescence and electron-dense deposits of cerium perhydroxides, was transient and did not affect bacterial cell viability, due to the prompt activation of the katG gene encoding a catalase. Calcium measurements carried out in R. leguminosarum transformed with the bioluminescent Ca2+ reporter aequorin demonstrated the induction of a rapid and remarkable intracellular Ca2+ increase in response to oligogalacturonides. When applied jointly with naringenin, oligogalacturonides effectively inhibited flavonoid-induced nod gene expression, indicating an antagonistic interplay between oligogalacturonides and inducing flavonoids in the early stages of plant root colonization. The above data suggest a novel role for oligogalacturonides as signaling molecules released in the rhizosphere in the initial rhizobium–legume interaction.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2523995
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