An oxidative burst and its attenuation by bacterial peroxidase activity is required for optimal establishment of the Arachis hypogaea-Bradyrhizobium sp. symbiosis

MUÑOZ, VANINA; IBAÑEZ, FERNANDO; FIGUEREDO, MARÍA SOLEDAD; FABRA, ADRIANA

JOURNAL OF APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016

1364-5072

Aims: The main purpose of this study was to determine whether the Arachishypogaea L. root oxidative burst, produced at early stages of its symbioticinteraction with Bradyrhizobium sp. SEMIA 6144, and the bacterial antioxidantsystem are required for the successful development of this interaction.Methods and Results: Pharmacological approaches were used to reduce bothplant oxidative burst and bacterial peroxidase enzyme activity. In plants whoseH2O2 levels were decreased, a low nodule number, a reduction in theproportion of red nodules (%) and an increase in the bacteroid density werefound. The symbiotic phenotype of plants inoculated with a Bradyrhizobiumsp. SEMIA 6144 culture showing decreased peroxidase activity was alsoaffected, since the biomass production, nodule number and percentage of rednodules in these plants were lower than in plants inoculated withBradyrhizobium sp. control cultures.Conclusions: We demonstrated for the first time that the oxidative bursttriggered at the early events of the symbiotic interaction in peanut, is aprerequisite for the efficient development of root nodules, and that theantioxidant system of bradyrhizobial peanut symbionts, particularly the activityof peroxidases, is counteracting this oxidative burst for the successfulestablishment of the symbiosis.Significance and Impact of the Study: Our results provide new insights intothe mechanisms involved in the development of the symbiotic interactionestablished in A. hypogaea L. a legume infected in an intercellular way.