Rhizospheric events in the infection process of Acacia mangium by Bradyrhizobium spp.

Prin Yves, Galiana Antoine, Duhoux Emile, Reddell Paul. 1997. Rhizospheric events in the infection process of Acacia mangium by Bradyrhizobium spp.. In : Colloque Rhizosphère Aix'97, Aix en Provence, 26-27 novembre 1997. Société française de microbiologie. s.l. : s.n., 1 p. Colloque Rhizosphère Aix'97, Aix-en-Provence, France, 26 November 1997/27 November 1997.

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Abstract : Acacia mangium is a legume tree used in industrial plantations for the production of pulp wood, and for the rehabilitation of degraded soils. Its ability to grow in very poor soils is due to a symbiotic association with nitrogen-fixing Bradyrhizobium. In this study we described the early events leading to the infection of the root and the formation of the nitrogen-fixing nodule. 1 day-old seedlings were inoculated by imersion in a 4 day-old culture of Bradyrhizobium strain Aust13c for 10 min and then transferred to 25 x 250 mm growth tubes. Observations were made 3, 6 9 and 12 days after inoculation by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and light microscopy. The first visible interaction is an intense bacterial proliferation in the mucilage layer covering rhizodermis from the root cap to the root hair zone. Images of mucilage lysis are frequently observed around the bacterial cells through SEM and TEM. Root hairs are short and very sparse. They often are located dose to the emergence point of lateral roots. As nodulation often occurs close to emergence sites of lateral roots, the question was raised of the mode of penetration of the bacteria in the root: (i) through the deformation of a root hair or (ii) via the "crack entry" way at a lateral root emergence. Serial sections through young nodules allowed to evidence that the classical infection through a deformed root hair with numerous infection threads is the usual way of infection. (Texte intégral)

Classification Agris : P34 - Soil biology

Auteurs et affiliations

  • Galiana Antoine, CIRAD-FORET-PLANTATIONS FORESTIERES (MYS) ORCID: 0000-0002-5293-5049
  • Duhoux Emile, ORSTOM [Institut français de recherche scientifique pour le développement en coopération] (FRA)
  • Reddell Paul, CSIRO (AUS)

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