Bacteria of the genus Rhodopseudomonas (Bradyrhizobiaceae): Obligate symbionts in mycelial cultures of the black truffles Tuber melanosporum and Tuber brumale

Le Roux Christine, Tournier Estelle, Lies Adrien, Sanguin Hervé, Chevalier Gérard, Duponnois Robin, Mousain Daniel, Prin Yves. 2016. Bacteria of the genus Rhodopseudomonas (Bradyrhizobiaceae): Obligate symbionts in mycelial cultures of the black truffles Tuber melanosporum and Tuber brumale. SpringerPlus, 5 (1085), 10 p.

Quartile : Q2, Sujet : MULTIDISCIPLINARY SCIENCES

Résumé : Background: This work aimed at characterizing 12 isolates of the genus Tuber including Tuber melanosporum (11 isolates) and Tuber brumale (one isolate). This was done using internal transcribed spacer (ITS) sequences, confirming their origin. Results: Analysis of their mating type revealed that both MAT1-1 and MAT1-2 exist within these isolates (with 3 and 8 of each, respectively). We observed that each of these cultures was consistently associated with one bacterium that was intimately linked to fungal growth. These bacterial associates failed to grow in the absence of fungus. We extracted DNA from bacterial colonies in the margin of mycelium and sequenced a nearly complete 16S rDNA gene and a partial ITS fragment. We found they all belonged to the genus Rhodopseudomonas, fitting within different phylogenetic clusters. No relationships were evidenced between bacterial and fungal strains or mating types. Rhodopseudomonas being a sister genus to Bradyrhizobium, we tested the nodulation ability of these bacteria on a promiscuously nodulating legume (Acacia mangium), without success. We failed to identify any nifH genes among these isolates, using two different sets of primers. Conclusions: While the mechanisms of interaction between Tuber and Rhodopseudomonas remain to be elucidated, their interdependency for in vitro growth seems a novel feature of this fungus.

Mots-clés Agrovoc : Tuber melanosporum, Rhodopseudomonas, Tuber brumale, Acacia mangium, tubercule, Fixation de l'azote

Mots-clés libres : Tuber, Bacteria, Rhodopseudomonas

Classification Agris : P34 - Biologie du sol

Champ stratégique Cirad : Axe 1 (2014-2018) - Agriculture écologiquement intensive

Auteurs et affiliations

• Le Roux Christine, CIRAD-BIOS-UMR LSTM (FRA) ORCID: 0000-0003-0668-3589
• Tournier Estelle, CIRAD-BIOS-UMR LSTM (FRA)
• Lies Adrien, UM2 (FRA)
• Sanguin Hervé, CIRAD-BIOS-UMR LSTM (FRA)
• Chevalier Gérard, INRA (FRA)
• Duponnois Robin, IRD (FRA)
• Mousain Daniel, Société d'Horticulture et d'Histoire Naturelle de l'Hérault (FRA)
• Prin Yves, CIRAD-BIOS-UMR LSTM (FRA) ORCID: 0000-0002-3706-0045

Source : Cirad-Agritrop (https://agritrop.cirad.fr/581068/)

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