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Poster De Conférence Année : 2019

Are culturable Phosphate Solubilizing Bacteria diversity and efficiency shaped by plant cover requirements?

Résumé

Plants, mainly through their root exudates, are a major key modelling structure and diversity of rhizospheric soil microbial community[2]. Thus selected beneficial microorganisms could sustain plant growth through important functions involved in biocontrol or nutrition[3]. Some of them are described as Phosphate Solubilizing Bacteria (PSB) and can make available the insoluble P in soil solution for the plant[4]. They could represent an alternative to inputs of mineral P fertilizers. In this context we hypothesised that plant cover could exert a selective pressure on PSB community leading to differences in diversity and main characteristics of PSB species, principally their efficiency in P solubilisation, corresponding to plant specific requirements. A PSB screening experiment was carried out from soil of two different plots. The first plot presented 2 distinct juxtaposed plant covers: Rapeseed and Winter Pea (Pisum sativum). The second plot was a Faba Bean (Vicia faba) culture. Each isolated strain was screened on two specific growth media with contrasting N:P ratios (NBRIP and Pikovskaya medium). Other metabolic functions of interest for these PSB strains were tested such as auxin and siderophore production. A total of 166 strains were identified as potential PSB. Based on their P solubilization index, no P solubilisation efficiency differences have been observed between plant covers on NBRIP medium (N:P ratio : 0.09). However, on Pikovskaya medium (N:P ratio : 0.7), the efficiency of strains was significantly higher for those isolated under Rapeseed (P solubilization index average: 1.61) while those for strains isolated from the 2 legume covers were similar but lower (1.34, 1.36 respectively for Winter bean, on the same field than rapeseed, and Faba bean). These differences could be related to lower P requirement for Winter Pea and Faba Bean. The same response pattern was observed for genus repartition after 16S ADNr sequencing with higher diversity observed under rapeseed cover. Major PSB genus identified are Bacillus and Pseudomonas. Among the 166 strains, 54 produce auxin and could be considered as potential Plant Growth Promoting Bacteria. Approximately 25% of those strains produce siderophore and could solubilize several complexed-P forms. These results suggest that observed efficiency of a non-negligible part of PSB community is directly shaped by plant selection of its microbiome according to crop P requirements but also to soil availability in other nutrients, such as N.
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Dates et versions

hal-04374438 , version 1 (05-01-2024)

Identifiants

  • HAL Id : hal-04374438 , version 1

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Charlotte Amy, Mélanie Bressan, Karine Laval, Jean-Christophe Avice. Are culturable Phosphate Solubilizing Bacteria diversity and efficiency shaped by plant cover requirements?. Journée Scientifique de la Fédération de la Recherche NORVEGE, May 2019, Mont-Saint-Aignan, France. ⟨hal-04374438⟩
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