Affiliation:
1. Institute of Integrative Biology, Plant Pathology, Swiss Federal Institute of Technology, CH-8092 Zurich, Switzerland
2. Institute of Natural Resource Sciences, Zurich University of Applied Sciences, CH-8820 Wädenswil, Switzerland
3. Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
Abstract
ABSTRACT
There is a significant potential to improve the plant-beneficial effects of root-colonizing pseudomonads by breeding wheat genotypes with a greater capacity to sustain interactions with these bacteria. However, the interaction between pseudomonads and crop plants at the cultivar level, as well as the conditions which favor the accumulation of beneficial microorganisms in the wheat rhizosphere, is largely unknown. Therefore, we characterized the three Swiss winter wheat (
Triticum aestivum
) cultivars Arina, Zinal, and Cimetta for their ability to accumulate naturally occurring plant-beneficial pseudomonads in the rhizosphere. Cultivar performance was measured also by the ability to select for specific genotypes of 2,4-diacetylphloroglucinol (DAPG) producers in two different soils. Cultivar-specific differences were found; however, these were strongly influenced by the soil type. Denaturing gradient gel electrophoresis (DGGE) analysis of fragments of the DAPG biosynthetic gene
phlD
amplified from natural
Pseudomonas
rhizosphere populations revealed that
phlD
diversity substantially varied between the two soils and that there was a cultivar-specific accumulation of certain
phlD
genotypes in one soil but not in the other. Furthermore, the three cultivars were tested for their ability to benefit from
Pseudomonas
inoculants. Interestingly, Arina, which was best protected against
Pythium ultimum
infection by inoculation with
Pseudomonas fluorescens
biocontrol strain CHA0, was the cultivar which profited the least from the bacterial inoculant in terms of plant growth promotion in the absence of the pathogen. Knowledge gained of the interactions between wheat cultivars, beneficial pseudomonads, and soil types allows us to optimize cultivar-soil combinations for the promotion of growth through beneficial pseudomonads. Additionally, this information can be implemented by breeders into a new and unique breeding strategy for low-input and organic conditions.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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