Effect of long-term vineyard monoculture on rhizosphere populations of pseudomonads carrying the antimicrobial biosynthetic genes phlD and/or hcnAB |
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Authors: | Miroslav Svercel,Danilo Christen,Yvan Moë nne-Loccoz,Brion Duffy,& Geneviè ve Dé fago |
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Affiliation: | Plant Pathology, Institute of Integrative Biology, Zürich, Switzerland;;Universitéde Lyon, Lyon, France;;UniversitéLyon 1, Villeurbanne, France;;CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France;and;Agroscope Changins-Wädenswil, Swiss Federal Research Station for Horticulture, Plant Protection Division, Wädenswil, Switzerland |
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Abstract: | The impact of repeated culture of perennial plants (i.e. in long-term monoculture) on the ecology of plant-beneficial bacteria is unknown. Here, the influence of extremely long-term monocultures of grapevine (up to 1603 years) on rhizosphere populations of fluorescent pseudomonads carrying the biosynthetic genes phlD for 2,4-diacetylphloroglucinol and/or hcnAB for hydrogen cyanide was determined. Soils from long-term and adjacent short-term monoculture vineyards (or brushland) in four regions of Switzerland were baited with grapevine or tobacco plantlets, and rhizosphere pseudomonads were studied by most probable number (MPN)-PCR. Higher numbers and percentages of phlD + and of hcnAB + rhizosphere pseudomonads were detected on using soil from long-term vineyards. On focusing on phlD , restriction fragment length polymorphism profiling of the last phlD -positive MPN wells revealed seven phlD alleles (three exclusively on tobacco, thereof two new ones). Higher numbers of phlD alleles coincided with a lower prevalence of the allele displayed by the well-studied biocontrol strain Pseudomonas fluorescens F113. The prevalence of this allele was 35% for tobacco in long-term monoculture soils vs. >60% in the other three cases. We conclude that soils from long-term grapevine monocultures represent an untapped resource for isolating novel biocontrol Pseudomonas strains when tobacco is used as bait. |
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Keywords: | biological control monoculture Vitis Pseudomonas hydrogen cyanide 2,4-diacetylphloroglucinol |
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