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The microbiome of soils suppressive to Spongospora diseases of potato

Richard Falloon: The New Zealand Institute for Plant & Food Research Limited

<div>The plasmodiophorid <em>Spongospora subterranea</em> causes root galling and tuber powdery scab on potato plants, yet these diseases did not develop in potato crops grown successively over 10 years in a long-term crop rotation field trial, indicating that the soil was naturally suppressive to this pathogen. A subsequent project is determining the characteristics of 12 vegetable-growing soils (including the trial soil), selected to represent different geographic regions, cropping histories and soil types, for their suppression of <em>Spongospora</em> diseases. As part of the study, total DNA was extracted from subsamples of each soil. The microbial communities are being characterized, using generic primers targeting variable regions in the 16S rRNA gene for bacteria or the rRNA internal transcribed spacer region for fungi. The amplicons are being sequenced using the Illumina MiSeq system. The sequence data will be classified into operational taxonomic units to generate the microbial community profile for each soil. Diversity and network analyses will be used to determine patterns and associations in the sequence dataset. This project also includes detailed determination of the physical and chemical characteristics of the 12 field soils, and aims to describe soil biotic and abiotic factors associated with suppression of <em>S. subterranea</em>. The goal is to identify soil factors that may be manipulated as part of integrated management of the economically important yield- and quality-limiting diseases of potato caused by <em>S. subterranea</em>.</div>