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Suppression of clubroot disease under neutral pH caused by inhibition of spore germination of Plasmodiophora brassicae in the rhizosphere

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Title: Suppression of clubroot disease under neutral pH caused by inhibition of spore germination of Plasmodiophora brassicae in the rhizosphere
Authors: Niwa, Reiko Browse this author
Nomura, Yoshinobu Browse this author
Osaki, Mitsuru Browse this author
Ezawa, Tatsuhiro Browse this author →KAKEN DB
Keywords: Brassica rapa
nuclear/cell-wall double staining
soil pH
soilborne disease
spore germination
Issue Date: Jun-2008
Publisher: British Society for Plant Pathology
Journal Title: Plant Pathology
Volume: 57
Issue: 3
Start Page: 445
End Page: 452
Publisher DOI: 10.1111/j.1365-3059.2007.01817.x
Abstract: To elucidate the mechanism of clubroot suppression under neutral soil pH, a highly reproducible germination assay system under soil culture conditions was designed based on the hypothesis that germinated spores of Plasmodiophora brassicae could be identified by the absence of a nucleus (i.e. having released a zoospore to infect a root hair of the host plant). Brassica rapa var. perviridis seedlings were inoculated with a spore suspension of P. brassicae at a rate of 2.0 ×106 spores g-1 soil and grown in a growth chamber for 7 days. The spores were recovered from rhizosphere and non-rhizosphere soils and stained with both Fluorescent Brightener 28 (cell-wall-specific) and SYTO 82 orange fluorescent nucleic-acid stain (nucleus-specific stain). Total numbers of spores were counted under UV-excitation, and spores with a nucleus that fluoresced orange under G-excitation were counted. The significant increase in the percentage of spores without a nucleus (germinated spores) in the rhizosphere after 7 days’ cultivation and the correlation with root-hair infections validated the assay system. Applications of calcium-rich compost or calcium carbonate to neutralize the soil significantly reduced the percentage of germinated spores in the rhizosphere, as well as the number of root-hair infections. The present study provides direct evidence that the inhibition of spore germination is the primary cause of disease suppression under neutral soil pH.
Rights: The definitive version is available at
Type: article (author version)
Appears in Collections:農学院・農学研究院 (Graduate School of Agriculture / Faculty of Agriculture) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 江澤 辰広

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