Biocontrol of black scurf on potato by seed tuber treatment with Pythium oligandrum

Sachiko Ikeda, Ayano Shimizu, Motoshige Shimizu, Hideki Takahashi, Shigehito Takenaka

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The biological control activity of Pythium oligandrum against black scurf of potato caused by Rhizoctonia solani AG-3 was evaluated in field experiments after treatment of potato seed tubers with P. oligandrum. Seed tubers infected with black scurf sclerotia were dipped for a few seconds in a suspension of 10 3, 10 4 or 10 5mL -1 P. oligandrum oospores and were then air-dried. Each level of P. oligandrum-treatment significantly reduced the disease rates of stolon at a level similar to that achieved by chemical control. When P. oligandrum populations adherent to the surface of seed tubers were determined, oospore counts on tubers treated with 10 4 or 10 5oosporesmL -1 were about 540/cm 2 or about 22,000/cm 2 just after dipping and decreased to about 170/cm 2 or 2900/cm 2 after a 3-week incubation, respectively. Confocal laser scanning microscopic observation with an immuno-enzymatic staining procedure showed that P. oligandrum hyphae had colonized the sclerotia and established close contact by coiling around the R. solani hyphae present on the surface of seed tubers, in a manner similar to that observed in the dual-culture test. Quantification of R. solani DNA by PCR indicated that the R. solani population was reduced on the seed tubers treated with P. oligandrum compared to untreated tubers. Furthermore, the ability of P. oligandrum to induce resistance against black scurf was determined using a potato tuber disk assay. Treatment of tuber disks with the cell wall protein fraction of P. oligandrum enhanced the expression of defense-related genes such as 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase, lipoxygenase and basic PR-6 genes, and reduced disease severity upon challenge with R. solani compared with untreated controls. These results suggest that biocontrol mechanisms employed by P. oligandrum against black scurf involve both mycoparasitism and induced resistance.

Original languageEnglish
Pages (from-to)297-304
Number of pages8
JournalBiological Control
Volume60
Issue number3
DOIs
Publication statusPublished - 2012 Mar 1

Keywords

  • Biological control
  • Black scurf
  • Colonization
  • Induced resistance
  • Mycoparasitism
  • Pythium oligandrum

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Insect Science

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