Molecular characterization and pathogenicity of Pythium species associated with damping-off in greenhouse cucumber (Cucumis sativus) in Oman

A. M. Al-Sa'di, A. Drenth, M. L. Deadman, A. W A M De Cock, E. A B Aitken

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

A study was undertaken in 2004 and 2005 to characterize pathogens associated with damping-off of greenhouse-grown cucumber seedlings in 13 districts in Oman. Identification of Pythium to the species level was based on sequences of the internal transcribed spacer (ITS) of the ribosomal DNA. Of the 98 Pythium isolates collected during the survey, Pythium aphanidermatum, P. spinosum, P. splendens and P. oligandrum accounted for 76%, 22%, 1% and 1%, respectively. Pythium aphanidermatum was isolated from all of the districts, while P. spinosum was isolated from seven districts. Pathogenicity tests showed inter- and intraspecific variation in aggressiveness between Pythium species. Pythium aphanidermatum, P. spinosum and P. splendens were found to be highly aggressive at 25°C. However, the aggressiveness of P. spinosum decreased when the temperature was raised to 30°C, which was found to correspond to the lower frequency of isolation of P. spinosum in the warmer seasons, compared to the cooler time of the year. Pythium aphanidermatum exhibited limited intraspecific variation in the sequences of the ITS region of the rDNA and showed 100% similarity to the corresponding P. aphanidermatum sequences from GenBank. The ITS sequence data, as well as morphological characteristics of P. spinosum isolates, showed a high level of similarity within and between P. spinosum and P. kunmingense, and suggested that the two species were synonymous. This study represents the first report of P. spinosum, P. splendens and P. oligandrum in Oman.

Original languageEnglish
Pages (from-to)140-149
Number of pages10
JournalPlant Pathology
Volume56
Issue number1
DOIs
Publication statusPublished - Feb 2007

Keywords

  • Cucumber seedlings
  • Inter- and intraspecific variation
  • Pythium aphanidermatum
  • Pythium oligandrum
  • Pythium spinosum
  • Pythium splendens

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science

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