Genetic diversity, aggressiveness and metalaxyl sensitivity of Pythium aphanidermatum populations infecting cucumber in Oman

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

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Seventy three isolates of Pythium aphanidermatum obtained from cucumber from four different regions of Oman and 16 isolates of muskmelon from the Batinah region in Oman were characterized for aggressiveness, sensitivity to metalaxyl and genetic diversity using AFLP fingerprinting. Twenty isolates of P. aphanidermatum from diverse hosts from different countries were also included in the study. Most isolates from Oman were found to be aggressive on cucumber seedlings and all were highly sensitive to metalaxyl (EC50 <0.80 μg mL-1). Isolates from cucumber and muskmelon were as aggressive as each other on both hosts (P > 0.05), which implies a lack of host specialization in P. aphanidermatum on these two hosts in Oman. AFLP analysis of all isolates using four primer-pair combinations resolved 152 bands, of which 61 (∼40%) were polymorphic. Isolates of P. aphanidermatum from Oman and other countries exhibited high genetic similarity (mean = 94.1%) and produced 59 different AFLP profiles. Analysis of molecular variance indicated that most AFLP variation among populations of P. aphanidermatum in Oman was associated with geographical regions (FST = 0.118; P <0.0001), not hosts (FST = -0.004; P = 0.4323). These data were supported by the high rate of recovery (24%) of identical phenotypes between cucumber and muskmelon fields in the same region as compared to the low recovery (10%) across regions in Oman, which suggests more frequent movement of Pythium inoculum among muskmelon and cucumber fields in the same region compared to movement across geographically separated regions. However, recovering clones among regions and different countries may imply circulation of Pythium inoculum via common sources in Oman and also intercontinental spread of isolates.

Original languageEnglish
Pages (from-to)45-56
Number of pages12
JournalPlant Pathology
Volume57
Issue number1
DOIs
Publication statusPublished - Feb 2008

Fingerprint

Pythium
Oman
Pythium aphanidermatum
Cucumis sativus
metalaxyl
cucumbers
aggression
genetic variation
muskmelons
Population
amplified fragment length polymorphism
inoculum
Amplified Fragment Length Polymorphism Analysis
Seedlings
Analysis of Variance
Clone Cells
clones
Phenotype
phenotype
seedlings

Keywords

  • AFLP
  • AMOVA
  • Damping-off
  • Genetic differentiation
  • Genetic similarity
  • Phenotypes

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science

Cite this

Genetic diversity, aggressiveness and metalaxyl sensitivity of Pythium aphanidermatum populations infecting cucumber in Oman. / Al-Sa'di, A. M.; Drenth, A.; Deadman, M. L.; Aitken, E. A B.

In: Plant Pathology, Vol. 57, No. 1, 02.2008, p. 45-56.

Research output: Contribution to journalArticle

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abstract = "Seventy three isolates of Pythium aphanidermatum obtained from cucumber from four different regions of Oman and 16 isolates of muskmelon from the Batinah region in Oman were characterized for aggressiveness, sensitivity to metalaxyl and genetic diversity using AFLP fingerprinting. Twenty isolates of P. aphanidermatum from diverse hosts from different countries were also included in the study. Most isolates from Oman were found to be aggressive on cucumber seedlings and all were highly sensitive to metalaxyl (EC50 <0.80 μg mL-1). Isolates from cucumber and muskmelon were as aggressive as each other on both hosts (P > 0.05), which implies a lack of host specialization in P. aphanidermatum on these two hosts in Oman. AFLP analysis of all isolates using four primer-pair combinations resolved 152 bands, of which 61 (∼40{\%}) were polymorphic. Isolates of P. aphanidermatum from Oman and other countries exhibited high genetic similarity (mean = 94.1{\%}) and produced 59 different AFLP profiles. Analysis of molecular variance indicated that most AFLP variation among populations of P. aphanidermatum in Oman was associated with geographical regions (FST = 0.118; P <0.0001), not hosts (FST = -0.004; P = 0.4323). These data were supported by the high rate of recovery (24{\%}) of identical phenotypes between cucumber and muskmelon fields in the same region as compared to the low recovery (10{\%}) across regions in Oman, which suggests more frequent movement of Pythium inoculum among muskmelon and cucumber fields in the same region compared to movement across geographically separated regions. However, recovering clones among regions and different countries may imply circulation of Pythium inoculum via common sources in Oman and also intercontinental spread of isolates.",
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