Australasian Plant Pathology

, Volume 34, Issue 3, pp 361–368 | Cite as

Molecular characterisation, pathogenesis and fungicide sensitivity of Pythium spp. from table beet (Beta vulgaris var. vulgaris) grown in the Lockyer Valley, Queensland

  • Paul T. Scott
  • Heidi L. Martin
  • Scott M. Boreel
  • Alan H. Wearing
  • Donald J. Maclean


Table beet production in the Lockyer Valley of south-eastern Queensland is known to be adversely affected by soilborne root disease from infection by Pythium spp. However, little is known regarding the species or genotypes that are the causal agents of both pre- and post-emergence damping off. Based on RFLP analysis with HhaI, Hinfl and MboI of the PCR amplified ITS region DNA from soil and diseased plant samples, the majority of 130 Pythium isolates could be grouped into three genotypes, designated LVP A, LVP B and LVP C. These groups comprised 43, 41 and 7% of all isolates, respectively. Deoxyribonucleic acid sequence analysis of the ITS region indicated that LVP A was a strain of Pythium aphanidermatum, with greater than 99% similarity to the corresponding P. aphanidermatum sequences from the publicly accessible databases. The DNA sequences from LVP B and LVP C were most closely related to P. ultimum and P. dissotocum, respectively. Lower frequencies of other distinct isolates with unique RFLP patterns were also obtained with high levels of similarity (>97%) to P. heterothallicum, P. periplocum and genotypes of P. ultimum other than LVP B. Inoculation trials of 1- and 4-week-old beet seedlings indicated that compared with isolates of the LVP B genotype, a higher frequency of LVP A isolates caused disease. Isolates with the LVP A, LVP B and LVP C genotypes were highly sensitive to the fungicide Ridomil MZ, which suppressed radial growth on V8 agar between approximately four and thirty fold at 5 μg/mL metalaxyl and 40 μg/mL mancozeb, a concentration far lower than the recommended field application rate.


Internal Transcribe Spacer Australasian Plant Pathology Metalaxyl PCNB Pimaricin 
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Copyright information

© Australasian Plant Pathology Society 2005

Authors and Affiliations

  • Paul T. Scott
    • 1
  • Heidi L. Martin
    • 2
  • Scott M. Boreel
    • 1
  • Alan H. Wearing
    • 3
  • Donald J. Maclean
    • 1
  1. 1.School of Agronomy and HorticultureThe University of QueenslandGattonAustralia
  2. 2.Department of Primary Industries and FisheriesHorticultural and Forestry Science, Gatton Research StationGattonAustralia
  3. 3.School of Molecular and Microbial SciencesThe University of QueenslandSt LuciaAustralia

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