University of Hertfordshire

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  • ppa_13236

    Accepted author manuscript, 1.94 MB, PDF document

  • ppa_13236

    Final published version, 1.62 MB, PDF document

  • Bruce Fitt
  • Fay Newbery
  • Michael Shaw
  • Faye Ritchie
  • Peter Gladders
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Original languageEnglish
Number of pages13
JournalPlant Pathology
Early online date20 Jul 2020
Publication statusE-pub ahead of print - 20 Jul 2020


It is important to understand the likely response of plant pathogens to increased temperatures due to anthropogenic climate change. This includes evolutionary change due to selection on genetically based variation in growth rate with temperature. We attempted to quantify this in two ways. First, radial mycelial growth rates in agar culture were determined for a collection of 44 English isolates of Leptosphaeria maculans and 17 isolates of L. biglobosa , at 14 temperatures. For L. maculans the genotypic variances in four parameters were measured: minimum temperature allowing growth, optimum temperature, growth rate at the optimum temperature and growth rate at the highest usable temperature, 31.8°C. The standard deviations were 0.068 °C , 1.28°C, 0.21 mm day‐1 and 0.31 mm day‐1 °C‐1 respectively. For L. biglobosa, these figures were, respectively: immeasurably small, 1.31 °C, 0.053 mm day‐1 and 0.53 mm day‐ °C‐1. In addition, the incidence and severity of phoma stem canker in planta over a natural growing cycle at four temperatures (16°C, 20°C, 24°C and 28°C) around the average culture optimum were determined. There was no correlation between in vitro and in planta growth, and the decrease in pathogen measures either side of the optimum temperature was much less for in planta growth than for in vitro growth. We conclude that both pathogens have the capacity to evolve to adapt to changes in environmental conditions, but that predictions of the effect of this adaptation, or estimates of heritability in natural conditions, cannot be made from measurements in vitro.


© 2020 The Authors. Plant Pathology published by John Wiley & Sons Ltd on behalf of British Society for Plant Pathology. This is an open access article under the terms of the Creative Commons Attribution License (, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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