European Journal of Plant Pathology (2006) 116, 315-324

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D. Blachinsky, D. Shtienberg, E. Zamski, D. Weinthal and S. Manulis (2006)
Effects of pear tree physiology on fire blight progression in perennial branches and on expression of pathogenicity genes in Erwinia amylovora
European Journal of Plant Pathology 116 (4), 315-324
Abstract: The interaction between Erwinia amylovora (the causal agent of fire blight) and the physiological status of pear trees was examined under orchard conditions. The physiological status of the trees was defined qualitatively, using host phenology and vigour as measures, and quantitatively, using the sorbitol content in annual shoots as a measure. Qualitatively, tree response to fire blight was governed by phenological stage at the time of infection and vigour: low vigour trees inoculated in the autumn (just before entering dormancy) and high vigour trees inoculated in the spring (soon after bloom) were more susceptible than high vigour trees inoculated in the autumn and low vigour trees inoculated in the spring. Quantitatively, the rate of symptom progression in perennial branches (SPR) was significantly (P < 0.001) correlated to the absolute value of the rate of sorbitol content change [SCR]. The relationship between hrp genes expression of transformed E. amylovora (estimated according to hrpE and hrpJ expression) and [SCR] was determined on 1 year-old trees. Expression of hrp genes was significantly correlated with [SCR] (P = 0.004) and 63.5% of the variability in the hrp genes expression was attributed to [SCR] values. The expression of hrp genes increased gradually and asymptotically with increasing [SCR] values; further increase in [SCR] did not affect the expression.
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Link to article at publishers website
Database assignments for author(s): D. Shtienberg

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution
resistance/tolerance/defence of host

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Erwinia amylovora Pear (Pyrus)