Étude des conditions de l'émergence du phytophthora alni sur l'aulne glutineux

Abstract : Since the early 1990's alder decline caused by the oomycete Phytophthora alni subsp. alni (Paa) is one of the most important threats to riparian ecosystems in Europe. The emergence of Paa is related to an interspecific hybridization event between two related species -initially considered as Paa variants- misnamed as Phytophthora alni subsp. uniformis (Pau) and Phytophthora alni subsp. multiformis (Pam). The objective of this thesis was to identify the factors that may have contributed to the emergence of the disease in Europe. Following a population genetics approach we showed that Pau is likely to be an invasive species in Europe, probably native to North America. Its introduction would have enabled hybridization with Pam and, consequently be a major cause on the emergence of Paa. Our results confirm that Paa has arisen from several hybridization events, which have geographically structured its European populations. Paa's genetic variability, revealed by microsatellite markers, showed low levels of polymorphism, with a dominant genotype scattered throughout Europe. In addition, a modelling approach revealed that alders' crown decline is linked to temperature. In particular, the disease incidence increases during mild winters which favours mycelium survival as Paa does not produce resistant spores (chlamydospores or oospores). The effect of summer temperatures is more complex to explain. Disease incidence decreases when summer temperatures are higher, but this phenomenon can also be linked to the physiological conditions of trees or changes in soil microbiological communities. Conversely, tree recovery is favoured by lower winter and higher summer temperatures. Climate change does not explain the emergence of the disease. However, increases in winter temperatures du to climate change may strengthen the epidemic
Document type :
Theses
Complete list of metadatas

Cited literature [176 references]  Display  Hide  Download

https://hal.univ-lorraine.fr/tel-01749348
Contributor : Thèses Ul <>
Submitted on : Thursday, March 29, 2018 - 12:13:49 PM
Last modification on : Wednesday, April 11, 2018 - 1:30:26 AM
Long-term archiving on: Friday, September 14, 2018 - 7:39:22 AM

File

DDOC_T_2012_0153_AGUAYO_SILVA....
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01749348, version 1

Collections

Citation

Jaime Christián Aguayo Silva. Étude des conditions de l'émergence du phytophthora alni sur l'aulne glutineux. Biologie végétale. Université de Lorraine, 2012. Français. ⟨NNT : 2012LORR0153⟩. ⟨tel-01749348⟩

Share

Metrics

Record views

43

Files downloads

171