Potential of Eurasian poplar rust to overcome a major quantitative resistance factor |
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Authors: | A Dowkiw E Voisin C Bastien |
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Institution: | INRA, Unité de Recherche Amélioration Génétique et Physiologie Forestières, 2163 avenue de la Pomme de Pin, CS 40001 Ardon, 45075 Orléans Cedex 2, France |
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Abstract: | The effect of RUS, a major quantitative resistance (QR) factor inherited from Populus trichocarpa, was assessed in two Populus deltoides × P. trichocarpa F1 progenies against eight isolates of Melampsora larici‐populina, the causal agent of Eurasian poplar rust. Six isolates were identified on which RUS had no significant effect. The first RUS‐defeating isolate identified suggested a pre‐existing potential to overcome RUS in the pathogen’s populations. The P. deltoides genetic background made no difference either to the ability of a given isolate to overcome RUS or to the relative and absolute aggressiveness of the isolates. This study illustrates how extreme the isolate‐specificity of QR can be. It also yields insights into the relationship between size of uredinia and sporulation rate, discussing the epidemiological significance of spore production per mm2 uredinium. |
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Keywords: | Melampsora larici‐populina parasitic fitness Populus deltoides Populus trichocarpa pre‐adaptation resistance durability resistance erosion sporulation rate |
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