Development of apple powdery mildew on sources of resistance to Podosphaera leucotricha, exposed to an inoculum virulent against the major resistance gene Pl-2

The major resistance gene Pl-2 in apple has recently been shown to be overcome by a virulent population of powdery mildew, Podosphaera leucotricha, in genotypes of the fourth generation after introgression of Pl-2 from crab apple, Malus zumi. Tests of pathogenicity in controlled conditions and obser...

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Bibliographic Details
Published in:Plant breeding 2007-06, Vol.126 (3), p.319-322
Main Authors: Caffier, V, Parisi, L
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Biological and medical sciences
Decapoda
Fundamental and applied biological sciences. Psychology
Genetics and breeding of economic plants
Life Sciences
Malus
Malus x domestica
Malus × domestica
Pl-2
Podosphaera leucotricha
resistance
Varietal selection. Specialized plant breeding, plant breeding aims
Vegetal Biology
virulence
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Summary:The major resistance gene Pl-2 in apple has recently been shown to be overcome by a virulent population of powdery mildew, Podosphaera leucotricha, in genotypes of the fourth generation after introgression of Pl-2 from crab apple, Malus zumi. Tests of pathogenicity in controlled conditions and observations in an orchard showed that the initial progenitor of Pl-2, MAL 68/1, was overcome by a virulent inoculum. As a consequence, all selections derived from MAL 68/1 may lose their resistance to powdery mildew, if Pl-2 is used alone. Sources of resistance other than Pl-2 remained efficient to the virulent population: M. hupehensis, M. mandshurica, M. robusta, M. sargentii, M. sieboldii, D12, Mildew Immune Selection and 'White Angel'. The combination of Pl-2 with quantitative resistance genes resulted in a high level of resistance.
ISSN:0179-9541
1439-0523
DOI:10.1111/j.1439-0523.2007.01351.x