Determining Population Variation of Apple Powdery Mildew at the Molecular Level

Lesemann, Silke; Urbanietz, A.; Dunemann, Frank

doi:10.17660/actahortic.2004.663.29

Cited by 5 publications

(3 citation statements)

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“…Interaction with the environment was often used by the authors as the explanation for a 1-year QTL effect (Conner et al 1998, Atienza et al 2003. Physiological races of apple S t a n k i e w i c z -K o s y l , P i t e r a and G a w r o n s k i powdery mildew have been reported (Krieghoff 1995, Lesemann et al 2003) and this may provide a possible explanation for the association of some QTL in the clone U 211 with resistance in 1 year only. The amount of phenotypic variance explaining consecutive seasons of phenotypic assessment can support the hypothesis that the role of some QTL and their expression can depend on the developmental stage of the plant.…”

Section: Interval Mapping Of Powdery Mildew Resistancementioning

confidence: 99%

Mapping QTL involved in powdery mildew resistance of the apple clone U 211

2005

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Scab and powdery mildew, caused by Venturia inaequalis (Cke.) Wint. and Podosphaera leucotricha (Ellis et Ev.) Salm. are the most important apple diseases. The apple clone U 211 is resistant to scab and is also highly resistant to powdery mildew under field conditions. The interval mapping method was applied for the identification of genomic regions conferring U 211 resistance to powdery mildew. The genetic maps of the ÔIdaredÕ and U 211 genome sectors were constructed using amplified fragment lenght polymorphism and simple sequence repeat markers and 98 individuals from the progeny of the cross ÔIdaredÕ · U 211. On the basis of the phenotypic and molecular marker data 10 powdery mildew resistance quantitative trait loci (QTL) were identified in U 211 and ÔIdaredÕ. One of the QTL in the clone U 211 explained 48-72% of the phenotypic variation and its effect was stable over years.

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Section: Interval Mapping Of Powdery Mildew Resistancementioning

confidence: 99%

Mapping QTL involved in powdery mildew resistance of the apple clone U 211

2005

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“…This question has been resolved only for the resistance of MIS, for which it has been demonstrated that virulent isolates exist (Lespinasse, 1983). Tests carried out on plants grown in vitro (Krieghoff, 1995) or on detached leaves (Lesemann et al ., 2004) also suggested the existence of virulent isolates on M. robusta , M. zumi calocarpa , Malus micromalus , Malus hupehensis and several apple cultivars. However, the pathogenicity of these isolates was not tested on trees and the potential impact of these virulent isolates under orchard conditions is not known.…”

Section: Introductionmentioning

confidence: 99%

Breakdown of Pl2, a major gene of resistance to apple powdery mildew, in a French experimental orchard

Caffier¹,

Laurens

2005

Plant Pathology

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Pl2 , a major resistance gene to powdery mildew originating from Malus zumi , is mainly used in apple-breeding programmes. In an experimental orchard in France, an increase of susceptibility to powdery mildew was observed on apple genotypes carrying Pl2 . This increase of susceptibility could not be explained by an effect of the age of the trees, or by an effect of the amount of inoculum on expression of the resistance Pl2 . It was demonstrated by tests of pathogenicity in controlled conditions that isolates of Podosphaera leucotricha sampled in this orchard were virulent to Pl2 . The appearance of virulent isolates within 6 years after planting apple genotypes selected for the presence of Pl2 resulted in a breakdown of the resistance. Ten years after planting, the percentage of genotypes that were still resistant to powdery mildew varied between 2 and 56%, depending on the progenies. This suggested that additional quantitative resistance genes may influence the durability of the resistance Pl2 .

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“…In addition, there are several other Malus species known to be resistant, as well as a number of apple cultivars displaying variations of mildew tolerance. The existence of different physiological races of P. leucotricha has been demonstrated by pathogenicity tests based on fungal isolates (Krieghoff 1995, Lesemann et al. 2004, Urbanietz and Dunemann 2005) as well as under natural conditions in the orchard (Caffier and Laurens 2005).…”

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Mapping of the apple powdery mildew resistance gene Pl1 and its genetic association with an NBS‐LRR candidate resistance gene

Dunemann

Peil

Urbanietz³

et al. 2007

Plant Breeding

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Molecular markers for the major apple powdery mildew resistance gene Pl1 were identified and are presently used in marker‐assisted selection in apple breeding. However, the precise map position of the Pl1 gene in the apple genome was not known. The objectives of this investigation were the identification of the Malus linkage group (LG) carrying the Pl1 locus, mapping of the resistance gene by simple sequence repeat (SSR) markers, and the analysis of genetic associations between the Pl1 gene and the numerous NBS‐LRR resistance gene candidates already mapped in the apple genome. A two‐step linkage mapping was used, based on two different apple families. The identification of LG 12 carrying Pl1 was performed indirectly by mapping the SCAR marker AT20 in an apple progeny for which there was a core genetic map but no mildew data available. Then, the position of Pl1 on LG 12 was determined by SSR markers in a second population which has been scored for mildew over 6 years in a greenhouse and in the field. The SSR Hi07f01, previously mapped on LG 12 [Tree Genet. Genomes, 2 (2006), 202] cosegregated with AT20 and was closely linked (∼1 cM) to the Pl1 gene. The TIR‐NBS‐LRR resistance gene analogue 15G11 mapped by the SSCP technique was also closely linked to the Pl1 resistance locus and might be a candidate for Pl1 itself, a second powdery mildew major resistance gene (Pld, [Theor. Appl. Genet., 110 (2004), 175]), or two scab resistance genes (Vg, [IOBC/WPRS Bull., 23 (2000), 245]; Vb, [Genome, 49 (2006), 1238]) which all seem to be located in a common R gene cluster at the distal end of apple LG 12.

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Determining Population Variation of Apple Powdery Mildew at the Molecular Level

Cited by 5 publications

References 0 publications

Mapping QTL involved in powdery mildew resistance of the apple clone U 211

Mapping QTL involved in powdery mildew resistance of the apple clone U 211

Breakdown of Pl2, a major gene of resistance to apple powdery mildew, in a French experimental orchard

Mapping of the apple powdery mildew resistance gene Pl1 and its genetic association with an NBS‐LRR candidate resistance gene

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