Genome mapping of an apple scab, a powdery mildew and a woolly apple aphid resistance gene from open-pollinated Mildew Immune Selection

Abstract

Apple is host to a wide range of pests and diseases, with several of these, such as apple scab, powdery mildew and woolly apple aphid, being major causes of damage in most areas around the world. Resistance breeding is an effective way of controlling pests and diseases, provided that the resistance is durable. As the gene pyramiding strategy for increasing durability requires a sufficient supply of resistance genes with different modes of action, the identification and mapping of new resistance genes is an ongoing process in breeding. In this paper, we describe the mapping of an apple scab, a powdery mildew and a woolly apple aphid gene from progeny of openpollinated mildew immune selection. The scab resistance gene Rvi16 was identified in progeny 93.051 G07-098 and mapped to linkage group 3 of apple. The mildew and woolly aphid genes were identified in accession 93.051 G02-054. The woolly aphid resistance gene Er4 mapped to linkage group 7 to a region close to where previously the genes Sd1 and Sd2, for resistance to the rosy apple leaf-curling aphid, had been mapped. The mildew resistance gene Pl-m mapped to the same region on linkage group 11 where Pl2 had been mapped previously. Flanking markers useful for markerassisted selection have been identified for each gene.

Characterization of the defence response to Venturia inaequalis in ‘Honeycrisp’ apple, its ancestors, and progeny

“…Auto-fluorescence under ultraviolet light has been used in several studies of the Malus-Venturia pathosystem to describe the incompatible reaction (Win et al, 2003;Bus et al, 2005aBus et al, , 2010Galli et al, 2010). Despite the clear visual clues provided by auto-fluorescence, little is known about the compounds involved in the resistance response.…”

Heritability of powdery mildew and scab resistance within apple progenies

“…This parental combination, therefore, should be chosen for larger utilisation in future breeding. Such a procedure is supported by broader recommendations in literature (Hampson et al 2009;Bus et al 2010).…”

“…Salm. belong on a worldwide scale among the most important apple diseases, and resistance breeding has long been applied to apples as a means to control their incidence (Bus et al 2010). Both fungal diseases can be controlled through treatments, but with considerable difficulties and costs, and with long-term consequences and negative effects both on the environment and on the quality of fruits (Holb 2009).…”

Excised Leaf Bioassay: Phenotypic Expression of Natural Resistance in Apple against the Obliquebanded Leafroller

“…Two other WAA resistance genes in Malus have been identified, Er2 from 'Robusta 5' [64] and Er3 from 'Aotea 1' [65], which led to the validation of markers for and mapping of the WAA resistance genes, Er1, Er2, Er3 [28]. The three Er genes, together with a fourth gene, Er4, allows for pyramiding in breeding programs to increase the durability of WAA resistance [29].…”

“…), and the Russian wheat aphid (Diuraphis noxia Mordvilko) [26]- [31] as well as diseases such as apple scab (Venturia inaequalis Cooke), powdery mildew (Podosphaera leucotricha Ellis and Everh. ), and fire blight (Erwinia amylovora Burrill) [29] [32] [33] [34]. Very little research has focused on apple resistance against chewing insect pests.…”