QTL analysis for aphid resistance and growth traits in apple

Abstract

The rosy apple aphid (Dysaphis plantaginea), the leaf-curling aphid (Dysaphis cf. devecta) and the green apple aphid (Aphis pomi) are widespread pest insects that reduce growth of leaves, fruits and shoots in apple (Malus × domestica). Aphid control in apple orchards is generally achieved by insecticides, but alternative management options like growing resistant cultivars are needed for a more sustainable integrated pest management (IPM). A linkage map available for a segregating F 1 -cross of the apple cultivars 'Fiesta' and 'Discovery' was used to investigate the genetic basis of resistance to aphids. Aphid infestation and plant growth characteristics were repeatedly assessed for the same 160 apple genotypes in three different environments and 2 consecutive years. We identified amplified fragment length polymorphism (AFLP) markers linked to quantitative trait loci (QTLs) for resistance to D. plantaginea ('Fiesta' linkage group 17, locus 57.7, marker E33M35-0269; heritability: 28.3%), and to D. cf. devecta ('Fiesta' linkage group 7, locus 4.5, marker E32M39-0195; heritability: 50.2%). Interactions between aphid species, differences in climatic conditions and the spatial distribution of aphid infestation were identified as possible factors impeding the detection of QTLs. A pedigree analysis of simple sequence repeat (SSR) marker alleles closely associated with the QTL markers revealed the presence of the alleles in other apple cultivars with reported aphid resistance ('Wagener', 'Cox's Orange Pippin'), highlighting the genetic basis and also the potential for gene pyramiding of aphid resistance in apple. Finally, significant QTLs for shoot length and stem diameter were identified, while there was no relationship between aphid resistance and plant trait QTLs.

Co-localisation of host plant resistance QTLs affecting the performance and feeding behaviour of the aphid Myzus persicae in the peach tree

“…QTLs whose expression differs across environments seem to be the rule rather than the exception in tree species (Asíns et al, 1994;Emebiri et al, 1998;García et al, 2000). Concerning the influence of growth characteristics of the host plant on resistance to aphid infestation, the effects of neighbouring tree infestation levels and/or different climatic conditions at the experimental site may impede the identification of genetically based resistance (Stoeckli et al, 2008). In this study, significant QTLs common to both trials were detected, although the test conditions varied (greenhouse versus shelter, saplings versus 2-year-old trees, monoclonal aphid colony versus a mixture of genotypes for infestation).…”

“…Studies on trees have been far less abundant. In apple, Stoeckli et al (2008) studied the relationship between aphid resistance and plant growth traits because, in addition to variations in plant chemistry, shoot growth characteristics may also influence plant susceptibility to pests. The authors identified significant QTLs for resistance to three aphid species and QTLs for plant shoot length and stem diameter.…”

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

“…devecta Wlk. ), 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].…”

Phenotypic and Molecular Screening of Apple Genotypes to Woolly Apple Aphid Resistance

“…Some quantitative trait loci (QTLs) were identified associated with aphid resistance in apple. Molecular markers were discovered linked to QTLs for resistance to the rosy apple aphid, the leaf-curling aphid and the green apple aphid (Stoeckli et al, 2008). Recently, progresses have been achieved regarding the development of molecular markers associated with WAA resistance genes (i.e.…”