Methods of Testing Apples for Resistance to Fire Blight

Kleinhempel, Helmut; Kegler, H.; Ficke, Werner; Schaefer, Hans-Jürgen

doi:10.17660/actahortic.1984.151.37

Cited by 5 publications

(4 citation statements)

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“…These authors measured the shoot length blighted, if necroses reached the stem, after 7 and 14 dpi. In the present study, the final degree of tissue area affected was recorded at a time (28 dpi) when the disease progress has already ceased (Kleinhempel et al. 1984).…”

Section: Discussionmentioning

confidence: 99%

“…In an assay similar to that of Kleinhempel et al (1984), shoots of 146 progeny, from four to 12 graftings on rootstock M9 for each individual, were inoculated in 2005 by incising the tips of the two upper leaves with scissors that had been dipped in a suspension of E. amylovora, strain 222 (10 9 cfu/ml). Only shoots with a minimum length of 25 cm were inoculated.…”

Section: Artificial Shoot Inoculationmentioning

confidence: 99%

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Strong evidence for a fire blight resistance gene of Malus robusta located on linkage group 3

Peil¹,

et al. 2007

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Fire blight (FB), caused by the Gram-negative bacterium Erwinia amylovora is a dangerous disease on pome fruit, including apple. The FB-susceptible cultivar ÔIdaredÕ was crossed with the resistant wild species clone Malus · robusta 5. A segregating population of 146 progeny has been tested by artificial shoot inoculation for susceptibility to FB. Progeny were infected from 0% to 100% of the shoot length. To identify chromosomal regions or loci responsible for resistance to FB of Malus · robusta 5, a set of microsatellite markers (simple sequence repeat, SSRs) was chosen covering all linkage groups of apple. Up to eight different microsatellites were bulked to one mutliplex PCR using four different labels and a fifth label for a size standard. Fifty-nine microsatellite markers out of 72 SSRs were polymorphic. Fifty-four of 66 loci detected could be mapped and were useful for the detection of related resistant loci. Alleles of microsatellites Hi03d06, CH03g07 and CH03e03 originating from the resistant donor M. robusta were associated with resistance to Erwinia amylovora. Up to eighty percent of the phenotypic variation could be explained by the interval spanned by SSRs CH03g07 and CH03e03, indicating the presence of a major resistance gene. All three microsatellites are located on the distal part of linkage group 3, spanning 15 cM. The SSR marker CH03e03 can be regarded as diagnostic marker for FB resistance. Only seven progeny expressing allele b (184 bp) of CH03e03 showed blighted shoot lengths of more than 30% and only nine progeny lacking allele b showed blighted shoot lengths of <30%. By setting a threshold of 30% shoot necrosis for resistance to FB, the 146 individuals segregate into 71 susceptible and 75 resistant plants, and resistance to FB maps 9 cM away from marker CH03e03.

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Section: Discussionmentioning

confidence: 99%

Section: Artificial Shoot Inoculationmentioning

confidence: 99%

Strong evidence for a fire blight resistance gene of Malus robusta located on linkage group 3

Peil¹,

et al. 2007

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“…In Germany, fire blight inoculations were performed in the greenhouse of the Institute for Resistance Research and Stress Tolerance Quedlinburg using a method modified to the assay of Kleinhempel et al (1984). Currently, 82 cvs from the genebank of the Institute for Breeding Research on Horticultural and Fruit Crops in Dresden-Pillnitz have been tested.…”

Section: Methodsmentioning

confidence: 99%

European pome fruit genetic resources evaluated for disease resistance

Kellerhals

Szalatnay

Hunziker

et al. 2011

Trees

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Pome fruit genetic resources collections constitute a highly valuable resource not only for fruit breeding but also for direct use by nurseries, growers, and home gardeners. In order to use these resources efficiently and sustainably, reliable evaluation data on fruit and tree characteristics must be generated. Here we focus on pome fruit genetic resources evaluated phenotypically and genotypically for susceptibility to apple scab (Venturia inaequalis), powdery mildew (Podosphaera leucotricha), fire blight (Erwinia amylovora), pear rust (Gymnosporangium sabinae) and storage diseases (e.g., Penicillium expansum). Examples are presented of several ongoing projects throughout Europe, with the aim to evaluate fruit genetic resources for disease susceptibility and potential use in breeding and for commercial use. The COST action 864 has fostered international cooperation in the evaluation of pome fruit genetic resources, and some of these evaluations therefore involve research groups from several of the participating countries.

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“…Although trees are infected by E . amylovora primarily through the flowers under natural conditions in the field [30, 31], resistance phenotyping in the genetic mapping studies listed above were performed by artificial inoculation of grafted scions in the glasshouse, using either the cut-leaf [32, 33] or the hypodermic needle technique [34]. In studies comparing the resistance of shoots and flowers, Thibault and Le Lezec [35] reported a weak correlation between them, while Maroofi and Mostafavi [36] found a positive association.…”

Section: Introductionmentioning

confidence: 99%

Mapping of fire blight resistance in Malus ×robusta 5 flowers following artificial inoculation

et al. 2019

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Background: Although the most common path of infection for fire blight, a severe bacterial disease on apple, is via host plant flowers, quantitative trait loci (QTLs) for fire blight resistance to date have exclusively been mapped following shoot inoculation. It is not known whether the same mechanism underlies flower and shoot resistance. Results: We report the detection of a fire blight resistance QTL following independent artificial inoculation of flowers and shoots on two F1 segregating populations derived from crossing resistant Malus ×robusta 5 (Mr5) with susceptible 'Idared' and 'Royal Gala' in experimental orchards in Germany and New Zealand, respectively. QTL mapping of phenotypic datasets from artificial flower inoculation of the 'Idared' × Mr5 population with Erwinia amylovora over several years, and of the 'Royal Gala' × Mr5 population in a single year, revealed a single major QTL controlling floral fire blight resistance on linkage group 3 (LG3) of Mr5. This QTL corresponds to the QTL on LG3 reported previously for the 'Idared' × Mr5 and an 'M9' × Mr5 population following shoot inoculation in the glasshouse. Interval mapping of phenotypic data from shoot inoculations of subsets from both flower resistance populations reconfirmed that the resistance QTL is in the same position on LG3 of Mr5 as that for flower inoculation. These results provide strong evidence that fire blight resistance in Mr5 is controlled by a major QTL on LG3, independently of the mode of infection, rootstock and environment. Conclusions: This study demonstrates for the first time that resistance to fire blight caused by Erwinia amylovora is independent of the mode of inoculation at least in Malus ×robusta 5.

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Methods of Testing Apples for Resistance to Fire Blight

Cited by 5 publications

References 0 publications

Strong evidence for a fire blight resistance gene of Malus robusta located on linkage group 3

Strong evidence for a fire blight resistance gene of Malus robusta located on linkage group 3

European pome fruit genetic resources evaluated for disease resistance

Mapping of fire blight resistance in Malus ×robusta 5 flowers following artificial inoculation

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