A Molecular Marker Linked to a Scab Resistance Gene (Vf) in Apple

Apple scab, caused by Venturia inaequalis (Cke.) Wint., is the most serious disease of apple trees. Resistance to V. inaequalis, derived from the small-fruited species Malus floribunda 821, is determined by a major dominant gene Vf. Our major objective is to identify RAPD markers linked to the Vf gene. The approach in this paper is based on the introgression of the Vf gene from M. floribunda into commercial cultivars. Almost 200 random sequence decamer-primers have been used to screen a pair of bulked samples and the donor parent M. floribunda clone 821 for markers linked to the Vf gene conferring resistance to apple scab. A single primer has been identified which generated a PCR fragment, OPK16/1300, from the donor parent M. floribunda clone 821 and the scab-resistant selections/cultivars bulk, but not from the scab-susceptible recurrent parent bulk. Co-segregation analysis using a segregating apple progeny and polymorphism analysis of individual scab-resistant Coop selections/cultivars have confirmed that this marker is linked to the scab-resistance gene Vf. OPK16/1300 has since been cloned and sequenced. Sequence-specific primers of 25 oligonucleotides based on the marker have been synthesized and used to screen further M. floribunda clone 821, scab-susceptible apple cultivars, scab-resistant apple cultivars, and scab-resistant Coop selections. The sequence-specific primers have identified polymorphisms of OPK16/1300 based on the presence or absence of a single band.

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A Randomly Amplified Polymorphic DNA (RAPD) Marker Tightly Linked to the Scab-resistance Gene Vf in Apple

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.122.1.47 ◽

1997 ◽

Vol 122 (1) ◽

pp. 47-52 ◽

Cited By ~ 12

Author(s):

Hong Y. Yang ◽

Schuyler S. Korban ◽

Jutta Krüger ◽

Hanna Schmidt

Keyword(s):

Resistance Gene ◽

Venturia Inaequalis ◽

Rapd Marker ◽

Apple Scab ◽

Scab Resistance ◽

Polymorphism Analysis ◽

Recurrent Parent ◽

Specific Primers ◽

Apple Cultivars ◽

Donor Parent

Almost 200 random sequence decamer primers were used to screen a pair of bulked samples of apple (Malus ×domestica Borkh.) DNA and that of the donor parent Malus floribunda Sieb. clone 821 for molecular markers linked to the Vf gene conferring resistance to apple scab [Venturia inaequalis (Cke.) Wint.]. Identified was a single primer that generated a polymerase chain-reaction (PCR) fragment, OPAR4/1400, from the donor parent M. floribunda clone 821 and the scab-resistant selections/cultivars bulk, but not from the scab-susceptible recurrent-parent bulk. Cosegregation analysis using a segregating apple progeny and polymorphism analysis of individual scab-resistant selections/cultivars confirmed that this marker was linked to the scab-resistance gene Vf OPAR4/1400 was then cloned and sequenced. Sequence-specific primers of 25 oligonucleotides based on the marker were developed and used to screen further M. floribunda clone 821, scab-susceptible apple cultivars, scab-resistant apple cultivars, and scab-resistant Purdue, Rutgers, and Univ. of Illinois apple breeding program selections. The sequence-specific primers identified polymorphisms of OPAR4/1400 based on the presence or absence of a single band. This molecular marker is at a distance of about 3.6 cM from the Vf gene.

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A Novel Pear Scab (Venturia nashicola) Resistance Gene, Rvn3, from Interspecific Hybrid Pear (Pyrus pyrifolia × P. communis)

Plants ◽

10.3390/plants10122632 ◽

2021 ◽

Vol 10 (12) ◽

pp. 2632

Author(s):

Sewon Oh ◽

Hyeondae Han ◽

Daeil Kim

Keyword(s):

Resistance Gene ◽

Resistance Genes ◽

Interspecific Hybrid ◽

Dominant Gene ◽

Apple Scab ◽

Scab Resistance ◽

Hybrid Population ◽

Pyrus Pyrifolia ◽

Pear Scab ◽

Venturia Nashicola

Asian pear scab is a fungal disease caused by Venturia nashicola. The identification of genes conferring scab resistance could facilitate the breeding of disease-resistant cultivars. Therefore, the present study aimed to identify a scab-resistance gene using an interspecific hybrid population ((Pyrus pyrifolia × P. communis) × P. pyrifolia). Artificial inoculation of V. nashicola was carried out for two years. The segregation ratio (1:1) of resistant to susceptible individuals indicated that resistance to V. nashicola was inherited from P. communis and controlled by a single dominant gene. Based on two years phenotypic data with the Kruskal–Wallis test and interval mapping, 12 common markers were significantly associated with scab resistance. A novel scab resistance gene, Rvn3, was mapped in linkage group 6 of the interspecific hybrid pear, and co-linearity between Rvn3 and one of the apple scab resistance genes, Rvi14, was confirmed. Notably, an insertion in pseudo-chromosome 6 of the interspecific hybrid cultivar showed homology with apple scab resistance genes. Hence, the newly discovered Rvn3 was considered an ortholog of the apple scab resistance gene. Since the mapping population used in the present study is a pseudo-BC1 population, pyramiding of multiple resistance genes to pseudo-BC1 could facilitate the breeding of pear cultivars with durable resistance.

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Molecular screening of domestic apple cultivars for scab resistance genes in Greece

Czech Journal of Genetics and Plant Breeding ◽

10.17221/119/2019-cjgpb ◽

2020 ◽

Vol 56 (No. 4) ◽

pp. 165-169

Author(s):

Lefkothea Karapetsi ◽

Irini Nianiou-Obeidat ◽

Antonios Zambounis ◽

Maslin Osathanunkul ◽

Panagiotis Madesis

Keyword(s):

Resistance Genes ◽

Venturia Inaequalis ◽

Apple Scab ◽

Scab Resistance ◽

Molecular Screening ◽

Polygenic Resistance ◽

Main Target ◽

Efficient Control ◽

Apple Cultivars ◽

Efficient Breeding

Apple scab caused by Venturia inaequalis has the most destructive effects among other phytopathogens in apple crops all over the world. The integration of resistance genes from local and domestic cultivars is a prerequisite for the efficient control of this disease and is a main target in efficient breeding approaches. Across Greece, many domestic apple cultivars are reported without deep knowledge about the presence and diversity of scab resistance genes. In this study, the presence of five resistance genes (Rvi2, Rvi4, Rvi6, Rvi8 and Rvi11) was evaluated across twenty local and domestic apple genotypes, employing twelve molecular markers closely linked to known apple scab resistance loci. Significant differences and polymorphisms among the tested cultivars were detected suggesting that some of them carry a sufficient number of resistance genes. This observed genetic diversity could be exploited in ongoing breeding approaches as a natural source of polygenic resistance against apple scab.

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Ten Years of VINQUEST: First Insight for Breeding New Apple Cultivars With Durable Apple Scab Resistance

Plant Disease ◽

10.1094/pdis-11-19-2473-sr ◽

2020 ◽

Vol 104 (8) ◽

pp. 2074-2081 ◽

Cited By ~ 2

Author(s):

Andrea Patocchi ◽

Andreas Wehrli ◽

Pierre-Henri Dubuis ◽

Annemarie Auwerkerken ◽

Carmen Leida ◽

...

Keyword(s):

Resistance Genes ◽

Venturia Inaequalis ◽

Durable Resistance ◽

Apple Scab ◽

Resistance Breeding ◽

Scab Resistance ◽

Data Points ◽

Resistance Breakdown ◽

Apple Cultivars ◽

Apple Production

Apple scab, caused by Venturia inaequalis, is a major fungal disease worldwide. Cultivation of scab-resistant cultivars would reduce the chemical footprint of apple production. However, new apple cultivars carrying durable resistances should be developed to prevent or at least slow the breakdown of resistance against races of V. inaequalis. One way to achieve durable resistance is to pyramid multiple scab resistance genes in a cultivar. The choice of the resistance genes to be combined in the pyramids should take into account the frequency of resistance breakdown and the geographical distribution of apple scab isolates able to cause such breakdowns. In order to acquire this information and to make it available to apple breeders, the VINQUEST project ( www.vinquest.ch ) was initiated in 2009. Ten years after launching this project, 24 partners from 14 countries regularly contribute data. From 2009 to 2018, nearly 9,000 data points have been collected. This information has been used to identify the most promising apple scab resistance genes for developing cultivars with durable resistance, which to date are: Rvi5, Rvi11, Rvi12, Rvi14, and Rvi15. As expected, Rvi1, together with Rvi3 and Rvi8, were often overcome, and have little value for scab resistance breeding. Rvi10 may also belong to this group. On the other hand, Rvi2, Rvi4, Rvi6, Rvi7, Rvi9, and Rvi13 are still useful for breeding, but their use is recommended only in extended pyramids of ≥3 resistance genes.

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Successful intergeneric transfer of a major apple scab resistance gene (Rvi6) from apple to pear and precise comparison of the downstream molecular mechanisms of this resistance in both species

10.1101/2021.05.31.446424 ◽

2021 ◽

Author(s):

Laure PERCHEPIED ◽

Elisabeth CHEVREAU ◽

Elisa RAVON ◽

Sylvain GAILLARD ◽

Sandra PELLETIER ◽

...

Keyword(s):

Resistance Gene ◽

Molecular Mechanisms ◽

Systemic Acquired Resistance ◽

Venturia Inaequalis ◽

Apple Scab ◽

Defense Responses ◽

Scab Resistance ◽

European Pear ◽

Intergeneric Transfer ◽

Transgenic Apple

Background: Scab is the most important fungal disease of apple and pear. Apple (Malus x domestica Borkh.) and European pear (Pyrus communis L.) are genetically related but they are hosts of two different fungal species: Venturia inaequalis for apple and V. pyrina for European pear. The apple/V. inaequalis pathosystem is quite well known, whereas knowledge about the pear/V. pyrina pathosystem is still limited. The aim of our study was to analyse the mode of action of a major resistance gene of apple (Rvi6) in transgenic apple and pear plants interacting with the two scab species (V. inaequalis and V. pyrina), in order to determine the degree of functional transferability between the two pathosystems. Results: Transgenic pear clones constitutively expressing the Rvi6 gene from apple were compared to a scab transgenic apple clone carrying the same construct. After inoculation in greenhouse with V. pyrina, strong defense reactions and very limited sporulation were observed on all transgenic pear clones tested. Microscopic observations revealed frequent aborted conidiophores in the Rvi6 transgenic pear / V. pyrina interaction. The macro- and microscopic observations were very comparable to the Rvi6 apple / V. inaequalis interaction. However, this resistance in pear proved variable according to the strain of V. pyrina, and one of the strains tested overcame the resistance of most of the transgenic pear clones. Comparative transcriptomic analyses of apple and pear resistant interactions with V. inaequalis and V. pyrina, respectively, revealed different cascades of molecular mechanisms downstream of the pathogen recognition by Rvi6 in the two species. Signal transduction was triggered in both species with calcium (and G-proteins in pear) and interconnected hormonal signaling (jasmonic acid in pear, auxins in apple and brassinosteroids in both species), without involvement of salicylic acid. This led to the induction of defense responses such as a remodeling of primary and secondary cell wall, lipids biosynthesis (galactolipids in apple and cutin and cuticular waxes in pear), systemic acquired resistance signal generation (in apple) or perception in distal tissues (in pear), and the biosynthesis of phenylpropanoids (flavonoids in apple but also lignin in pear). Conclusion: This study is the first example of a successful intergeneric transfer of a resistance gene among Rosaceae, with a resistance gene functioning towards another species of pathogen.

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Successful intergeneric transfer of a major apple scab resistance gene (Rvi6) from apple to pear and precise comparison of the downstream molecular mechanisms of this resistance in both species

BMC Genomics ◽

10.1186/s12864-021-08157-1 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

L. Perchepied ◽

E. Chevreau ◽

E. Ravon ◽

S. Gaillard ◽

S. Pelletier ◽

...

Keyword(s):

Resistance Gene ◽

Molecular Mechanisms ◽

Systemic Acquired Resistance ◽

Venturia Inaequalis ◽

Apple Scab ◽

Defense Responses ◽

Scab Resistance ◽

European Pear ◽

Intergeneric Transfer ◽

Transgenic Apple

Abstract Background Scab is the most important fungal disease of apple and pear. Apple (Malus x domestica Borkh.) and European pear (Pyrus communis L.) are genetically related but they are hosts of two different fungal species: Venturia inaequalis for apple and V. pyrina for European pear. The apple/V. inaequalis pathosystem is quite well known, whereas knowledge about the pear/V. pyrina pathosystem is still limited. The aim of our study was to analyse the mode of action of a major resistance gene of apple (Rvi6) in transgenic apple and pear plants interacting with the two scab species (V. inaequalis and V. pyrina), in order to determine the degree of functional transferability between the two pathosystems. Results Transgenic pear clones constitutively expressing the Rvi6 gene from apple were compared to a scab transgenic apple clone carrying the same construct. After inoculation in greenhouse with V. pyrina, strong defense reactions and very limited sporulation were observed on all transgenic pear clones tested. Microscopic observations revealed frequent aborted conidiophores in the Rvi6 transgenic pear / V. pyrina interaction. The macro- and microscopic observations were very comparable to the Rvi6 apple / V. inaequalis interaction. However, this resistance in pear proved variable according to the strain of V. pyrina, and one of the strains tested overcame the resistance of most of the transgenic pear clones. Comparative transcriptomic analyses of apple and pear resistant interactions with V. inaequalis and V. pyrina, respectively, revealed different cascades of molecular mechanisms downstream of the pathogen recognition by Rvi6 in the two species. Signal transduction was triggered in both species with calcium (and G-proteins in pear) and interconnected hormonal signaling (jasmonic acid in pear, auxins in apple and brassinosteroids in both species), without involvement of salicylic acid. This led to the induction of defense responses such as a remodeling of primary and secondary cell wall, lipids biosynthesis (galactolipids in apple and cutin and cuticular waxes in pear), systemic acquired resistance signal generation (in apple) or perception in distal tissues (in pear), and the biosynthesis of phenylpropanoids (flavonoids in apple but also lignin in pear). Conclusion This study is the first example of a successful intergeneric transfer of a resistance gene among Rosaceae, with a resistance gene functioning towards another species of pathogen.

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MOLECULAR SCREENING OF SOME ROMANIAN APPLE CULTIVARS FOR SCAB RESISTANCE GENES

FRUIT GROWING RESEARCH ◽

10.33045/fgr.v36.2020.01 ◽

2020 ◽

Vol 36 ◽

pp. 5-11

Author(s):

Mădălina Militaru ◽

Monica Sturzeanu ◽

Adina Iancu

Keyword(s):

Molecular Markers ◽

Resistance Genes ◽

Venturia Inaequalis ◽

Apple Scab ◽

Scab Resistance ◽

Research Station ◽

Breeding Center ◽

Fruit Growing ◽

Apple Cultivars ◽

Almost All

Apple scab, incided by the fungus Venturia inaequalis (Cke.) Wint., is a devastating disease of apple reported from almost all apple producing Romanian areas, which causes up to 70% losses of production. Molecular markers were used for detection of scab resistance genes in 22 old and introduced apple cultivars ('Romus 3', 'Romus 5', 'Rebra', 'Rustic', 'Nicol', 'Colmar', 'Colonade', registered by Research Institute for Fruit Growing Pitesti; 'Generos', 'Iris', 'Irisem', 'Luca', 'Ciprian', 'Cezar', 'Remar', 'Valery', 'Real', registered by Research Station for Fruit Growing Voinesti, Dambovita; 'Aura', 'Starkprim', 'Ionaprim', 'Bistritean', registered by Research Station for Fruit Growing Bistrita and old cultivars: 'Domnesc', 'Cretesc'). The presence of scab resistance genes were detected using the molecular markers: AL-07 (SCAR), AM19 (SCAR), VfC for Rvi6 (Vf) gene, AD13 (SCAR) for Rvi4 (Vr1) gene, OPL19 (SCAR) for Rvi2 (Vh2) and Rvi8 (Vh8) genes and OPB12 (STS) for Rvi5 (Vm) gene. The Rvi6 gene was detected in 17 cultivars from different breeding center. The marker AD13 presents in genome of 8 cultivars, such as 'Romus 3', 'Romus 5', 'Generos', 'Iris', 'Irisem', 'Cezar', 'Remar', 'Aura'. The Rvi5 gene was revealed in 3 cultivars ('Nicol', 'Generos', 'Irisem'), only.

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Identification of apple scab and powdery mildew resistance genes in Czech apple (Malus × domestica) genetic resources by PCR molecular markers

Czech Journal of Genetics and Plant Breeding ◽

10.17221/140/2011-cjgpb ◽

2011 ◽

Vol 47 (No. 4) ◽

pp. 156-165 ◽

Cited By ~ 5

Author(s):

J. Patzak ◽

F. Paprštein ◽

A. Henychová

Keyword(s):

Molecular Markers ◽

Powdery Mildew ◽

Genetic Resources ◽

Resistance Genes ◽

Powdery Mildew Resistance ◽

Venturia Inaequalis ◽

Apple Scab ◽

Scab Resistance ◽

Mildew Resistance ◽

Apple Cultivars

The presence of genes for resistance to scab (Venturia inaequalis) and powdery mildew (Podosphaera leucotricha) was studied using molecular markers in a sample of 279 apple cultivars from the Czech collection of apple genetic resources. The sample comprised 37 cultivars supposed to have the Vf gene for scab resistance, 97 reference world cultivars and 145 old and local cultivars. Six PCR molecular markers for the scab resistance genes Vf, Vm, Vbj, Vr and Vh and three PCR molecular markers for the powdery mildew resistance genes Pl-w, Pl-1 and Pl-d were used. The marker for the major scab resistance gene Vf was detected in all cultivars supposed to have Vf, except in Romus 1, and in the three small-fruited cultivars Malus Evereste, Golden Gem and Hilleri. The markers of the Vr and Vh scab resistance genes were detected in 22 cultivars in combination with the marker for Vf, in 56 reference world cultivars and in 82 old and local apple cultivars. PCR molecular markers for one or two of the powdery mildew resistance genes were detected in the small-fruited cultivars Malus Evereste, Golden Gem, prof. Sprengeri and Hilleri; and in the larger fruited cultivars Hagloe Crab, Borovinka and Tita Zetei. We did not find markers for the scab resistance genes Vm and Vbj in any of the studied cultivars. They are absent also in the remaining part of the Czech collection of apple genetic resources. PCR molecular markers are useful tools for the identification of resistance genes within apple germplasm collections and can be used to increase the number of sources for disease resistance in breeding programmes.

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Virulence Characterization of Venturia inaequalis Reference Isolates on the Differential Set of Malus Hosts

Plant Disease ◽

10.1094/pdis-07-14-0708-re ◽

2015 ◽

Vol 99 (3) ◽

pp. 370-375 ◽

Cited By ~ 13

Author(s):

Valérie Caffier ◽

Andrea Patocchi ◽

Pascale Expert ◽

Marie-Noëlle Bellanger ◽

Charles-Eric Durel ◽

...

Keyword(s):

Resistance Gene ◽

Resistance Genes ◽

Venturia Inaequalis ◽

Apple Scab ◽

Scab Resistance ◽

Reference Set ◽

Major Resistance Gene ◽

Differential Hosts ◽

Major Resistance Genes

A set of differential hosts has recently been identified for 17 apple scab resistance genes in an updated system for defining gene-for-gene (GfG) relationships in the Venturia inaequalis-Malus pathosystem. However, a set of reference isolates characterized for their complementary avirulence alleles is not yet available. In this paper, we report on improving the set of differential hosts for h(7) and propose the apple genotype LPG3-29 as carrying the single major resistance gene Rvi7. We characterized a reference set of 23 V. inaequalis isolates on 14 differential apple hosts carrying major resistance genes under controlled conditions. We identified isolates that were virulent on at least one of the following defined resistance gene hosts: h(1), h(2), h(3), h(4), h(5), h(6), h(7), h(8), h(9), h(10), and h(13). Sixteen different virulence patterns were observed. In general, the isolates carried one to three virulences, but some of them were more complex, with up to six virulences. This set of well-characterized isolates will be helpful for the identification of additional apple scab resistance genes in apple germplasm and the characterization of new GfG relationships to help improve our understanding of the host-pathogen interactions in the V. inaequalis-Malus pathosystem.

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Breakdown of the Scab Resistance Gene Vf in Apple Leads to a Founder Effect in Populations of the Fungal Pathogen Venturia inaequalis

Phytopathology ◽

10.1094/phyto.2004.94.4.364 ◽

2004 ◽

Vol 94 (4) ◽

pp. 364-369 ◽

Cited By ~ 42

Author(s):

Fabien Guérin ◽

Bruno Le Cam

Keyword(s):

Resistance Gene ◽

Founder Effect ◽

Allelic Variation ◽

Venturia Inaequalis ◽

Apple Scab ◽

Apple Orchard ◽

Scab Resistance ◽

Vf Gene ◽

Major Resistance Gene ◽

High Level

The recent breakdown of Vf, a major resistance gene to apple scab, provided an opportunity to analyze a population genetic process within the matching virulent subpopulation of the fungus Venturia inaequalis. We utilized the amplified fragment length polymorphism technique and allelic variation at four microsatellite loci to assess genetic structure of 133 isolates of V. inaequalis from a single commercial apple orchard sampled from one cultivar carrying the Vf gene (Judeline) and three cultivars devoid of the Vf gene. Both analyses indicated a strong decrease of the genetic diversity among isolates from the Vf cultivar compared with the high level of diversity among isolates from the three other cultivars. This leads to a high genetic differentiation between virVf and avrVf groups (FST > 0.17). Analyses of the genetic distance between AFLP patterns based on the Jaccard index indicate that all virVf isolates could be assigned to a single clonal lineage. These results lead us to conclude that the clonal structure of the population isolated from the Vf cultivar is an example of a founder effect in response to a resistance gene breakdown and it is likely that this event occurred in the orchard during the sampling year.

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