Mapping of the apple scab-resistance gene Vb

Genome ◽  
2006 ◽  
Vol 49 (10) ◽  
pp. 1238-1245 ◽  
Author(s):  
N. Erdin ◽  
S. Tartarini ◽  
G.A.L. Broggini ◽  
F. Gennari ◽  
S. Sansavini ◽  
...  

Apple scab, caused by the fungus Venturia inaequalis , is the major production constraint in temperate zones with humid springs. Normally, its control relies on frequent and regular fungicide applications. Because this control strategy has come under increasing criticism, major efforts are being directed toward the breeding of scab-resistant apple cultivars. Modern apple breeding programs include the use of molecular markers, making it possible to combine several different scab-resistance genes in 1 apple cultivar (pyramiding) and to speed up the breeding process. The apple scab-resistance gene Vb is derived from the Siberian crab apple ‘Hansen’s baccata #2’, and is 1 of the 6 “historical” major apple scab-resistance genes (Vf, Va, Vr, Vbj, Vm, and Vb). Molecular markers have been published for all these genes, except Vr. In testcross experiments conducted in the 1960s, it was reported that Vb segregated independently from 3 other major resistance genes, including Vf. Recently, however, Vb and Vf have both been mapped on linkage group 1, a result that contrasts with the findings from former testcross experiments. In this study, simple sequence repeat (SSR) markers were used to identify the precise position of Vb in a cross of ‘Golden Delicious’ (vbvb) and ‘Hansen’s baccata #2’ (Vbvb). A genome scanning approach, a fast method already used to map apple scab-resistance genes Vr2 and Vm, was used, and the Vb locus was identified on linkage group 12, between the SSR markers Hi02d05 and Hi07f01. This finding confirms the independent segregation of Vb from Vf. With the identification of SSR markers linked to Vb, another major apple scab-resistance gene has become available; breeders can use it to develop durable resistant cultivars with several different resistance genes.

Genome ◽  
2005 ◽  
Vol 48 (4) ◽  
pp. 630-636 ◽  
Author(s):  
A Patocchi ◽  
M Walser ◽  
S Tartarini ◽  
G A.L Broggini ◽  
F Gennari ◽  
...  

For all known major apple scab resistance genes except Vr, molecular markers have been published. However, the precise position of some of these genes, in the apple genome, remains to be identified. Knowledge about the relative position of apple scab resistance genes is necessary to preliminarily evaluate the probability of success of their pyramidization. Pyramidization of different resistance genes into the same genotype is a reliable way to create cultivars with durable apple scab resistance. Applying the genome scanning approach (GSA), we identified the linkage group of the scab resistance gene Vm, derived from Malus micromalus, and we found a new molecular marker tightly associated with the gene. The simple sequence repeat Hi07h02, previously mapped on linkage group 17, cosegregates with the Vm gene (no recombinants in the 95 plants tested). The already published sequence-characterized amplified region Vm marker OPB12687 was found to be linked at about 5 cM from the resistance gene and, therefore, this marker also maps on linkage group 17 of apple. This is the first report of the discovery of a major apple scab resistance gene on linkage group 17. The advantages of using GSA for the identification of molecular markers for qualitative traits are discussed.Key words: Malus, Venturia inaequalis, mapping, simple sequence repeat.


Genome ◽  
2009 ◽  
Vol 52 (2) ◽  
pp. 129-138 ◽  
Author(s):  
Giovanni A.L. Broggini ◽  
Paolo Galli ◽  
Gabriella Parravicini ◽  
Luca Gianfranceschi ◽  
Cesare Gessler ◽  
...  

Molecular markers derived from resistance gene analogs of HcrVf2, the first apple resistance gene cloned, may pave the way to the cloning of additional apple scab resistance genes. The Malus ×domestica ‘Florina’ (Vf) bacterial artificial chromosome (BAC) genomic library was screened by hybridization using HcrVf2 as a probe. Positive BAC clones were assembled into contigs and microsatellite markers developed from each contig mapped. Only linkage groups 1 and 6 contained HcrVf2 paralogs. On linkage group 1, five loci in addition to the Vf locus were identified. A single locus was detected on linkage group 6. Representative BAC clones of these loci including the Vf locus were sequenced and the gene structure compiled. A total of 22 sequences, showing high sequence similarity to HcrVf2, were identified. Nine sequences were predicted to encode all seven protein domains described in HcrVf2, while three were truncated. Transcriptional analysis indicated that six genes with a complete HcrVf-like structure were constitutively expressed in young uninfected leaves of ‘Florina’. The map position of each HcrVf analog was compared with the location of the major apple scab resistance genes. None of the major genes conferring scab resistance co-localized with HcrVf paralogs, indicating that they are unlikely to belong to the leucine-rich repeat – transmembrane class, which includes the Vf gene.


2020 ◽  
Vol 36 ◽  
pp. 5-11
Author(s):  
Mădălina Militaru ◽  
Monica Sturzeanu ◽  
Adina Iancu

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.


2011 ◽  
Vol 47 (No. 4) ◽  
pp. 156-165 ◽  
Author(s):  
J. Patzak ◽  
F. Paprštein ◽  
A. Henychová

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.


Plant Disease ◽  
2015 ◽  
Vol 99 (3) ◽  
pp. 370-375 ◽  
Author(s):  
Valérie Caffier ◽  
Andrea Patocchi ◽  
Pascale Expert ◽  
Marie-Noëlle Bellanger ◽  
Charles-Eric Durel ◽  
...  

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.


Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2632
Author(s):  
Sewon Oh ◽  
Hyeondae Han ◽  
Daeil Kim

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.


2004 ◽  
Vol 109 (8) ◽  
pp. 1702-1709 ◽  
Author(s):  
M Gygax ◽  
L Gianfranceschi ◽  
R Liebhard ◽  
M Kellerhals ◽  
C Gessler ◽  
...  

2004 ◽  
Vol 94 (4) ◽  
pp. 370-379 ◽  
Author(s):  
F. Calenge ◽  
A. Faure ◽  
M. Goerre ◽  
C. Gebhardt ◽  
W. E. Van de Weg ◽  
...  

The major scab resistance gene Vf, extensively used in apple breeding programs, was recently overcome by the new races 6 and 7 of the fungal pathogen Venturia inaequalis. New, more durable, scab resistance genes are needed in apple breeding programs. F1 progeny derived from the cross between partially resistant apple cv. Discovery and apple hybrid ‘TN10-8’ were inoculated in the greenhouse with eight isolates of V. inaequalis, including isolates able to overcome Vf. One major resistance gene, Vg, and seven quantitative trait loci (QTL) were identified for resistance to these isolates. Three QTL on linkage group (LG)12, LG13, and LG15 were clearly isolate-specific. Another QTL on LG5 was detected with two isolates. Three QTL on LG1, LG2, and LG17 were identified with most isolates tested, but not with every isolate. The QTL on LG2 displayed alleles conferring different specificities. This QTL co-localized with the major scab resistance genes Vr and Vh8, whereas the QTL on LG1 colocalized with Vf. These results contribute to a better understanding of the genetic basis of the V. inaequalis-Malus × domestica interaction.


2001 ◽  
Vol 14 (4) ◽  
pp. 508-515 ◽  
Author(s):  
Boris A. Vinatzer ◽  
Andrea Patocchi ◽  
Luca Gianfranceschi ◽  
Stefano Tartarini ◽  
Hong-Bin Zhang ◽  
...  

Scab caused by the fungal pathogen Venturia inaequalis is the most common disease of cultivated apple (Malus × domestica Borkh.). Monogenic resistance against scab is found in some small-fruited wild Malus species and has been used in apple breeding for scab resistance. Vf resistance of Malus floribunda 821 is the most widely used scab resistance source. Because breeding a high-quality cultivar in perennial fruit trees takes dozens of years, cloning disease resistance genes and using them in the transformation of high-quality apple varieties would be advantageous. We report the identification of a cluster of receptor-like genes with homology to the Cladosporium fulvum (Cf) resistance gene family of tomato on bacterial artificial chromosome clones derived from the Vf scab resistance locus. Three members of the cluster were sequenced completely. Similar to the Cf gene family of tomato, the deduced amino acid sequences coded by these genes contain an extracellular leucine-rich repeat domain and a transmembrane domain. The transcription of three members of the cluster was determined by reverse transcription-polymerase chain reaction to be constitutive, and the transcription and translation start of one member was verified by 5′ rapid amplification of cDNA ends. We discuss the parallels between Cf resistance of tomato and Vf resistance of apple and the possibility that one of the members of the gene cluster is the Vf gene. Cf homologs from other regions of the apple genome also were identified and are likely to present other scab resistance genes.


HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 855C-855 ◽  
Author(s):  
Minou Hemmat ◽  
Norman F. Weeden ◽  
Susan K. Brown

Apple scab, Venturia inaequalis (Cke.) Wint., is one of the most damaging diseases of apples. Although fungicide sprays have been used to control the disease, genetic resistance in existing commercially important varieties would be desirable. Identification of molecular marker(s) would be helpful in devising biotechnological approaches to control the disease. We used bulk segregant analysis to identify RAPD markers that cosegregate or display a tight linkage with Vf gene in Prima × Spartan cross. Using this approach, we are saturating the region around the scab resistance gene for the purpose of bracketing the locus. We have identified several markers associated with the Vf locus. The closest markers have been isolated and sequenced to be used as SCARs. The relationship and distances of the markers with the Vf locus and other previously reported markers will be discussed.


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