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

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.

Download Full-text

Identification by genome scanning approach (GSA) of a microsatellite tightly associated with the apple scab resistance gene Vm

Genome ◽

10.1139/g05-036 ◽

2005 ◽

Vol 48 (4) ◽

pp. 630-636 ◽

Cited By ~ 49

Author(s):

A Patocchi ◽

M Walser ◽

S Tartarini ◽

G A.L Broggini ◽

F Gennari ◽

...

Keyword(s):

Molecular Markers ◽

Linkage Group ◽

Resistance Gene ◽

Resistance Genes ◽

Simple Sequence Repeat ◽

Apple Scab ◽

Scab Resistance ◽

Sequence Repeat ◽

Genome Scanning ◽

Simple Sequence

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.

Download Full-text

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

HortScience ◽

10.21273/hortsci.31.4.619a ◽

1996 ◽

Vol 31 (4) ◽

pp. 619a-619

Author(s):

Hong Y. Yang ◽

Schuyler S. Korban ◽

Jutta Kruger ◽

Hanna Schmidt

Keyword(s):

Resistance Gene ◽

Venturia Inaequalis ◽

Dominant Gene ◽

Apple Scab ◽

Scab Resistance ◽

Polymorphism Analysis ◽

Recurrent Parent ◽

Specific Primers ◽

Apple Cultivars ◽

Donor Parent

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.

Download Full-text

HcrVf paralogs are present on linkage groups 1 and 6 of Malus

Genome ◽

10.1139/g08-115 ◽

2009 ◽

Vol 52 (2) ◽

pp. 129-138 ◽

Cited By ~ 17

Author(s):

Giovanni A.L. Broggini ◽

Paolo Galli ◽

Gabriella Parravicini ◽

Luca Gianfranceschi ◽

Cesare Gessler ◽

...

Keyword(s):

Linkage Group ◽

Resistance Gene ◽

Resistance Genes ◽

Genomic Library ◽

Sequence Similarity ◽

Apple Scab ◽

Scab Resistance ◽

Transcriptional Analysis ◽

Linkage Groups ◽

Bac Clones

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.

Download Full-text

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.

Download Full-text

A new pear scab resistance gene Rvp1 from the European pear cultivar ‘Navara’ maps in a genomic region syntenic to an apple scab resistance gene cluster on linkage group 2

Tree Genetics & Genomes ◽

10.1007/s11295-011-0419-x ◽

2011 ◽

Vol 8 (1) ◽

pp. 53-60 ◽

Cited By ~ 16

Author(s):

Lydie Bouvier ◽

Marie Bourcy ◽

Mathieu Boulay ◽

Marie Tellier ◽

Philippe Guérif ◽

...

Keyword(s):

Linkage Group ◽

Gene Cluster ◽

Resistance Gene ◽

Apple Scab ◽

Genomic Region ◽

Scab Resistance ◽

Pear Cultivar ◽

European Pear ◽

Pear Scab ◽

Group 2

Download Full-text

Mapping of the apple scab-resistance gene Vb

Genome ◽

10.1139/g06-096 ◽

2006 ◽

Vol 49 (10) ◽

pp. 1238-1245 ◽

Cited By ~ 33

Author(s):

N. Erdin ◽

S. Tartarini ◽

G.A.L. Broggini ◽

F. Gennari ◽

S. Sansavini ◽

...

Keyword(s):

Molecular Markers ◽

Linkage Group ◽

Resistance Gene ◽

Ssr Markers ◽

Resistance Genes ◽

Venturia Inaequalis ◽

Apple Scab ◽

Scab Resistance ◽

Fast Method ◽

A Genome

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.

Download Full-text

Pathogenic Specialization of Venturia nashicola, Causal Agent of Asian Pear Scab, and Resistance of Pear Cultivars Kinchaku and Xiangli

Phytopathology ◽

10.1094/phyto-06-20-0220-r ◽

2020 ◽

Author(s):

Hideo Ishii ◽

Kumiko Nishimura ◽

Kenji Tanabe ◽

Yuichi Yamaoka

Keyword(s):

Resistance Breeding ◽

Scab Resistance ◽

Japanese Pear ◽

Pyrus Pyrifolia ◽

Asian Pear ◽

Sexual Recombination ◽

Venturia Nashicola ◽

Race 1 ◽

New Races ◽

Race 2

Scab, caused by Venturia nashicola is one of the most serious diseases of Asian pears including Japanese pear (Pyrus pyrifolia var. culta) and Chinese pears (P. bretschneideri and P. ussuriensis). Breeding of scab-resistant pear cultivars is essential to minimize the use of fungicides and the risk of fungicide resistance developing in the pathogen. A survey of pathogenic specialization in V. nashicola is needed to ensure durable scab resistance in cultivated pears. Race 1, 2, and 3 isolates of V. nashicola, each differing in pathogenicity to Japanese pear cv. Kousui and Asian pear strain Mamenashi 12, have been reported from Japan. In the present study, isolates collected from scabbed pears in China and Taiwan were classified as V. nashicola based on conidial size and mating ability. However, various isolates were found to have pathogenicity distinct from races 1, 2, and 3 in tests on seven differential host genotypes: Kousui; Mamenashi 12; Chinese pear cvs. Jingbaili, Yali, Linyuli, Nanguoli; and Taiwanese pear cv. Hengshanli. The new races were designated as races 4 to 7. Progenies characteristic of race 3 isolates were produced in a cross between race 1 and race 2 isolates, suggesting the possible role of sexual recombination in the emergence of novel races. Japanese pear cv. Kinchaku and cv. Xiangli of P. sinkiangensis (Korla fragrant pear grown in China) didn’t show visible symptoms after inoculation with any of the seven races. The broad scab resistance in Kinchaku and Xiangli makes them a promising genetic resource for resistance breeding programs.

Download Full-text

Molecular markers linked to the apple scab resistance gene Vbj derived from Malus baccata jackii

Theoretical and Applied Genetics ◽

10.1007/s00122-004-1803-9 ◽

2004 ◽

Vol 109 (8) ◽

pp. 1702-1709 ◽

Cited By ~ 71

Author(s):

M Gygax ◽

L Gianfranceschi ◽

R Liebhard ◽

M Kellerhals ◽

C Gessler ◽

...

Keyword(s):

Molecular Markers ◽

Resistance Gene ◽

Apple Scab ◽

Scab Resistance ◽

Malus Baccata

Download Full-text

Quantitative Trait Loci (QTL) Analysis Reveals Both Broad-Spectrum and Isolate-Specific QTL for Scab Resistance in an Apple Progeny Challenged with Eight Isolates of Venturia inaequalis

Phytopathology ◽

10.1094/phyto.2004.94.4.370 ◽

2004 ◽

Vol 94 (4) ◽

pp. 370-379 ◽

Cited By ~ 122

Author(s):

F. Calenge ◽

A. Faure ◽

M. Goerre ◽

C. Gebhardt ◽

W. E. Van de Weg ◽

...

Keyword(s):

Quantitative Trait Loci ◽

Resistance Gene ◽

Resistance Genes ◽

Quantitative Trait ◽

Venturia Inaequalis ◽

Scab Resistance ◽

Breeding Programs ◽

Apple Breeding ◽

Trait Loci ◽

New Races

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.

Download Full-text