scholarly journals Scab resistance in Malus sp. progenies - inheritance and resistance stability

2003 ◽  
Vol 9 (1) ◽  
Author(s):  
M. G. Tóth ◽  
Sz. Kovács ◽  
Zs. D. Rozsnyay
Keyword(s):  
Open Field ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Female Parent ◽  
Male Parent ◽  
Scab Resistance ◽  
Malus Prunifolia ◽  
Malus Floribunda ◽  
Artificial Inoculations ◽  
Positive Effect

Susceptibility of progenies of some Ma/us species to apple scab was evaluated. Susceptibility of hybrid families was observed first in greenhouse after artificial inoculations by the suspension of the pathogen, Venturia inaequalis (Cooke) Wint., then in open field. The Hungarian type of Malus floribunda, which proved to be scab resistant in our examinations, has a positive effect on the segregation of progenies to resistant and susceptible individuals as a male parent, not depending on the rate of susceptibility of the other parent. However, the German type of Malus floribunda and Malus prunifolia act as dominant, highly susceptible parents. Malus x purpurea and Malus baccata, which proved to be highly susceptible to apple scab in open field and in artificial inoculations, transmits its susceptibility only slightly to its progenies as a male parent. According to our experiments, the inheritance of scab resistance of Malus floribunda cannot be considered as monogenic, as published by other authors. Scab susceptibility of parents influences the segregation of progenies to resistant or susceptible individuals. The moderately scab susceptible `Idared' as female parent has a statistically proved positive effect on the segregation of its progenies. More factors indicate the appearance of a new race of Venturia inaequalis (Cke.) Wint.: change of the symptoms in the greenhouse; considerable increase of susceptible individuals after greenhouse inoculation in 1997; more and more progenies of the male parent Malus floribunda became susceptible to scab in open field.

scholarly journals New North American isolates of Venturia inaequalis can overcome apple scab resistance of Malus floribunda 821

2019 ◽  
Author(s):  
David Papp ◽  
Jugpreet Singh ◽  
David Gadoury ◽  
Awais Khan
Keyword(s):  
New York ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Venturia Inaequalis ◽  
Durable Resistance ◽  
Apple Scab ◽  
Scab Resistance ◽  
Breeding Programs ◽  
Malus Floribunda

AbstractApple scab, caused by Venturia inaequalis (Cke.) Wint., is a destructive fungal disease of major apple cultivars worldwide, most of which are moderately to highly susceptible. Thus, development of scab resistant cultivars is one of the highest priorities of apple breeding programs. The principal source of resistance for breeding programs has been the scab resistance gene Rvi6 that originated from the Japanese crabapple Malus floribunda (Sieb.) sel. 821. Isolates of V. inaequalis able to overcome Rvi6 have been identified in Europe, but have not yet been reported on the American continents. We recently discovered scab infection on M. floribunda 821 trees in a research orchard at Geneva, New York, USA, where approximately 10% of the leaves bore profusely sporulating apple scab lesions, many of which had coalesced to cover entire leaves. Chlorosis and pinpoint pitting symptoms typical of failed infections by V. inaequalis on hosts bearing the Rvi6 and Rvi7 genes were also observed. We assessed genetic diversity and population genetic structure of six V. inaequalis isolates collected from M. floribunda 821, one isolate from ‘Nova Easygro’, one isolate from ‘Golden Delicious’ and two isolates from Europe (11 isolates in total) using 16,321 genome-wide SNPs. Population genetic structure and PCA separated the isolates into distinct European and USA groups. The forgoing suggests that the new Rvi6 virulent isolates emerged within USA populations, rather than being transported from Europe. The overcoming of resistance in M. floribunda 821 but not in descendant cultivars suggests that durable resistance to apple scab will require a more comprehensive understanding of Rvi6 mediated resistance in diverse genetic backgrounds.

scholarly journals New North American Isolates of Venturia inaequalis Can Overcome Apple Scab Resistance of Malus floribunda 821

Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 649-655 ◽  
Author(s):  
David Papp ◽  
Jugpreet Singh ◽  
David Gadoury ◽  
Awais Khan
Keyword(s):  
Genetic Structure ◽  
Population Genetic Structure ◽  
North American ◽  
Population Genetic ◽  
Venturia Inaequalis ◽  
Durable Resistance ◽  
Apple Scab ◽  
Scab Resistance ◽  
Breeding Programs ◽  
Malus Floribunda

Apple scab, caused by Venturia inaequalis, is a destructive fungal disease of major apple cultivars worldwide, most of which are moderately to highly susceptible. Thus, development of scab resistant cultivars is one of the highest priorities of apple breeding programs. The principal source of resistance for breeding programs has been the scab resistance gene Rvi6 that originated from the Japanese crabapple Malus floribunda (Sieb.) sel. 821. Isolates of V. inaequalis able to overcome Rvi6 have been identified in Europe, but have not yet been reported on the American continents. We recently discovered scab infection on M. floribunda 821 trees in a research orchard at Geneva, NY, U.S.A., where approximately 10% of the leaves bore profusely sporulating apple scab lesions, many of which had coalesced to cover entire leaves. We observed both chlorosis, typical to Rvi6, and pinpoint pitting symptoms typical to failed infections by V. inaequalis on hosts bearing the Rvi7 gene. We assessed genetic diversity and population genetic structure of 11 V. inaequalis isolates in total, of North American and European origin, isolated from M. floribunda 821, ‘Nova Easygro’, ‘Golden Delicious’, TSR33T239, ‘Schone van Boskoop’, and ‘Prima’, using 16,321 genome-wide SNPs. Population genetic structure and PCA separated the isolates into distinct European and U.S. groups. The forgoing suggests that the new Rvi6 virulent isolates emerged within U.S. populations, rather than being transported from Europe. The complete resistance breakdown in M. floribunda 821 but not in descendant cultivars, which kept their field resistance, suggests that durable resistance to apple scab will require a more comprehensive understanding of Rvi6 mediated resistance in diverse genetic backgrounds.

scholarly journals Evaluation of Apple Scab Resistance of Malus sieversii Populations from Central Asia

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 440A-440 ◽  
Author(s):  
H.S. Aldwinckle ◽  
P.L. Forsline ◽  
H.L. Gustafson ◽  
S.C. Hokanson
Keyword(s):  
Central Asia ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Scab Resistance ◽  
Type Reaction ◽  
Malus Sieversii ◽  
Horticultural Traits ◽  
Malus Floribunda ◽  
Seed Collections ◽  
Made In

Resistance to apple scab (Venturia inaequalis) in apple cultivar breeding has been derived mainly from the Vf gene from Malus floribunda 821, which introgresses horticulturally unfavorable characters. M. sieversii, now thought to be the primary progenitor of M. × domestica, grows wild in many diverse habitats in Central Asia and can have fruit quality comparable to commercial cultivars. Since 1989, four major collections of M. sieversii have been made in Central Asia, where scab is endemic. Some seed collections have been made from trees with superior fruit, that were not infected with scab. Over a 6-year period, 3000 seedlings from 220 wild M. sieversii trees representing 10 diverse ecosystems in Kazakstan, Uzbekistan, Kyrgyzstan, and Tajikistan have been inoculated with conidia of five races and two wild types of V. inaequalis. Suspensions (270,000 conidia/ml) were applied to 4- to 8-leaved seedlings, which were incubated for 48 h at 19°C with constant leaf wetness. Symptoms for three resistant reactions were assessed 2 to 4 weeks after inoculation: A = chlorosis with crinkling (Vf type reaction); B = stellate necrotic lesions (Vr type reaction), and N = large necrotic areas (uncharacterized resistant reaction). Results indicated that nearly 20% of the seedlings showed one or more of the resistant reactions. The range of resistance within seedling populations from each of the 220 single-tree sources ranged from 0% to 75%. Significant differences existed among seedlings from each of the ecosystems. Most resistance reactions appeared to be similar to those observed for Vr from “Russian seedling.” Resistant selections with superior horticultural traits may constitute a genepool for increased efficiency of breeding scab-resistant cvs. This genepool may also be useful to address the breakdown of resistance to V. inaequalis race 6.

scholarly journals Molecular Markers for the Scab Resistance (Vf) Region in Apple

1998 ◽  
Vol 123 (6) ◽  
pp. 992-996 ◽  
Author(s):  
Minou Hemmat ◽  
Norman F. Weeden ◽  
Herb S. Aldwinckle ◽  
Susan K. Brown
Keyword(s):  
Rapd Markers ◽  
Bulked Segregant Analysis ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Scab Resistance ◽  
Resistant Plant ◽  
Tight Linkage ◽  
Test Population ◽  
Rate Selection ◽  
Selection Of

Bulked segregant analysis was used to identify RAPD markers that display tight linkage to the Vf gene in apple (Malus sp.) that confers resistance to five races of apple scab [Venturia inaequalis (Cke.) Wint.]. We identified several new RAPD markers linked to Vf. The most tightly linked marker in the test population, S52500, was cloned and sequenced. A linkage map of the Vf region was developed using these markers, RAPD markers previously described by other laboratories, and the isozyme locus Pgm-1. An assay was developed for Vf by multiplexing the two markers closely flanking the Vf locus. This assay has a theoretical `escape' value (discarding a resistant plant) of 3% and an error rate (selection of a susceptible plant) of 0.02%.

scholarly journals The Rvi15 (Vr2) Apple Scab Resistance Locus Contains Three TIR-NBS-LRR Genes

2010 ◽  
Vol 23 (5) ◽  
pp. 608-617 ◽  
Author(s):  
Paolo Galli ◽  
Andrea Patocchi ◽  
Giovanni Antonio Lodovico Broggini ◽  
Cesare Gessler
Keyword(s):  
Venturia Inaequalis ◽  
Interleukin 1 ◽  
Apple Scab ◽  
Scab Resistance ◽  
Receptor Protein ◽  
Resistance Locus ◽  
Fresh Market ◽  
High Quality ◽  
Bac Clone ◽  
Bac Contig

Scab caused by the pathogen Venturia inaequalis is considered the most important fungal disease of cultivated apple (Malus × domestica Borkh.). In all, 16 monogenic resistances against scab have been found in different Malus spp. and some of them are currently used in apple breeding for scab-resistant cultivars. However, the self incompatibility and the long generation time of Malus spp. together with the high standards of fruit quality demanded from the fresh market render the breeding of high-quality cultivars in apple a long and expensive task. Therefore, the cloning of disease resistance genes and the use of the cloned genes for the transformation of high-quality apple cultivars could be an approach to solve these drawbacks. We report the construction of a bacterial artificial chromosome (BAC) contig spanning the Rvi15 (Vr2) apple scab resistance locus using two GMAL 2473 BAC libraries. A single BAC clone of the contig was sufficient to span the resistance locus. The BAC clone was completely sequenced, allowing identification of a sequence of 48.6 kb going from the two closest markers (ARGH17 and 77G20RP) bracketing Rvi15 (Vr2). Analysis of the 48.6-kb sequence revealed the presence of three putative genes characterized by a Toll and mammalian interleukin-1 receptor protein nucleotide-binding site leucine-rich repeat structure. All three genes were found to be transcribed.

scholarly journals Molecular Markers for the Scab Resistance (Vf) Region in Apple

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 855C-855 ◽  
Author(s):  
Minou Hemmat ◽  
Norman F. Weeden ◽  
Susan K. Brown
Keyword(s):  
Molecular Markers ◽  
Bulk Segregant Analysis ◽  
Rapd Markers ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Genetic Resistance ◽  
Scab Resistance ◽  
Tight Linkage ◽  
Commercially Important ◽  
The Relationship

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.

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

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.

scholarly journals Six promising selections from the Hungarian apple breeding program for multiple resistance

2005 ◽  
Vol 11 (3) ◽  
Author(s):  
M. Tóth
Keyword(s):  
Powdery Mildew ◽  
Fire Blight ◽  
Molecular Genetic ◽  
Apple Scab ◽  
Breeding Program ◽  
Scab Resistance ◽  
Multiple Resistance ◽  
Vf Gene ◽  
Apple Breeding ◽  
Malus Floribunda

An apple breeding program has been carried out at the Department of Fruit Science for more than a decade. Several apple selections have been released from the progenies of crosses in 1992 and 1993. Six candidates were submitted for national recognition out of the hybrids examined for more than a decade. The six selections are resistant against all the three most important apple diseases (apple scab, powdery mildew and fire blight). Scab resistance is controlled by the Vf gene originating from the species Malus floribunda 821 and transmitted by cultivar Prima. Heterozygote Vfvf genotype of the six cultivar candidates was proved by molecular genetic examinations of Dept. Genetics and Plant Breeding. Characteristics of these selections from 'Prima' progenies are shown on the base of our own observations.

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

HortScience ◽  
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.

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