scholarly journals Molecular Screening of Some Apple Progenies for Detection Vf Gene Using Marker Assisted Selection

2021 ◽  
Vol 78 (2) ◽  
pp. 36
Author(s):  
Georgeta BIVOLARIU (GUZU) ◽  
Ioan ZAGRAI ◽  
Luminița ZAGRAI ◽  
Mirela Irina CORDEA ◽  
Claudiu MOLDOVAN
Keyword(s):  
Resistance Gene ◽  
Fruit Quality ◽  
Marker Assisted Selection ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Molecular Screening ◽  
Breeding Programs ◽  
Vf Gene ◽  
Local Variety ◽  
Malus Floribunda

Apple scab, caused by Venturia inaequalis is one of the most damaging pathogens that affects apple species. Cross combinations were made between Auriu de Bistrița cv. (female genitor) - a valuable local variety in terms of fruit quality but only tolerant to scab, and Florina cv. (male genitor) used as a donor of Vf resistance gene. It was first detected in Malus floribunda Clone 821, which was later transferred to commercial varieties by different breeding programs. To confirm the presence of Vf gene, progenies resulting from the mentioned combination were tested with MAS (Marker Assited Selection), using two dominant primers pairs (AM19, U1400), and another one codominant (AL07) used to distinguish homozygous and heterozygous genotypes. After the crossing combination, a number of twenty-six hybrids were obtained, of which 50% (13 hybrids) were clasified as resistant (heterozygous), respectively 50% (13 hybrids) as susceptible (recessive homozygotes), so the Mendelian ratio was confirmed.

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

2004 ◽  
Vol 94 (4) ◽  
pp. 364-369 ◽  
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.

scholarly journals Effect of late summer treatments by strobilurines on storage diseases of apples

2006 ◽  
Vol 54 (4) ◽  
pp. 39-44 ◽  
Author(s):  
Pavel Minář
Keyword(s):  
Czech Republic ◽  
Fruit Quality ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Field Tests ◽  
Late Summer ◽  
The Czech Republic ◽  
Storage Diseases ◽  
Biological Efficacy ◽  
Weight Decrease

Biological efficacy of strobilurines (trifloxystrobin and kresoxim-methyl) was evaluated to compare the effect of late treatments of apples against post-harvest diseases with the effect of widely used reference products (captan, tolylfluanid, dithianone, dodine). One treatment 3–4 weeks before the harvest was applied (1000 l/ha water). Tested and reference products were used in doses authorised in the Czech Republic against the apple scab (Venturia inaequalis). Strobilurines effectiveness overcame all the products compared and showed an effect on reduction of weight decrease during the storage. In total 8 field tests were performed in 2000–2004 were efficacy, effect on fruit quality and weight decrease during storage was assessed.

scholarly journals 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

2004 ◽  
Vol 94 (4) ◽  
pp. 370-379 ◽  
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.

AN UPDATED GENETIC MAP AROUND THE VF GENE FOR RESISTANCE TO APPLE SCAB AND MARKER ASSISTED SELECTION FOR RESISTANCE

1998 ◽  
pp. 481-486
Author(s):  
S. Gardiner ◽  
V. Bus ◽  
H. Bassett ◽  
A. White ◽  
D. Noiton ◽  
...  
Keyword(s):  
Genetic Map ◽  
Marker Assisted Selection ◽  
Apple Scab ◽  
Vf Gene ◽  
Selection For

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 510 Impact of a Reduced Fungicide Program on `Liberty' Apple Tree Vigor, Productivity, and Fruit Quality

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 482E-482
Author(s):  
L.P. Berkett ◽  
M.E. Garcia ◽  
J. Clements ◽  
G. Neff
Keyword(s):  
Fruit Quality ◽  
Apple Tree ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Quality Data ◽  
Apple Cultivars ◽  
Show Difference ◽  
Repeated Applications ◽  
Marketable Fruit ◽  
Important Disease

Apple scab, a fungal disease caused by Venturia inaequalis, is considered the most important disease of apple worldwide. The disease can be devastating, causing reduction in yield or making the apples unfit for the market. Currently, the production of marketable fruit from scab susceptible cultivars depends on the repeated applications of fungicides. Scab-resistant apple cultivars, which are genetically immune to apple scab, can offer a biological alternative to fungicide use. `Liberty,' was bred for immunity to apple scab; however, it is not immune to other apple diseases and pests. Research has been conducted during a 3-year project (1996–1998) to determine whether reduced fungicide programs adversely affect overall tree vigor, productivity, and fruit quality. Data collected include tree vigor (TCSA and time of leaf abscission), tree productivity (YE), and fruit quality (fruit firmness and disorders during storage). Results indicate no significant differences between the two treatments (reduced fungicide and no fungicide application) in most of the parameters measured. Based on fruit that were harvested and graded to commercial standards, the estimated gross monetary value of the crop does not show difference between treatments. These results could translate into an economic advantage for growers when one factors in the savings in fungicide purchases. In addition, there are also health and environmental advantages to reduced fungicide usage.

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