A microscopic study of the different classes of symptoms coded by the Vf gene in apple for resistance to scab (Venturia inaequalis)

The growing of resistant apple varieties against the scab, impacts the Venturia inaequalis CKE. races development that can overcome the resistance. For this reason the main breeders object is to cumulate the different genetic mechanisms of resistance against this disease. Presented in this paper is the first genetic study of monosporic isolates in the Czech Republic. By means of RAPD and UPGMA methods which characterised the variability of 10 monosporic isolates from different localities and apple varieties. The monosporic isolate derived from the resistant genotype (Vf gene) proved a 79% genetic similarity with the isolate derived from sensitive variety Top Red. The genetic similarity of other isolates did not prove the dependence either on a locality or a host variety. The Vf and Vm genes accumulation in apple germplasm by means of specific PCR markers was studied. It was confirmed that Vf gene donors are always heterozygous. Concurrently it was statistically confirmed that the donor of Vm gene (OR-45-T-132) is heterozygous, too. The accumulation of Vf and Vm major genes against the scab was validated in 25% of seedlings of the cross.  

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Interaction between Venturia inaequalis and Apple Callus Tissue Cultures: an Electron Microscopic Study

Journal of Phytopathology ◽

10.1111/j.1439-0434.1986.tb00926.x ◽

1986 ◽

Vol 116 (4) ◽

pp. 315-322 ◽

Cited By ~ 9

Author(s):

I. Beech ◽

C. Gessler

Keyword(s):

Microscopic Study ◽

Electron Microscopic Study ◽

Callus Tissue ◽

Venturia Inaequalis ◽

Tissue Cultures ◽

Electron Microscopic

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MICROSCOPIC STUDY OF IN VITRO HOST-PATHOGEN RELATIONSHIPS BETWEEN APPLE AND VENTURIA INAEQUALIS.

Acta Horticulturae ◽

10.17660/actahortic.1997.447.94 ◽

1997 ◽

pp. 465-466

Author(s):

M. Chevalier ◽

J. Guillaumes ◽

I. Parisi ◽

F. Mourgues

Keyword(s):

Microscopic Study ◽

Venturia Inaequalis ◽

Host Pathogen

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Alleles controlling apple skin colour and incompatibility in new Czech apple varieties with different degrees of resistance against Venturia inaequalis CKE.

Plant Soil and Environment ◽

10.17221/3557-pse ◽

2011 ◽

Vol 51 (No. 2) ◽

pp. 65-73 ◽

Cited By ~ 5

Author(s):

M. Melounová ◽

P. Vejl ◽

P. Sedlák ◽

J. Blažek ◽

J. Zoufalá ◽

...

Keyword(s):

Molecular Level ◽

Venturia Inaequalis ◽

Field Resistance ◽

Skin Colour ◽

Vf Gene ◽

Apple Varieties ◽

New Findings ◽

S Alleles ◽

Allele Specific ◽

S Allele

The skin colour of 21 varieties was assessed on a molecular level. Four varieties had yellow skin colour with the genotype constitution a1a1, a1a2 or a2a2. Seventeen varieties had dominant red colour. Homozygous A1A1 constitution was present in 7 varieties, and heterozygous constitution A1a1 or A1a2 was found in the rest of the assessed varieties. The S-alleles controlled the incompatibility system of the pistil. Their detection is possible by means of the PCR method on the basis of allele specific primers. Six S-alleles (S1, S2, S3, S5, S7 and S9) were studied in the same collection of 21 diploid Czech varieties. This paper brings new findings on S-allele characterization, because the Czech varieties have not yet been studied on a molecular level. Both types of S-allele were found in 12 varieties. Only one type of S-allele was described in 9 varieties. Simultaneously, the presence of the Vf gene was screened in the collection of 21 Czech apple varieties. Ten varieties with a field resistance against the scab had a heterozygous constitution of the Vf gene. All 11 susceptible varieties were recessive homozygous vfvf.

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

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Horticulture ◽

10.15835/buasvmcn-hort:2021.0022 ◽

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.

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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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