Vol 11, No 3 (2005)

Published August 12, 2005

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Articles

Exploring and preserving old apple cultivars of the Carpathian basin
9-13.

In a few scattered orchards of the Carpathian basin one can still find our most common historical apple cultivars and certain traces of traditional cultivation. We consider it an important part of the Department's breeding work to explore old apple cultivars which can be used as parent partners and sources of resistance, to identify them pomolo...gically as well as to examine the production and marketing value of old cultivars recommended for cultivation in ecological production and in gardens. This paper documents the results of expedition and collecting work carried out in three regions of the Carpathian basin (foot of the Carpathian Mountains, Transylvania, Aggtelek karst area), and also the saving of old Hungarian apple cultivars preserved until present in the English National Fruit Collection. A total of more than 100 old apple cultivars and variations, as well as 13 valuable genotypes were collected during our explorations in the above mentioned four areas. A further aim of our work is to contribute to the protection of still savable archaic fruit production relict= areas and to the preservation of cultivars in the certain regions, and also to promote the recognition of the aesthetic landscape value of old apple trees and endemic orchards of old cultivars. Our good co-operating partners in this work are Aggtelek National Park, Farmer Club of Visk and the consultation centre of Hungarian horticulturist training beyond the border in Nyárádszereda.

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Evaluation of fruit quality of old apple cultivars originating from the foot of the Carpathian Mountains, for utilization in breeding and in organic farming
15-24.

In the frame of the apple breeding program at the Department of Fruit Science old cultivars found in the Carpathian basin were involved in examination as well. Beside testing susceptibility to fire blight (Erwinia amylovora of old genotypes (historical, local and regional cultivars) originating from scattered orchards of Visk (foot of ...the Carpathian Mountains), fruit quality was also evaluated and other open-field observations were made.

According to the results of inner content examinations, 'Szemes alma' and 'Sikulai alma', chosen as gene sources for breeding to resistance against fire blight, had inner content values worthy to mention in some aspects, and competing with those of the control cultivar 'Jonathan'. The quality of 'Pónyik alma', also recommended as a gene source is confirmed by the data of earlier literature. Further three cultivars ('Batul', 'Vilmos renet', 'Zöld sóvári') also proved to be good based on resistance against Erwinia amylovora, the first two cultivars are suitable from the point of view of fruit quality, too.

In our field observations, susceptibility to apple scab and powdery mildew was evaluated. Among cultivars selected from the foot of the Carpathian Mountains on the base of resistance against Erwinia amylovora, the production value of 'Szemes alma' is worsened by its high susceptibility to apple scab. Further selected cultivars ('Sikulai', 'Pónyik alma', 'Batul', 'Vilmos renet') are not too susceptible to fungal diseases and their fruit quality is also suitable, therefore they can be recommended for direct planting in ecological farming or in restoring scattered orchards.

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Six promising selections from the Hungarian apple breeding program for multiple resistance
23-28.

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.

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Pomology of gene resources bearing resistance to Erwinia amylovora
29-33.

The ecological farming and an increasing demand for healthy fruits free from chemical residuals necessitated the reevaluation of the existing cultivars and breeding suitable cultivars for the new requirements. We have gathered the old genotypes known in the Carpathian Basin, and we have selected the most suitable ones according to fruit quality... and resistance to diseases in the last fifteen years. The main aim was the selection of resistant genotypes against fire blight and powdery mildew as gene sources for our breeding program. On the other hand, we consider the best quality traditional cultivars as extensive landscape elements (wayside tree rows or extensive squash producing plantations).

During the pathological evaluation 'Szemes alma', 'Pónyik', 'Sikulai', 'Tordai piros 'cavil' and 'Szabadkai szercsika' cultivars proved to be good resistance sources (due to their outstanding resistance to fire blight). The latter four cultivars are not susceptible even to fungal diseases, and their quality is also acceptable so those are commendable for ecological farming or for renewing the sparse orchards. According to fruit quality and low susceptibility to diseases 'Batul' and 'Vilmos renet' can also be offered for extensive organic production.

We have made original or renewed pomological descriptions of the selected cultivars, and we also publish their characters according to the terms of UPOV TG/14/8 based on to our evaluations.

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Fire blight (Erwinia amylovora) susceptibility of old Hungarian apple cultivars
35-38.

The aim of the Hungarian apple breeding program started in the Department of Fruit Science was to find resistant apple cultivars against major diseases (scab, powdery mildew, fire blight). The outbreak of fire blight (Erwinia amylovora) in 1996 motivated us to search new resistant sources principally from old traditional apple cultivar...s. First of all, cultivars have been gathered since 1997 from Carpathia (Visk) and evaluated between 2001 and 2003. In this recent study evaluation of resistance of old Hungarian genotypes to fire blight collected from the English National Fruit Collection (Brogdale, Faversham) is presented.

13 old Hungarian apple cultivars in 2002, and 38 genotypes in 2005 have been evaluated. We used `Idared' and 'Jonathan M41' as susceptible controls and 'Liberty' and 'Remo' as resistant ones. Shoots of two-year-old potted plants were inoculated with a mixture of virulent E. amylovora isolates (Ea2, Ea60, Ea67) at a concentration of 5 x 108 cells/ml. Resistance of apple cultivars was evaluated weekly, four times after inoculation by disease severity of symptoms. Numbers of bacterial colonies in 1 cm length shoot were determined in the fourth week after infection.

8 cultivars in 2002 and 9 cultivars in 2005 displayed notable resistance to fire blight based on one-year data. Based on the coincident data of both years, out of the cultivars collected also from Carpathia ‘Pónyik', and `Sikulai' were found to be resistant and gene sources additional old Hungarian valuable apple genotypes could be selected: `Szabadkai szercsika' and `Tordai piros !davit'. The cultivar `Szemes alma' originated from Visk has proved to be recurrently resistant.

The number of bacterial cells in shoots of the investigated cultivars correlated with the severity of symptoms. With this method, which was introduced by us earlier, we can screen cultivars displaying weak visible symptoms, which cannot be proposed as a source of resistance because of their latent infection.

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The inheritance and durability of scab resistance in apple progenies
39-46.

In order to select the appropriate parent cultivars and maintain the durability of resistance, it is important to clarify the mechanisms of inheritance of scab resistance depending on the parents. It has been known that the progeny segregation ratios based on scab-resistance do not depend only on the genotype of the resistance locus but also on... the genetical makeup of the donor and recipient parents as well as on the susceptible parent.

The aim of this study has been to demonstrate what factors in the Vf, Vr and VA scab-resistant cultivars — combined with susceptible and resistant parents — affect the inheritance and durability of resistance in seedlings in their first 4 year's growing four years' growth. After inoculating apple seedlings sown in 2001 with the suspension of Venturia inaequalis (Cke.) Wint. in the greenhouse, we studied the segregation ratios of the progenies into reaction classes. Seedlings showing resistance in the greenhouse were also evaluated for scab-resistance after they had been moved to the field and had naturally been infected with the pathogen in 2002 and 2004.

The majority of our results obtained in the greenhouse test, similarly to earlier experiences, have not justified monogenic inheritance at the phenotypic level. The effect of susceptible parent cultivars on the segregation ratio of progenies have become apparent again. The high infection rate of seedlings in the field trials, which had previously exhibited varying degrees of resistance in the greenhouse test, has raised concern. Our data has raised further doubts, concerning the durability of Vf resistance in Hungary. It is assumed that the composition of natural field populations of Venturia inaequalis in Szigetcsép has changed. The complexity of Vf resistance has been confirmed. The high infection rate in the progenies derived from Vf resistant cultivars draws the attention to the importance of utilizing additional sources of resistance.

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Metaxenic pollen effect of scab resistant apple cultivars on the fruit of apple
47-52.

As a part of an apple breeding program, we have examined the pollen effect on the fruit appearance and inner quality of different apple cultivars in the Corvinus University of Budapest Department of Fruit Science. Five apple cultivars ('Golden Reinders', 'Regal Prince', 'Rewena', 'Renora', 'Idared') have been crossed by the pollen of some new a...nd some traditional cultivars in our experiment. The measurements were carried out in the analytic and fruit examining laboratory of the Department of Fruit Science. The diameter, height and stem length were measured by digital caliper. We have also examined the squash ratio, soluble solid- and acidic content. Sugar content was calculated by a schedule released by the International Sugar Committee (ISC). From the sugar- and acidic content, we could also count the Pomona-value.

We have observed interesting effects according to some attributes in some crossing combinations with the help of statistical analysis. Crossing 'Golden Delicious' with 'Freedom', 'Prima', and 'Baujade' have resulted in smaller fruit size than other combinations. No significant differences could be observed on `Golden Reinders' fruits according to metaxenic coloration in the year of the examination. On the other hand the color modifying effect of pollen donating cultivars have manifested on the red fruits of 'Regal Prince' (Gala Must). `Freedom' as a pollen donating cultivar has resulted outstanding value in our consistency measurements. Squash ratio was the highest in combinations pollinated by 'Prima' and `Reglindis'. We have noticed balanced values when measuring inner qualities, only `Reka' has caused lower acidic content. Significant differences have been found in combinations according to the number of frivolous seeds. No frivolous seeds were found in the combinations 'Golden Reinders' x 'Freedom' and 'Idared' x 'Prima'. Almost two frivolous seeds were found in the fruits of the combination 'Renora' x 'Sóvári' in average.

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Anatomical study of the leaves and petioles of scab resistant and susceptible apple cultivars
53-57.

Anatomic studies have been performed on the leaf blade, petiole and annual shoot on six apple cultivars by means of scanning electron as well as light microscope. Four of the cultivars examined are resistant to scab (Florina, Freedom, MR-10, MR-11), whereas two of them are susceptible (Jonathan and Idared). Preliminary results suggest that diff...erences in the width of cross sections of leaf blades, in hairyness, in the shape and size of epidermal cells, moreover, in the cross sections of petioles and shoots are considerable. Some of the anatomical properties seem to be correlated with scab resistance or susceptility of the respective cultivars. Therefore, further studies extending to other cultivars may corroborate our claims to find causal relations between anatomical traits of the leaves and disease, especially scab resistance of apple cultivars.

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Application of DNA markers for detection of scab resistant apple cultivars and selections
59-63.

A DNA marker-based study was undertaken to identify the occurrence of major scab resistance genes in some apple cultivars and selections of importance for apple breeding. Unfortunately none of the RAPD-based markers previously reported to detect the Va, Vb, Vr and Vx genes produced unambiguous results.... By contrast, the CAPS marker MI8 produced the expected three bands in all cultivars and selections already known or suspected to have the Vf gene, as well as in the Russian cultivar 'Antonovka Polotora Funtovaja' suspected to have Va resistance which however may be allelic to Vf. Vf-carrying selections and newly named cultivars 'Frida' and 'Fredrik' are grown successfully in Sweden without fungicides, suggesting that the Vr resistance breaking scab races 6 and 7 have not yet become a problem. The SCAR marker B12 detected the Vm gene in 'Prairifire', 'Rouville', clones 'OR45T132' and 'OR48T70', and selection '16-36-193'. The SSR locus 0102b10 detected one band at 118 by in 'Reka'. This is presumed to be identical to the Vr gene marker previously reported.

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