Several viruses are known to infect stone fruit trees and cause serious problems in their cultivation; hence, it is essential to use virus-free and healthy propagation material to establish a plantation. As stone fruit trees are propagated vegetatively, both the scion and the rootstock should be pathogen-free. The traditional method for plant virus eradication is meristem culture after in vivo thermotherapy. Prunus species are extremely sensitive to high temperature and have low regeneration capacity from meristem explants which makes it difficult to apply the conventional method. To avoid the application of meristem culture it has become necessary to search for additional methods. The most widespread elimination methods are based on in vitro shoot cultures. It is a challenge to find an optimal method with high efficacy in virus elimination that has little harmful effect on plantlets. In the present study, we collected the elements of current knowledge about viruses and viroids that are able to infect Prunus species and reviewed recent methods that have been used efficiently to eliminate them from Prunus species, applying thermotherapy alone or in combination with shoot tip excision, chemotherapy, cryotherapy or electrotherapy. The key factors influencing the effectivity of virus elimination procedure and in vitro culture survival are also discussed.

The interest in hazelnut (Corylus avellana L.) cultivation has recently increased in Hungary, it is currently grown on 490 hectares. In August 2021 early powdery mildew symptoms were observed in a ...

Sour cherry is one of the most important horticultural crops in the Hungarian market. Its flavour combination makes it ideal for fresh consumption as well as canned products. The Hungarian and European markets have requested for new varieties to be introduced, making the evaluation of breeding and prebreeding material a crucial point. A total of 30 sour cherry accessions from the genebank collection were investigated for their potential inclusion into the breeding program. The main aim of the study was to identify candidates for future breeding programs, selecting their colour profiling and total polyphenolic content (TPC). This study follows the antioxidant activity of cherry species by determining the total content in polyphenols. Polyphenols are found in higher concentration in cherries when compared to other plants and have been identified as free radical scavengers, which are useful to prevent the occurrence of several diseases. Furthermore, TPC has been observed as a contributor of bitterness, acidity, colour, flavour, odour, and oxidative stability. The accessions were evaluated for their colour, fruit weight, flavour profile, firmness, and TPC. Colorimetric data were compared among four methods to illustrate to the Hungarian breeders which of the available approaches is the most accurate for sour cherry breeding. Results suggested that several accessions appear relevant for the breeding program, such as ‘Pipacs 1′, ‘Bosnyák’, ‘Hortenzia Királynője’, and ‘Mogyoródi Kései’. The total polyphenolic content was highest in ‘Pipacs1′ and lowest in ‘Kántorjánosi 3′. ‘Pipacs 1′ and ‘Hortenzia Királynője’ had interestingly high acidity content and light to very light fruit colours. ‘Bosnyák’ had a deep and dark colour with high soluble sugar content. ‘Mogyoródi Kései’ appears to have the biggest fruit. All mentioned varieties will be included in future breeding programs.

Cherry virus A, a capillovirus, can infect different Prunus species and be present as a latent infection in orchards. CVA infection was detected in a Hungarian stock collection of Prunus domestica ‘Besztercei Bt. 2’. In our study, different in vitro virus elimination techniques (thermotherapy combined with shoot tip culture and chemotherapy alone or combined with thermotherapy) were used and compared for their efficiency in eliminating CVA from ‘Besztercei Bt. 2’ plum cultivar. Thermotherapy was carried out at 38/36°C (day/night) in a heat chamber followed by the excision of 1–2 mm long shoot tips for plant regeneration. As a chemotherapy agent, ribavirin or zidovudine was added to the multiplication medium at two different concentrations with or without two weeks of thermotherapy pretreatment. The plum shoots tolerated 14–18 days of heat treatment, 64% of the plants regenerated from shoot tips, and 75% of the tested regenerated plants were confirmed by RT‒PCR to be CVA-free. Ribavirin and zidovudine did not negatively affect the survival of the plum shoots at any applied concentrations. Zidovudine alone was not able to efficiently eradicate virus from the treated plantlets, but when zidovudine was combined with heat treatment, the number of CVA-positive plants decreased to 60%. In contrast, ribavirin alone was very efficient at eliminating CVA from all the tested plants when used at a concentration of 25 mg L^− 1. To our knowledge, this is the first report of eliminating CVA from Prunus sp. via in vitro techniques.