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Ion L.,University of Bucharest | Hoza D.,University of Bucharest | Asanica A.,University of Bucharest | Neagu T.,University of Bucharest | And 2 more authors.
Acta Horticulturae | Year: 2013

Apple scab, Venturia inaequalis (Cke) Wint., is a major problem in Romanian apple orchards and is responsible for serious economic losses. The purchase of spraying equipment and phytopharmaceutical products is very expensive in comparison to the income of local apple growers. This is one of the reasons why reduced fungicide sprayings are becoming more and more important. Current disease control is achieved mainly through scheduled applications of fungicides. The Venturia inaequalis is an aggressive pathogen difficult to control once it is established in an orchard. Because a chemical control is so difficult, it was desirable to promote the breeding of cultivars resistant to this pathogen. Prospecting through Romanian apples collections has leaded us to the discovery of several sources of resistance to Venturia inaequalis. The different columnar or spur apple varieties were chosen among the different sources of resistance as it could also be used to develop a valuables resistant variety. This new program was started in spring 2010. The artificial inoculation in the greenhouse was performed with race 6 on trees of Malus floribunda 821. A large variation in resistance and (or) susceptibility was observed among the individuals of the progeny. The breeding of apple cultivars resistant to Venturia inaequalis could be much improved by marker-assisted selection. A molecular marker closely linked to the resistance locus called Vf could replace selection based on infection studies. To find such molecular markers, DNA of progenies from crossings of a resistant and a susceptible apple tree will be subject to bulked segregant analysis.

Zagrai I.,Fruit Research and Development Station Bistrita | Zagrai L.,Fruit Research and Development Station Bistrita | Festila A.,Fruit Research and Development Station Bistrita | Baias I.,Fruit Research and Development Station Bistrita | And 3 more authors.
Acta Horticulturae | Year: 2013

A certification program focused on plum was established at Fruit Research & Development Station Bistrita, Romania started with 2008. The objective was to obtain in the first step the prebasic material and, subsequently, to establish plum mother plantations with basic material satisfying the EPPO recommended certification standards. Fifteen plum (Prunus domestica) cultivars ('Iulia', 'Matilda', 'Geta', 'Zamfira', 'Ivan', 'Dani', 'Doina', 'Romaner', 'Elena', 'Jubileu 50', 'Flora', 'Renclod d'Althan', 'Stanley', 'Anna Späth' and 'Carpatin') were subjected to this work. Selected plum trees from experimental orchards were monitored and tested for pathogens listed in EPPO standards. One shoot was then collected from each candidate and tested before grafting onto virus-free 'Myrobolan 29C' rootstock. Selected clones were also tested on woody indicators 'GF 305'. Propagated material was individually tested one year later. The fifteen cultivars were found virus free both before and after propagation. Consequently, the propagated material was certified as 'Prebasic category' and preserved to the nuclear-stock collection. Scions of ten plum cultivars ('Iulia', 'Matilda', 'Geta', 'Zamfira', 'Ivan', 'Romaner', 'Elena', 'Renclod d'Althan', 'Stanley', 'Anna Späth') from prebasic material were used to produce 'Basic category' by grafting onto virus-free 'Myrobolan 29C' rootstock. Propagated plants were individually tested during the vegetative period. All tests (in both steps to obtain prebasic and basic category, respectively) were done according to the EPPO recommendations. DAS-ELISA was used for Plum pox virus (PPV), Prune dwarf virus (PDV), Prunus necrotic ringspot virus (PNRSV), Apple chlorotic leaf spot virus (ACLSV), Apple mosaic virus (ApMV) and Myrobalan latent ringspot virus (MLRSV). To increase the sensitivity of PPV and PDV detection, IC-RT-PCR was performed. Nested-PCR method was made to detect 'Candidatus Phytoplasma prunorum' that cause European stone fruit yellows (ESFY). The results obtained allowed to certify 90 plants of the fifteen cultivars (6 plants/cultivar) as 'Prebasic category' in the first step, and 93 plants of the ten cultivars as 'Basic category' in the second step.

Ion L.,University of Bucharest | Hoza D.,University of Bucharest | Moale C.,Fruit Research and Development Station | Petrica A.M.,University of Bucharest | And 4 more authors.
Acta Horticulturae | Year: 2011

Sharka, caused by Plum pox virus (PPV), is the most devastating viral disease affecting stone fruit crops in Europe. It causes important economic losses in the fruit production, mainly in apricot and European plum. The spreading of PPV might be limited by planting PPV resistant or at least less-susceptible rootstocks on which PPV resistant scions have been grafted. In spring 2008, at USAMV Bucharest, Romania, a breeding program aiming to develop cultivars and rootstocks resistant to PPV was initiated and an efficient procedure for the determination of sharka resistance within the progenies was established. It is based on the methodology developed at IVIA Valencia, Spain. Peach 'GF305' rootstocks were used as indicators for susceptibility to PPV in comparison with the Myrobolan BN 4 Kr considered as resistant to sharka (Minoiu et al., 2002; Zagrai et al., 2009). The subsequent grafting protocol was optimized, and a Romanian PPV-D isolate was identified and used as inoculums source. The two rootstocks were grafted with apricot individuals originating from crossing between a PPV resistant genitor (e.g., 'SEO', 'NJA2') and Romanian preferred cultivars. Grafted plants were inoculated by chip-budding and monitored by visual inspection and ELISA, completed by IC/RT-PCR for the PPV negative plants. Preliminary data of the Romanian PPV resistance breeding programs will be presented.

Stanica F.,University of Bucharest | Platon I.,Fruit Research and Development Station
Acta Horticulturae | Year: 2011

With the aim of testing and promoting new planting systems at the Faculty of Horticulture in Bucuresti, a trial was organized with some of most common apple cultivars in the Romanian orchards: 'Florina', 'Idared' and 'Aura', a new scab resistant Romanian cultivar. Trees were grafted on M.9 and M.26 rootstocks and planted in the spring 2005 at 3.5 m between rows. The in-row tree spacing varied from 1.0 m for M.9 to 1.5 m for M.26 for Spindle and from 1.5 m for M.9 to 2.0 m for M.26, for Drilling and Mikado canopies. Sod middles were utilized between rows and a polypropylene fabric was uses under the trees as a mulch. Insects and diseases were controlled utilizing an Integrated Pest Management program. The canopy formation consisted of summer pruning and tying down shoots. The formation of the flowering shoots was positively influenced by M.9 rootstock in all cultivars. There were no significant differences between rootstocks and vegetative shoot formation. The highest number of total flowering shoots was obtained with 'Idared' in the Drilling and Mikado canopy systems. M.26 rootstock had the largest vegetative growth e×pressed as total shoot length, average shoot length and total shoot number. One e×ception was M.9 rootstock in the Mikado canopy. 'Aura' was the most vigorous cultivar. The three cultivars had different growth habits related to the canopy and rootstock used. The highest yield was obtained on M.9 rootstock with Mikado canopy.

Zagrai I.,Fruit Research and Development Station | Zagrai L.,Fruit Research and Development Station | Butac M.,Romanian Research Institute for Fruit Growing
Acta Horticulturae | Year: 2015

The use of resistant cultivars is considered to be the most efficient solution to control Plum pox virus (PPV). The identification of new potential sources of PPV resistance in plum germplasm remains important for the future development of new cultivars due to the paucity of naturally occurring resistance reported so far. Two plum selections named 'Local de Dragasani' and 'Dunarea albastra' respectively, grown within the experimental plum orchard with high inoculum pressure with PPV-D and PPV-Rec strains, have remained PPV free during a period of 17 years. When artificially inoculated in greenhouse conditions with PPV-D or PPV-Rec, a typical hypersensitivity response was observed on 'Local de Dragasani'. Because the effectiveness of hypersensitivity against PPV is still under controversy, additional studies are requested. The behavior of 'Dunarea albastra' under high natural inoculum pressure with PPV also showed a particular interest. Is this selection a potential candidate for PPV resistance? Artificial inoculation needs to be performed to obtain pertinent conclusions. Studies on resistance to PPV of the two plum selections are going to be expanded.

Zagrai I.,Fruit Research and Development Station | Zagrai L.,Fruit Research and Development Station | Preda S.,Fruit Research and Development Station | Kelemen B.,Babes - Bolyai University | And 4 more authors.
Romanian Biotechnological Letters | Year: 2010

Plum pox virus (PPV) is considered the most devastating viral pathogen of stone fruits causing serious yield losses. Although PPV is endemic in Romania, limited data about the occurrence of its strains in some plum regions like Muntenia are available. Considering this fact, fifty PPV isolates collected from five different commercial plum orchards from Muntenia were investigated. PPV detection was made by DAS-ELISA and by IC-RT-PCR. PPV strains were serologically determined by TAS-ELISA using PPV-D and PPV-M specific monoclonal antibodies. Molecular strain typing was done by IC/RTPCR targeting three genomic regions corresponding to (Cter)CP, (Cter)NIb/(Nter)CP and CI. RFLP analysis at the C-ter of CP cistron was used to distinguish the two major strains, D and M based on a RsaI polymorphism located in this genomic section. All PCR products targeting (Cter)CP and two PCR product spanning the (Cter)NIb/(Nter)CP were sequenced. All PPV isolates typed as PPV-M by serological analysis and by molecular differentiation in the genomic region corresponding to (C-ter)CP proved to be PPV recombinant (PPV-Rec) when the molecular analysis were performed in the region corresponding to NIb/CP. Sequencing results confirmed a high similarity with different sequences of PPV-Rec previously reported. Overall results provided that in Muntenia the prevalent strain is PPV-D. PPV-Rec is also present with a much lower frequency both in singular and mixed infections (PPV-D+PPV-Rec). © 2010 University of Bucharest.

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