IMPLEMENTATION OF CERTIFICATION STANDARDS FOR OBTAINING NUCLEAR-STOCK PLUM MATERIAL IN ROMANIA

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.