Surveying viruses on ornamental trees and shrubs in two Hungarian botanical gardens and an arboretum

In Hungary the most common disease of fruit trees causing the most severe damages is Plum pox virus (PPV). This is why it is important to know other woody host plants that can be considered as source of infection. National surveys have been carried out since 2002 for revealing the distribution of PPV on ornamental and wild Prunus species.From 2005 this work has been extended to studying other viruses on other woody plants. In two botanical gardens and an arboretum we selected plants (species and varieties) showing virus symptoms among various thousands of woody plants and submitted them to indexing on woody and herbaceous indicators, as well as to testing with ELISA for the presence of the following 11 viruses occurring on woody plants: PPV, Prune dwarf virus (PDV), Prunus necrotic ringspot virus (PNRSV), Cherry leafroll virus (CLRV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), Apple mosaic virus (ApMV), Apple chlorotic leafspot virus (ACLSV), Strawberry latent ringspot virus (SLRV), Tomato black ring virus (TBRV) and Arabis mosaic virus (ArMV).Up to now, in 28 plant species and varieties, PPV, PDV, PNRSV, CLRV and ASPV have been detected so far. The presence of PPV was found in 9 species/varieties, such as Prunus cerasifera ’Pendula’, P. cerasifera ’Pissardii’, P. glandulosa, P. glandulosa ‘Alba Plena’, P. glandulosa ’Sinensis’, P. japonica, P. sogdiana, P. tomentosa (from Tibet) and P. x blireana.Seventeen species/varieties were found to be infected with PDV: Lonicera caucasica, L. maackii, L. sachalinensis, Prunus mume ’Omoi-no-mama’, P. salicina (from China), P. spinosa ’Plena’, P. spinosa ’Purpurea’, P. serrulata ’Amanogawa’, P. serrulata ’Ichiyo’, P. serrulata ’Pink Perfection’, P. serrulata ’Taihaku’, P. serrulata ’Yedo-sakura’, P. subhirtella ’Plena’, P. tenella, P. yedoensis, P. yedoensis ’Moerheimii’ and Syringa yunnanensis. Certain species/varieties infected with PDV were positive also for CLRV, such as P. spinosa ’Purpurea’, P. yedoensis, P. yedoensis ’Moerheimii’, P. subhirtella ’Plena’, P. serrulata ’Yedo-sakura’ and to ASPV: P. subhirtella ’Plena’ and P. serrulata ’Yedo-sakura’. PNRSV was detected in P. cerasifera ’ Nigra ’ and ’Hollywood’. The difference of symptoms provoked by PDV on herbaceous hosts suggests that various strains of this virus affect hosts, mainly yellow mottle disease described as a separate strain by Ramaswamy and Posnette on ornamental cherries in 1972. Molecular studies are in progress to confirm the above results. Keywords: ornamental trees and shrubs, virus symptoms, ELISA, Prunus, Lonicera, Syring

Detection and identification of phytoplasmas in peach based on woody indexing and molecular methods

Symptoms resembling phytoplasma disease have been observed on peach trees in a seed-source plantation of stone fruits in south Hungary quite recently. In this publication we report on the results of woody indexing of symptomatic peach trees on GF 305 indicator in the field and under greenhouse conditions as well as on molecular studies. Phytoplasma infection detected on GF 305 indicators in greenhouse and field indexing was confirmed by PCR. Nested PCR was conducted using universal primer pairs followed by group and subgroup specific primers for the second amplification. RFLP analysis of nested PCR products was performed using Rsal restriction enzyme. Based on the results of molecular studies it can be concluded that phytoplasmas, belonging to the European stone fruit yellows subgroup (16SrX-B) were identified in peach trees. Further studies on symptomatic peach trees originating from different parts of Hungary are in progress