Typing and distribution of Plum pox virus isolates in Romania

Plum pox or Sharka, caused by Plum pox virus (PPV) is considered the most destructive disease of plum. Although PPV is widespread in all plum growing areas of Romania and causes serious yield losses, little is known about the variability of its isolates at a country level. For this reason, a large-scale study was performed with the aim of obtaining a picture of the prevalence and distribution of PPV strains in plum. During a three year survey, 200 PPV isolates collected from 23 different plum orchards from Transylvania, Moldavia and Muntenia areas were investigated. DASELISA and IC-RT-PCR were used for PPV detection. PPV strains were serologically determined by TAS-ELISA using PPV-D and PPV-M specific monoclonal antibodies. Molecular strain typing was done by IC/RT-PCR targeting three genomic regions corresponding to (Cter)CP, (Cter)NIb/(Nter)CP and CI. RFLP analysis was used to distinguish D and M strains, based on the RsaI polymorphism located in (Cter)CP. To confirm the presence of PPV-Rec strain, 13 PCR products spanning the (Cter)NIb/(Nter)CP were sequenced. Overall results showed that in Romania the predominant strain is PPV-D (73%), followed, with a much lower frequency, by PPV-Rec (14%). Mixed infections (PPV-D+PPVRec), which might generate additional variation by recombination, are also frequent (13%).Keywords: Romania, PPV strains, DAS/TAS-ELISA, IC/RT-PCR, RFLP, sequencin

The behaviour of some plum cultivars to brown rot fruit infection in northern Transylvania

The plum tree (Prunus domestica L.) is the dominant fruit tree species in Romania, according to the FAOSTAT (2021) data base. Globally, Romania ranks the second place after China at the top of major plum growing countries. This species is susceptible to various economically impactful diseases such as brown rot, produced by Monilinia spp. Climatic conditions have an important role in the occurrence and frequency of disease damage depending of a cultivar. Therefore, in 2023 at the FRDS Bistrita, was monitored the behaviour of brown rot damage on 18 plum cultivars with different ripening periods. During the growing stage, 12 conventional phytosanitary treatments were applied up to the harvest time. The determinations were made in the field after fruit harvesting, at the consumer's ripeness stage. Expectedly, the response to brown rot infection on fruits was different through all the cultivars studied. The results revealed low infections with Monilinia spp. on ‘Zamfira’ (6.9%), ‘Anna Späth’ (7.0%), and ‘Doina’ (7.7%), while ‘Matilda’ (39.5%), ‘Elena’ (33.1%), and ‘Jubileu 50’ (31.9%) expressed symptoms and a higher percentage of infected fruits. All the data obtained are statistically supported. The results are encouraging, allowing a selection of resistant or tolerant cultivars to brown rot, considering the increasing impact of climate change. Furthermore, the global trend toward organic farming requires the use of resistant cultivars to problematic pathogens for successful farming

Preliminary evaluation of the competitiveness of PPV-Rec and PPV-D under field conditions

International audiencePPV-D, PPV-M and PPV-Rec are the three main strains of Plum pox virus (PPV), the most detrimental viral pathogen of stone fruits (Prunus sp.). While different experimental results reported that PPV-M is more aggressive than PPV-D, limited information are available about the competitiveness of PPV-Rec relatively to PPV-D or PPV-M. To provide this information, we monitored the PPV-Rec and PPV-D spreading in an experimental plum orchard (577 trees) located in Bistrita, Romania. The dynamic of spread of the two strains was monitored during four vegetative periods (2008-2011). The sanitary status of the trees was assessed visually and by ELISA testing each year. In 2008, the strain status of each PPV isolate was determined by IC- RT-PCR using strain specific primers located in the (Cter) CP, (Cter) NIb – (Nter) CP and the 6K1-CIP coding regions. From 2009 to 2011, strain typing was performed for every new disease case and for all single strain infections detected in the previous years, in order to check for possible over infection with the other strain. Disease incidence increased from 57 % (328/577) in 2008 to 72 % (414/577) in 2011. From a total of 328 infected trees in 2008, 58% of the trees were infected by PPV-Rec, 13 % by PPV-D and 29% were co-infected by PPV-D and PPV-Rec. The results on the rate of progression of PPV-D and PPV-Rec as well as the frequency of co-infections will be presented and a preliminary conclusion upon the competitiveness of PPV-Rec and PPV-D in our conditions will be discussed

Typing and distribution of Plum pox virus isolates in Romania. Julius-Kuhn-Archiv

Abstract Plum pox or Sharka, caused by Plum pox virus (PPV) is considered the most destructive disease of plum. Although PPV is widespread in all plum growing areas of Romania and causes serious yield losses, little is known about the variability of its isolates at a country level. For this reason, a large-scale study was performed with the aim of obtaining a picture of the prevalence and distribution of PPV strains in plum. During a three year survey, 200 PPV isolates collected from 23 different plum orchards from Transylvania, Moldavia and Muntenia areas were investigated. DAS-ELISA and IC-RT-PCR were used for PPV detection. PPV strains were serologically determined by TAS-ELISA using PPV-D and PPV-M specific monoclonal antibodies. Molecular strain typing was done by IC/RT-PCR targeting three genomic regions corresponding to (Cter)CP, (Cter)NIb/(Nter)CP and CI. RFLP analysis was used to distinguish D and M strains, based on the RsaI polymorphism located in (Cter)CP. To confirm the presence of PPV-Rec strain, 13 PCR products spanning the (Cter)NIb/(Nter)CP were sequenced. Overall results showed that in Romania the predominant strain is PPV-D (73%), followed, with a much lower frequency, by PPV-Rec (14%). Mixed infections (PPV-D+PPV-Rec), which might generate additional variation by recombination, are also frequent (13%)