Production and characterization of a monoclonal antibody specific to the M serotype of plum pox potyvirus

A monoclonal antibody to an Albanian isolate of plum pox potyvirus (PPV) was obtained (MAbAL), that specifically recognized strain M of this virus. The specificity of MAbAL, assessed by comparative ELISA on 130 PPV isolates of different geographical origin, 22 of which were also tested by comparative IC-PCR, gave consistent and highly reproducible results. MAbAL seems to be elicited by a stable surface determinant that makes it particularly suitable for successful use under a wide range of conditions. MAbAL is an useful addition to the panel of PPV-specific MAbs available to date.     

Viruses of vegetable crops in Albania

Field surveys were carried out in the main vegetable-growing areas of Western and Central Albania to evaluate the sanitary status of open-field and protected cultivations of capsicum, tomato, potato, watermelon, cucumber, courgette, aubergine, lettuce, cabbage, chicory, leek and celery. The following viruses were detected: Alfalfa mosaic alfamovirus (AMV), Cucumber mosaic cucumovirus (CMV), Potato Y potyvirus (PVY), Tomato spotted wilt tospovirus (TSWV) and Watermelon mosaic potyvirus 2 (WMV-2). The virus found most frequently was CMV and all the isolates identified were of subgroup IA. AMV was also detected in several areas and all isolates were of subgroup II, suggesting a French origin. Finally, at the time of this survey, TSWV infections appeared to be moderately relevant and absent in protected crops. This is the first documented record of AMV, CMV, PVY, TSWV and WMV-2 in Albania. No infection by Tomato yellow leaf curl begomovirus (TYLCV) or Zucchini yellow mosaic potyvirus (ZYMV) was detected during this survey.     

Viruses of pome fruit trees in Syria

A survey was conducted to evaluate the sanitary status of pome fruit trees in Syria during spring 2003 and 2004 in 6 governorates: Damascus, Al-Qunaitara and Al-Sweida (Southern region), Homs and Hama (Central region) and Latakia (Costal Western region), as the main production areas of pome fruits. Leaf samples from 1077 apples, 54 pears and 14 quince were collected and tested for the presence of Apple chlorotic leaf spot virus (ACLSV), Apple stem grooving virus (ASGV) and Apple mosaic virus (ApMV) in 70 commercial orchards and 3 varietal collections by ELISA. Results showed that the virus infection rates were 34 and 2% in apple and pear, respectively. Quince trees were found to be virus tested free. ACLSV was prevailing on apple with 34%, whereas ASGV and ApMV were found in 2 and 0.2% of tested trees, respectively. Pear trees were infected only with ACLSV (2%). 21 apples and 15 pears representative budwood samples were indexed by grafting on the following indicators: (i) Malus pumila cvs. Virginia Crab and Radiant for apple and (ii) M. pumila cv. V. Crab and Pyrus communis cv. Nouveau Poiteau for pear. The virus infection rates by woody indexing were much higher than ELISA, Apple stem pitting virus (ASPV) and ASGV were found in 86 and 82% of apple tested samples, whereas they were 80 and 60% of pear tested samples, respectively. Additional RT-PCR testing carried out for a limited number of samples confirmed the high incidence of ACLSV ASPV, ASGV and the presence of ApMV. This is the first report on pome fruit viruses in Syria, indicating an unsatisfactory sanitary status of the industry. As a consequence, a certification program is recommended for producing locally healthy propagating material.     

Control and monitoring: monitoring and eradication of sharka in south-east Italy over 15 years

When the first foci of sharka were discovered in Puglia region (south-east Italy) in the late 1980s, the regional agricultural authorities launched a programme for Plum pox virus (PPV) monitoring and disease eradication. The infecting virus strain was identified as PPV-D. From 1989 to 1993, a strong eradication campaign was successfully carried out involving 13 plum and 2 apricot orchards with different levels of infection. During 1994–2000, besides plum, apricot and peach, monitoring was extended to sweet cherry. At that time, surveys and testing did not reveal any new PPV focus, but the eradication of infected trees continued in a couple of orchards. In 2001–05, particular attention was paid to peach, as devastating PPV-M outbreaks had developed in other areas of the country. A new PPV focus was found in apricot, caused by PPV-Rec, which was promptly eradicated. In the following two years, surveys in the once infected orchard and surrounding peach plantings did not detect any virus spread. The endeavour has taken 15 years making this PPV monitoring and eradication programme the longest in Italy. Its overall results indicate that the fruit tree industry in Puglia region can now be regarded as essentially PPV-free.     

Variant allometric scaling relationships between bud size and secondary shoot growth in <Emphasis Type="Italic">Quercus faginea</Emphasis>: implications for the climatic modulation of canopy growth

• Introduction and statement of the research questions  

The relationships between primary and secondary growth in tree populations of contrasting climates are poorly understood. We tested the hypotheses that bud size and stem cross-sectional area are related through allometric relationship in shoots and that their scaling slopes change in response to climatic stress.     

Simultaneous detection and genetic variability of stone fruit viroids in the Czech Republic

In this paper, we report a large-scale survey for the incidence of Peach latent mosaic viroid (PLMVd) and Hop stunt viroid (HSVd) in stone fruit collections and commercial orchards in the Czech Republic. From the 645 samples analysed, PLMVd was detected in 80 (26.6%) of peaches and the HSVd in 3 (1.3%) of apricot and 1 (0.33%) of peach trees. Sixty-seven accession of peach (44.6%) from the Czech Clonal GeneBank were infected by PLMVd. In addition, we used naturally infected trees to standardise the simultaneous detection of PLMVd and HSVd plus host mRNA as the control by means of one-step multiplex RTC-PCR. Eleven PLMVd and two HSVd isolates were sequenced and analysed. All the PLMVd variants were highly homologous (97–100%) to previously reported PLMVd variants from Tunisian peach and almond trees, and clustered together in the previously reported phylogenetic group III. The HSVd variants obtained from apricot and peach trees were included in the previously proposed recombinant group PH/cit3.     

Detection of Apricot latent virus and Plum bark necrosis stem pitting-associated virus by RT-PCR in Eastern Anatolia (Turkey)

Field surveys were carried out to determine presence and incidence of Apricot latent virus (ApLV) and Plum bark necrosis stem pitting-associated virus (PBNSPaV) in the main stone fruit growing areas of Eastern Anatolia. RT-PCR and nested-RT-PCR techniques were used to detect ApLV and PBNSPaV, respectively. Three apricot samples out of 224 tested positive for ApLV, although infected trees showed no apparent disease symptoms. Of 45 sweet cherry and plum trees tested for PBNSPaV, 35 tested positive. Stem pitting symptoms were observed on the trunks of PBNSPaV-infected sweet cherries. Trunk bark was spongy and thick; pits and grooves were observed on the woody cylinder. The overall incidence of ApLV was 1.3% and of PBNSPaV was 77%. This is the first report of ApLV and PBNSPaV in Eastern Anatolia, Turkey.     

Incidence and genetic diversity of Peach latent mosaic viroid and Hop stunt viroid in stone fruits in Serbia

Tissue-imprint hybridization (TIH) assay was validated for large-scale detection of Peach latent mosaic viroid (PLMVd) and Hop stunt viroid (HSVd). All 72 collected leaves (100%) from 2 PLMVd- and 2 HSVd-infected trees were positive in TIH, regardless of the geographic orientation of the scaffold, level of the canopy and position of the leaf in the shoot. In a large-scale survey in Serbia, we tested by TIH 871 trees of stone fruits, representing 602 cultivars from fruit collections in Belgrade, Čačak and Novi Sad. PLMVd was detected in 185 (50%) peach trees or 95 (54%) cultivars and HSVd in 2 apricot trees and cultivars (2%). The occurrence of HSVd is a new report for Serbia. No viroid infection was found in European plums, sweet cherries, sour cherries and wild Prunus spp. PLMVd-infected peach cultivars originated from the world’s main breeding centres of this crop. Western European and Asian cultivars were the most infected (58%) followed by those originating from North America (50%). Nine PLMVd and two HSVd isolates were sequenced and analyzed. All showed PMLVd sequences clustered together in the previously reported phylogenetic group III. Both HSVd isolates were found to be derived from recombinant events, but that of the cv. Saturn represented a putative new phylogenetic group of HSVd.