We describe a novel putative mycovirus infecting the conifer root-rot fungus Heterobasidion annosum sensu lato. This virus, designated as Heterobasidion RNA virus 6 (HetRV6), is taxonomically distant from all previously known viruses of Heterobasidion species, but somewhat related to the Curvularia thermal tolerance virus and the Fusarium graminearum virus 4. Based on a population analysis including 35 virus strains from Heterobasidion abietinum, Heterobasidion parviporum, Heterobasidion annosum sensu stricto and Heterobasidion occidentale, HetRV6 showed a considerable degree of geographical and host-related differentiation. The North American and Eurasian virus populations were clearly separated. In Eurasia, we observed cases of discrepancy between virus and host taxonomy, suggesting interspecies virus transfer. HetRV6 was also successfully transmitted between the three European species H. abietinum, H. annosum and H. parviporum. Based on growth rate tests on agar plates and spruce stem pieces, HetRV6 seemed to be cryptic or slightly mutualistic to its host.
and Bt2a/Bt2b, respectively (2). The DNA sequences of fungal isolates from California showed 99 to 100% homology with the ex-type Diplodia seriata De Not. (1) CBS 112555 deposited in GenBank. DNA sequences from three California isolates were submitted to GenBank with accession numbers KC937062, KC937065, KF481957, KF481598, KF481959, and KF481960. Pathogenicity tests were performed in March 2011 on 3-yearold Bartlett pear trees planted at an experimental farm in Davis, CA. A single, circular, 2-cm pruning wound at the top of the trunk was inoculated on each of three single-tree replications using 2-cm mycelial plugs from 14-day-old colonies growing on PDA. After inoculation, mycelial plugs were covered and sealed with Parafilm and aluminum foil for the duration of the trial. Three control trees were inoculated using sterile PDA plugs. Twelve months after inoculation, UCD103 and UCD105 were consistently re-isolated from the margin between necrotic and healthy tissue using the same methods described for the original isolation, and UCD102 was reisolated in two out of three plants. The average lesion lengths of UCD102, UCD103, UCD105, and control plants were 12.5, 17.3, 23, and 1 mm, respectively. Control lesions were short and sterile, and .seemed to be a physiological reaction from the plant. A second pathogenicity test was completed in 5 months beginning in June 2012. UCDI05 was consistently re-isolated, and UCD102 and UCD103 were re-isolated in two out of three plants. The average lesion lengths for UCD102, UCD103, UCD105, and control plants were 2, 3, 5, and 1 mm, respectively. Compared to grapevine (Vitis vinifera), the pathogen grows more slowly in pear tissue under natural conditions. To our knowledge, this is the first report describing D. seriata as a causal agent of pear branch canker in California. Canker diseases can reduce the lifespan of perennial plants, ultimately leading to long term economic losses for growers (3).Since 2010, a new foliar and fruit disease was observed in pomegranate {Púnica granattim L.) orchards in Alicante Province (eastern Spain). Symptoms included black spots on leaves and fruits, as well as chlorosis and premature abscission of leaves. Fungal isolates were obtained by surface-disinfecting small fragments of symptomatic leaf and fruit tissues in 0.5% NaOCl, double-rinsing in sterile water, and plating them onto potato dextrose agar (PDA) amended with 0.5 g/liter of streptomycin sulfate. Gray-to-black colonies were obtained, which were identified as Alternaria sp. based on the dark, brown, obclavate to obpyriform catenulate conidia with longitudinal and transverse septa tapering to a prominent beak attached in chains on a simple and short conidiophore (4). Conidia {n = 100) measured (12.2-) 20.2 (-27.6) x (5.7-) 9.2 (-12.0) um, and had 3 to 6 transverse and 0 to 5 longitudinal septa. Single spore cultures were obtained and their genomic DNA was extracted. The internal transcribed spacer (ITS) region of rDNA and partial sequences of the beta tubulin gene were amplified and seque...
Doğmuş-Lehtijärvi H.T., Kaya A.G.A., Lehtijärvi A., Oskay F., Kaya Ö.D. (2014): Occurrence and genetic similarity of Diplodia pinea on shoots and cones in seed orchards of Pinus spp. in north-western Turkey. Plant Protec Sci., 50: 217-220.Diplodia shoot blight disease can cause significant damage on coniferous trees and be particularly injurious to cones, which reduces the amount of seed production and germination. We investigated the disease severity and genetic variation of Diplodia pinea in one Pinus nigra and two P. sylvestris seed orchards. Disease surveys were carried out in İzmit (Marmara region, Turkey) in May 2012. Symptomatic shoots and cones were examined for the presence of pycnidia. Cultural and morphological characteristics of the isolates were studied using cultures grown on potato dextrose agar (PDA). Based on morphological characteristics and results using species specific primers, the pycnidia on shoots and cones were identified as D. pinea. In addition, Random Amplified Microsatellite Sequence (RAMS) analyses indicated that there was a single genet of D. pinea which caused the disease in the seed orchards. All of the 60 sampled trees were found to be infected by the fungus. There were differences in disease severity among the stands.Keywords: diplodia shoot blight; pine; RAMS; disease severity Diplodia pinea (Desm.) Kickx is a latent, opportunistic conifer pathogen which causes the disease commonly known as Diplodia shoot blight (Eldridge 1961;Swart & Wingfield 1991;Stanosz et al. 1997). The fungus affects both young and old trees causing shoot blight, dead top, sap stain, root disease, and cankers on stems and branches (Brookhouser & Peterson 1971;Peterson 1977).It mostly attacks Pinus species but also Abies Mill., Chamaecyparis Spach., Cupressus L., Larix Mill., Picea A. Dietr., Pseudotsuga Carriere and Thuja L. (Sinclair & Lyon 1987;Swart et al. 1987;Chou & MacKenzie 1988;Nicholls & Ostry 1990;Stanosz et al. 2001; Wingfield & Knox-Davies 1980;Palmer & Nicholls 1985;Rees & Webber 1988;Stanosz & Cummings-Carlson 1996). Although D. pinea has been already reported in Turkey (Günay 2001), little is known about the development of the disease in Turkish forests. Some of the most severe damages have occurred in southern Turkey. The pathogen was noted on dead twigs and canker samples of P. elderica and P. brutia in Kahramanmaraş in 2005. Several years later it was found on Pseudotsuga menziesii in İzmit province (Kaya et al. 2014). Studies carried out in the western part of the Taurus Mts. in Isparta province, located in the Mediterranean part of Turkey, showed that D. pinea was the most common cause of the shoot blight of P. brutia Ten. (Doğmuş-Lehtijärvi et al. 2007).In 2013, we investigated one P. nigra and two P. sylvestris seed orchards infested by D. pinea in Presented at the IUFRO Meeting "Biosecurity in Naturals Forests, Stands and Plantations, Genomics and Biotechnology for Biosecurity in Forestry", Brno and Cerna Hora, Czech Republic, May 20-25, 2013. 218 Vol. 50, 2014, No. 4: ...
Cedrus libani, commonly known as Lebanon cedar, is one of the most important coniferous tree species in Turkey. Its main distribution is in the Taurus Mountains in the Mediterranean Region. The total area of pure Taurus cedar forest covers 109,440 ha in Turkey, all located in the southwestern regions of the country. Due to its drought resistance, Taurus cedar has been commonly used for afforestations in these semi-arid areas (1). In September 2011, during surveys for Phytophthora spp. in forest nurseries in Adapazari and İzmir in eastern Turkey, initial symptoms such as death of fine roots, yellowing, and wilting of Taurus cedar seedlings were observed. Soil samples were collected from 10 symptomatic C. libani seedlings and isolation tests for Phytophthora species were carried out using leaflets from young Quercus suber, Azalea sp., and Rhodendron sp. saplings as baits floated over flooded soil. Necrotic baits were blotted dry, cut into small pieces, and placed on selective PARPNH carrot agar. Out growing colonies were subcultured on carrot agar and kept at 12°C for morphological and molecular identifications (2). In total, six Pythiaceous isolates were obtained from the C. libani soil samples. The isolates were investigated using a light microscope and grouped according to their morphological characteristics (3). DNA was extracted from two representative isolates using Qiagen DNeasy Plant Mini Kit following the manufacturer's instructions. PCR amplifications and sequencing of the internal transcribed spacer (ITS) region of rDNA and the β-tubulin gene were performed using ITS1 and ITS4 and Tub1 and Tub2 primer sets (4). Sequencing of the PCR products in both directions was conducted by IonTek Inc. (Istanbul, Turkey) in an ABI PRISM automated sequencer. The obtained sequences were compared with those in the GenBank and Phytophthora database using BLAST search. On the basis of morphological features and molecular analyses, the two isolates were identified as Phytophthora syringae. Morphological characteristics on carrot agar were identical with the description of P. syringae (2). At 20°C, colonies reached 7 cm in diameter after 1 week. Sporangia were semipapillate to non-papillate, ovoid, with average length of 59 μm (SD ± 2.8) (range 58 to 70 μm). Oogonia were 38 μm (SD ± 5.4) in diameter (range 30 to 47 μm) with paragynous antheridia. The morphological identification was confirmed by sequence comparison at GenBank with 99% homology for both ITS and β-tubulin. The ITS sequences of the two isolates were deposited in GenBank with the accession nos. KF430614 and KF944377. Under-bark inoculation tests with mycelia plugs were conducted with both isolates of P. syringae at 18°C in a growth chamber on a total of six 1-year-old shoots cut from two C. libani trees. Lesions with an average length of 19 mm (SD ± 6) developed after 10 days. P. syringae was consistently re-isolated from the margins of necrotic tissues. Control shoots remained symptomless. To our knowledge, this is the first report of damage caused by P. syringae on C. libani seedlings in forest nursery in Turkey. References: (1) T. Çalışkan. Pages 109-130 in: Proceedings of Workshop “Hızlı gelişen türlerle ilgili rapor,” Ankara, Turkey, 1998. (2) T. Jung et al. Eur. J. For. Pathol. 26:253, 1996. (3) T. Jung et al. Mycol. Res. 107:772, 2003. (4) L. P. N. M. Kroon et al. Fung. Genet. Biol. 41:766, 2004.
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