Çiğdem Ulubaş Serçe

Comparison by Sequence-Based and Electron Microscopic Analyses of Fig mosaic virus Isolates Obtained from Field and Experimentally Inoculated Fig Plants

Fig mosaic disease (FMD) and the fig mite, Aceria ficus, are widespread in different fig growing provinces of Turkey. Fig trees (Ficus carica) cv. Bursa siyahı (D1) and an unknown seedling (D2) that showed typical FMD symptoms and was heavily infested by fig mites were used as donor plants for attempted mite transmissions to healthy fig seedlings. Transmission electron microscopy observations of donor plant samples prior to the transmission tests were performed and showed the presence of double membrane bodies (DMBs) in the palisade mesophyll cells. Electron microscopy of all experimentally inoculated fig seedlings showed the same bodies. This result reinforced the suggestion that an agent that elicits the production of DMBs in infected cells is involved in the etiology of FMD. Double-stranded (ds)RNA analyses were also performed from experimentally inoculated plants, and dsRNAs with sizes approximately 1.30 and 1.96 kb were obtained. Reverse transcription-polymerase chain reaction (RT-PCR) products of 468 and 298 bp specific to Fig mosaic virus (FMV) were amplified from both donor and experimentally inoculated plants. BLAST analyses of nucleotide sequences of these fragments showed 90% identity with FMV for the donor plant and 94 to 96% for experimentally inoculated plants. According to these results, FMV is present in both donor and experimentally inoculated plants in Turkey, and this virus is transmissible by A. ficus from fig plant to fig plant.

Potential vectors of Plum pox virus in the Eastern Mediterranean Region of Turkey

Although Plum pox virus (PPV) was first detected in Turkey 44 years ago, the virus is present in a rather limited number of trees. Our recent studies on PPV incidence showed that PPV was introduced rapidly in PPV-free regions and that there are no data available about the role of aphid species and Prunus rootstocks on these new infections. In this study the epide- miological aspect of PPV was studied in Antakya-Hatay, located in the Eastern Mediterranean region of Turkey where PPV was first detected in 2011. The susceptibility of different Prunus rootstocks to PPV was evaluated in an established experimental plot next to a PPV-infected nectarine orchard. Aphid populations were monitored in 2011 and 2012 from the last week of April to the middle of June by the sticky-plant method in both the experimental plot (EP) and the surrounding infected nectarine orchard (SNO). Regularly collected plant samples and aphids were individually tested by DASI-ELISA and squash real-time RT-PCR, respectively. The highest aphid population densities were observed at the end of May in both years. The most abundant aphid species were Aphis gossypii and A. spiraecola both in EP and SNO in both years. The percentage of PPV-viruliferous Myzus persicae, A. fabae, A. gosypii, A. spiraecola, Hyalopterus pruni, Macrosiphon euphorbiae and A. craccivora as estimated by squash real- time RT-PCR were 39.47%, 25.00%, 24.56%, 22.60%, 22.22%, 20.00% and 8.00%, respec- tively. The percentages of viruliferous aphids collected from SNO were 12.5% in A. spiraecola, 12.42% in A. gossypii and 11.11% in H. pruni. At the end of 2012, three Myrobolan 29C and two Adesoto 101 rootstocks were found infected by PPV. Molecular characterization studies showed that PPV-M was the strain present in both the originally infected nectarine plot and the Myrobolan 29C rootstocks.

EVALUATION OF THE SUSCEPTIBILITY OF DIFFERENT PRUNUS ROOTSTOCKS TO NATURAL INFECTION OF PLUM POX VIRUS-T

SUMMARY Plum pox virus (PPV) has been observed in Turkey since 1968, but was not widespread except in apricot and plum trees in home gardens and ornamental parks in restricted areas. Susceptibility of six different Prunus rootstocks to strain PPV-T was assessed under natural inoculum pressure in the Izmir-Aegean region during 2010-2011. Aphid populations were monitored from the first week of April to the middle of June by the stickyplant method one year after the rootstock plantation was established. Aphids collected from different rootstocks were tested individually by squash real-time RT-PCR and all rootstocks were regularly tested by DASI-ELISA. The largest aphid populations were observed at the end of May and the most abundant aphid species as averages over the two years were Myzus persicae (20.15%), Hyalopterus pruni (18.64%), Aphis craccivora (9.04%) and Aphis gossypii (8.36%). In 2011, the highest percentage of viruliferous aphids was found in M. persicae (34.78%), followed by H. pruni (32.50%), Macrosiphum euphorbiae (25.00%), A. gossypii (23.80%), A. spiraecola (12.50%) and A. craccivora (10.00%). Of the six Prunus rootstocks tested, only Nemaguard and Myrobalan 29C were infected by PPV-T, infection rate in 2010 being 6.0% (Nemaguard) and 4.0% (Myrobalan 29C). The infection rate increased to 16.0% for Nemaguard and 14.0% for Myrobalan 29C in 2011. However, the other rootstocks, Prunus marianna GF8.1, Docera6, GF677 and Garnem tested negative for PPV-T throughout 2011. PPV isolates obtained from naturally infected apricot trees (inoculum source) and from infected rootstocks in the experimental plot were characterized as PPV-T and had more than 99.5% nucleotide sequence identity.

First Report of a Root Rot Caused by Phytophthora palmivora on Lavandula angustifolia in Turkey

English Lavender (Lavandula angustifolia Mill.) has been considered an alternative crop to tobacco in Hatay Province of Turkey because of its great production potential. As a new, nonnative crop, diseases and pests of lavender are not well known in the region. In summer 2010, root rot symptoms were observed with an average incidence of 45% in a 2-year-old lavender nursery in Hatay. Initial symptoms of chlorosis and wilting were followed by progressive death of the plants starting at the shoot tips. An oomycetous species was isolated consistently from the stems and roots of diseased plants on potato dextrose agar (PDA) amended with several fungicides and antibiotics. The culture of the single-zoospore isolate produced arachnoid growth on PDA. Chlamydospores of the isolate were approximately 35.0 μm in diameter. The isolate produced papillate, caduceus, hyaline sporangia in different shapes ranging from spherical to ellipsoidal. Sporangia with short pedicels (5 μm) were 35.0 to 57.5 × 27.5 to 42.5 μm with a length/width ratio of 1.2 to 1.8. On the basis of symptoms and morphology of the organism, the pathogen was identified as Phytophthora palmivora (E.J. Butler) E.J. Butler (3). Identification of the isolate was also confirmed by comparison of the sequence of the nuclear ribosomal internal transcribed spacer (ITS) region with reference isolates. The ITS region of rDNA was amplified by PCR with primers ITS1/ITS4 and sequenced (GenBank Accession No. JF777117). BLAST analysis of the sequence obtained showed a 99 to 100% homology with P. palmivora. Pathogenicity tests were performed on 12 greenhouse-grown 2-year-old lavender plants in 2-liter pots containing a steamed sand/peat/soil mixture. After rooting, the plants were inoculated by placing mycelial plugs from a 1-week-old culture of the isolate into an incision made at the base of each plant. Control plants were treated with plugs of sterile PDA. Inoculated plants were kept at 27°C for 5 weeks. Similar symptoms developed on the inoculated plants within 4 weeks after inoculation. P. palmivora was consistently reisolated from symptomatic plants. No symptoms developed on control plants. P. palmivora attacks a wide range of crop species including lavenders (1,2,4). To our knowledge, this is the first report of a root rot caused by P. palmivora, a new pathogen of lavender in Turkey. References: (1) S. Davino et al. Plant Dis. 86:561, 2002. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St Paul, MN, 1996. (3) D. J. Stamps. C.M.I. Descr. Fungi Bact. 831:1, 1985. (4) G. A. Torres et al. Plant Dis. 94:1163, 2010.

Phylogenetic analysis of partial sequences from Fig mosaic virus isolates in Turkey

Fig mosaic virus (FMV), which was described recently, is the only characterized causal agent of fig mosaic disease (FMD). It has six RNA segments and belongs to the Bunyaviridae family. In order to determine the genetic diversity of Turkish FMV isolates, the most common fig cultivars showing FMD symptoms were collected from different fig-growing provinces of Turkey. Nucleoprotein (Np) and Glycoprotein (Gp) gene-specific primers of FMV were used for RT-PCR analysis. According to RT-PCR results, 71 of 90 samples from 20 different cultivars and unknown fig seedlings were found to be infected by FMV. Among them, 41 isolates were sequenced and subjected to phylogenetic analyses based on the partial Gp and Np sequences at the amino acid level by the neighbor-joining method. The isolates showed more than 80% identity with reference FMV isolates (Acc. nos. FM991954.1 and FM864225.2). Based on phylogenetic analysis, the sequences clustered into two main groups for Np and Gp regions. Significant relationships between FMV isolates based on geographic origin and cultivars were not observed.

First report of Grapevine Roditis leaf discoloration-associated virus infecting grapevine (Vitis vinifera L.) in Turkey

Grapevine (Vitis vinifera L.) is one of the major crops in Turkey; production exceeded 3.5 million tons in 2015. In a vineyard survey conducted during June 2016, main and lateral vein clearing and yellowing as well as leaf deformations were observed on grapevines in the Adana province of Turkey. Total RNA was extracted from 45 grapevine leaf samples collected from 15 vineyards with ZR RNA MiniPrep™ (Zymo Research, USA), and cDNAs were synthesized using EasyScript Plus™ cDNA Synthesis kit (Abm, Canada) to test the samples for several grapevine RNA or DNA viruses. Reverse transcription (RT)-PCR assays were also conducted with the primer pairs BadnUp-6262 5’- GAA AGA CGA ACC CTT CAT CAT GAA G -3’ and BadnDo-6757 5’- CCC CAT CGA CAG CTC ACA AG -3’ which amplify a 495 bp region of Grapevine Roditis leaf discoloration-associated virus (GRLDaV) (Maliogka et al., 2015). Four plant samples (isolates B34, B36, B42, B50) collected from three different vineyards were found positive for GRLDaV. The PCR products were d...

POTENTIAL PSYLLID VECTORS OF CANDIDATUS PHYTOPLASMA MALI AND CANDIDATUS PHYTOPLASMA PYRI IN TURKEY

Fruit tree diseases caused by phytoplasma have great economic effects on fruit production, especially in Europe. A major phytoplasma is ‘Candidatus Phytoplasma mali’, which causes apple proliferation (AP) disease mainly in cultured and wild forms of apple trees (Seemuller et al., 2011a); however, there has been a report of different hosts, including Prunus avium (L.) L., P. armeniaca L., and P.domestica L. (Mehle et al., 2007). ‘Ca. Phytoplasma pyri’ causes pear decline (PD) disease that is found mainly in cultured and wild forms of pear (Pyrus spp.) and quince (Cydonia oblonga Mill.) (Seemuller et al., 2011b). These phytoplasma are taxonomically classified into the 16SrX group (or AP-group) of phytoplasmas and constitute closely related subgroups (Seemuller and Schneider, 2004). Phytoplasmas are mainly spread by vegetative propagation or the grafting of infected plant material and phloem feeding insects, primarily leafhoppers, planthoppers and psyllids (Weintraub and Beanland, 2006). Only one genus of this last one, Cacopsylla spp., transmit AP-group phytoplasmas to pome and stone fruit trees. In apple orchards, ‘Ca. P. mali’ can be transmitted by two psyllid species. Cacopsylla (Thamnopsylla) picta (Foerster, 1848) (syn. C. costalis) has been reported main vector in Germany (Jarausch et al., 2003, 2011) and northern Italy (Frisinghelli et al., 2000; Carraro et al., 2008), while Cacopsylla (Thamnopsylla) melanoneura (Foerster, 1848) was identified as main vector in Aosta Valley (Tedeschi et al., 2002). C. picta is monophagous on Malus spp. and until now this species have been described only in Europe (Burckhardt, 1994; Ossiannilsson, 1992; Ouvrard, 2014) and Turkey (Klimaszewski and Lodos, 1977, 1979; Drohojowska and Burckhardt, 2014). C. melanoneura has a Palaearctic distribution and is oligophagous on Rosaceae, its principal host plant being a common shrub, hawthorn (Crataegus monogyna L.) (Ouvrard, 2014). In most of studied cases, both psyllid species are present in apple orchards (Jarausch et al., 2003; Delic et al., 2005; Carraro et al., 2008; Mattedi et al., 2008). Two others species living on hawthorn, Cacopsylla peregrina (Foerster, 1848) and Cacopsylla (Thamnopsylla) affinis (Low, 1880), were found able to harbor the phytoplasmas of the AP-group, in particular ‘Ca. P. mali’ (Tedeschi et al., 2009). Their transmission ability was not proven but this result highlights the potential role as vector of these psyllid species. In pear orchards, until recently, two psyllid species were known as vector of ‘Ca. P. pyri’. Cacopsylla (Hepatopsylla) pyricola (Foerster, 1848) has been reported for Great Britain (Davies et al., 1992) and North America (Jensen et al., 1964), while Cacopsylla (Hepatopsylla) pyri (Linne, 1758) was described as the vector in France (Lemoine 1984), Italy (Carraro et al., 1998a) and Spain (Garcia-Chapa et al., 2005). C. pyri is widespread in Europe, in the Caucasus, Georgia, the Middle Asia, including Turkey (Klimaszewski and Lodos, 1979; Burckhardt and Pak. J. Agri. Sci., Vol. 53(2), 383-392; 2016 ISSN (Print) 0552-9034, ISSN (Online) 2076-0906 DOI: 10.21162/PAKJAS/16.3804 http://www.pakjas.com.pk