Harun Bayraktar

FIRST REPORT OF VERTICILLIUM DAHLIAE CAUSING VERTICILLIUM WILT ON GOJI BERRY IN TURKEY

Wilt symptoms of Goji berry plant (Lycium barbarum) were observed in nurseries in Bolu (Turkey) during a sanitary survey conducted in May 2015. One-year-old plants showed symptoms of wilting, stunting, yellowing, defoliation and vascular discoloration in the roots and stems. Small pieces of brownish vascular tissues were placed onto potato dextrose agar (PDA) after surface-disinfecting with 1% sodium hypochlorite. After 10 days of incubation at 25±1°C and 12 h photoperiod, many colonies developed with hyaline hyphae and irregular shaped black microsclerotia. The identification of fungal isolates was performed on the basis of morphological features such as elliptical single-celled conidia, verticillate conidiophores and microsclerotia (Hawksworth and Talboys, 1970). To confirm identity of the causal fungus, Verticillium dahliae, the internal transcribed spacer (ITS) region of rDNA was amplified for representative isolate using the primers ITS1/ITS4 (White et al., 1990) and sequenced (GenBank accession No. KX017569). BLASTn analysis of the 542 bp amplicon revealed 100% sequence identity with the sequence of a V. dahliae strain (AF104926). To fulfil Kochs postulates, 8-month-old Goji berry plants were inoculated by roots immersion into a conidial suspension (107 conidia/ml) for 30 min. Control plants were submerged in sterile tap water. All plants were transplanted into pots containing 1 l autoclaved soil and kept in a glasshouse. After 60 days, infected plants showed typical Verticillium wilt symptoms in the roots and stems, from which V. dahliae was consistently reisolated. To our knowledge, this is the first report of Goji berry Verticillium wilt disease in Turkey.

FIRST REPORT OF POWDERY MILDEW, CAUSED BY ARTHROCLADIELLA MOUGEOTII, ON GOJI BERRY IN TURKEY

Lycium barbarum, known as Goji berry or wolfberry, is a Chinese medicine plant in the family Solanaceae, and has been recently cultivated in Bolu, Turkey. During autumn 2015, severe powdery mildew symptoms were observed on Goji berry plantation area. White to grayish white fungal mycelia were shown on leaves and stems. Also, brownish discolorations and defoliation were exhibited. Microscope examination showed that conidia were formed in chains, hyaline, short-cylindrical and their length and width ranged from 19 to 31 (mean=26.2) μm and from 10 to 14.5 (mean=13.2) μm, respectively. Apothecial structures were not observed. The fungus was identified as Arthrocladiella mougeotii on the basis of morphological characteristics and the host specialization (Braun, 1987). To verify the identification, DNA isolation was performed by using the conidia collected by scraping from surface of infected leaves. The rDNA internal transcribed spacer (ITS) region including 5.8S rDNA was amplified using primers ITS5 (White et al., 1990) and p3 (Kusaba and Tsuge, 1995) and sequenced. The amplified 640 bp product (GenBank accession No. KX017568) revealed 99% genetic similarity with the sequences of an A. mougeotii isolate previously reported (AB022380). Pathogenicity was performed by gently pressing diseased leaves onto young leaves of one-year-old healthy plants. Non-inoculated Goji berry plants were used as control. All plants were transferred to a greenhouse. A month later, the fungus having identical morphological features was observed only on infected plants. To the best of our knowledge, this is the first report of A. mougeotii on Goji berry in Turkey.

FIRST REPORT OF PURPLE SPOT DISEASE OF ASPARAGUS OFFICINALIS IN TURKEY

In the course of a survey to determine the fungal pathogens of asparagus in Balikesir province (north-western Turkey) brown sunken lesions with dark purple margins were observed on the spears. Pseudothecia and ascospores were looked for in overwin- tering plant debris. Diseased tissues were surface-sterilized in 1% sodium hypochlorite for 2 min and placed on potato dextrose agar medium. The isolated fungus was identified as Stemphylium vesicarium based on morphological traits (Ellis, 1971), i.e. brown, oblong to broadly ellipsoidal and verruculose conidia (20 to 45×15 to 22 μm), with cross and longitudinal septa; pale to light brown conidiophores with a dark smooth or minutely verrucu- lose band; bitunicate and clavate asci (190 to 150×25 to 33 μm); light brown and ellipsoidal ascospores (35 to 45×15 to 22 μm). The identification was confirmed comparing the sequence of a 544 bp product (accession No. JX397964) amplified from the ITS region of the fungus under study by PCR using the primers ITS1/4 (White et al., 1990) with that of a comparable region of S. vesicarium rDNA present in GenBank. Asparagus seedlings (45- day-old) were sprayed with a suspension of 5×104 conidia/ml, then covered with polyethylene bags for 48 h and kept for 21 days at 22±1°C and a 14 h photoperiod. Symptoms comparable to those seen in the field were obtained and the fungus was con- sistently re-isolated from the lesions. S. vesicarium (telemorph, Pleospora herbarum), is an asparagus pathogen first recorded in the USA (Lacy, 1982). To our knowledge, this is the first report of asparagus purple spot disease in Turkey.

FIRST REPORT OF CROWN ROT CAUSED BY RHIZOCTONIA SOLANI AG-4 HG-I ON ASPARAGUS OFFICINALIS IN TURKEY

In 2011, crown rot symptoms were observed on the base, root and spears of asparagus plants in Balikesir province (north-eastern Turkey). Surface-disinfected tissues were placed on potato dextrose agar medium and incubated at 22±1°C. Rhizoctonia cultures were obtained and identified based on vegetative hyphae, nuclear staining, and anastomosis typing with known tester isolates of Rhizoctonia solani (Sneh et al., 1991). Positive anastomosis was observed with tester strain of AG-4. To confirm identity of the causal fungus, the complete ITS rDNA of a representative fungal isolate was amplified using primers ITS1 and ITS4 (White et al., 1990), and sequenced. The resulting sequence (GenBank accession No. JX437939) was compared with other sequences from database showing 97% identity with ITS sequences of strain AG-4 HG-I. To meet Koch’s postulates, inoculum was prepared by growing the fungus on sterilized wheat kernels and its pathogenicity was tested on 45-day-old asparagus seedlings inoculated by placing two colonized wheat kernels in contact with the base of each plant. After six weeks, plants were removed and assessed for disease symptoms. The fungus caused damping off of seedlings, brown-red lesions on roots and spears, and was consistently re-isolated from infected tissues. This pathogen was reported previously on asparagus seedlings in Japan (Sakaguchi et al., 1990). To our knowledge, this is the first report of crown rot on asparagus caused by Rhizoctonia solani AG-4 HG-I in Turkey.