Sibel Dervis

Vegetative compatibility groups in Verticillium dahliae isolates from olive in western Turkey

Verticillium wilt, caused by Verticillium dahliae, is the most serious disease in olive cultivation areas in western Turkey. Two hundred and eight isolates of V. dahliae from olive (Olea europea var. sativa) trees were taken for vegetative compatibility analysis using nitrate non-utilizing (nit) mutants. One isolate did not produce a nit mutant. Nit mutants of 207 isolates were tested against tester strains of internationally known vegetative compatibility groups (VCGs) 1A, 2A, 2B, 3, 4A and 4B, and also paired in many combinations among themselves. One hundred and eighty nine of the isolates (90.9%) were strongly compatible with T9, the tester strain of VCG1A, and thus were assigned to VCG1A. Eight isolates were assigned to VCG2A and four isolates to VCG4B. One isolate was heterokaryon self-incompatible (HSI) and five isolates could not be grouped to any of the VCGs tested. Pathogenicity assays were conducted on a susceptible olive cultivar (O. europea cv. Manzanilla) and a susceptible local cotton cultivar (Gossypium hirsutum cv. Çukurova 1518). Both cotton and olive inoculated with all VCG1A isolates showed defoliating symptoms in greenhouse tests. This is the first report on VCGs in V. dahliae from olive trees in Turkey which demonstrates that VCG1A of the cotton-defoliating type is the most commonly detected form from olive plants in the western part of Turkey.

Vegetative compatibility groups inVerticillium dahliae isolates from cotton in Turkey

Verticillium dahliae Kleb. with a complicated genetic diversity is a widely distributed major pathogen resulting in cotton wilt, which causes high economic losses in cotton lint production in the cotton belt of Turkey. A collection of 70 TurkishV. dahliae isolates (68 from wilted cotton plants in 28 districts and two from watermelon plants in two districts) were tested for vegetative compatibility by observing heterokaryon formation among complementary nitrate-nonutilizing (nit) mutants. The mutants were tested against international reference tester isolates and also were paired with one another. Thirty-nine isolates were assigned to vegetative compatibility group (VCG) 2B, 19 to VCG2A and three to VCG4B. One isolate was self-incompatible and eight others could not be assigned to any of the identified VCGs because theirnit mutants showed negative reactions with the tester isolates of four VCGs or theirnit mutants reverted back to the wild type. This is the first report of VCGs inV. dahliae from cotton in Turkey.

Genetic and pathogenic characterization of Verticillium dahliae isolates from eggplant in Turkey

During 2005 to 2007, eggplant fields in 19 provinces from three different regions (western, southern and southeastern Anatolia regions) of Turkey were surveyed for Verticillium wilt. Sixty-seven isolates of Verticillium dahliae from wilted eggplants were collected and used for vegetative compatibility analysis using nitrate non-utilizing mutants and reference tester strains of vegetative compatibility groups (VCGs) 1A, 2A, 2B, 3, 4A and 4B. Among all isolates, 33 (12 from western, 15 from southern and six from southeastern Anatolia) were assigned to VCG2B, 23 (four from western, eight from southern and 11 from southeastern Anatolia) to VCG2A, six (four from southern, one from western, and one from southeastern Anatolia) to VCG4B and five (one from western, one from southern and three from southeastern Anatolia) to VCG1A, whereas VCG3 and VCG4A were not defined among isolates. In order to test if there is a correlation between VCG and pathogenicity in V. dahliae, pathogenicity of 30 isolates, representing the four multimember VCGs, were tested on Solanum melongena cvs. ‘Kemer’ and ‘Aydın Siyahı’ in an unheated greenhouse. All isolates were found to be pathogenic on both cultivars and there was no difference in susceptibility between the two cultivars. VCG4B isolates collectively led to higher vascular discoloration index (VDI) on both cultivars and higher disease severity index (DSI) on ‘Kemer’ compared with other VCGs. Similarly, VCG1A caused lower VDI on both cultivars and lower DSI on ‘Kemer’. Isolates within each of VCGs 1A, 2A and 4B caused similar VDI on both cultivars. Isolates of VCG2B were found to vary in their VDI values on both cultivars. To the best of our knowledge, the present study is the first report of natural infections of eggplant by VCG1A.

Vegetative compatibility groups ofVerticillium dahliae from cotton in the southeastern anatolia region of Turkey

Eighty isolates ofVerticillium dahliae from the southeastern Anatolia region and 20 isolates from the east Mediterranean region from wilted cotton plants were used for vegetative compatibility analysis employing nitrate non-utilizing mutants and reference tester strains of vegetative compatibility groups (VCGs) 1A, 2A, 2B, 3, 4A and 4B. Of the 100V. dahliae isolates, 49 were assigned to VCG1A, 39 to VCG2B, nine to VCG2A and three to VCG4B. Pathogenicity assays were conducted on susceptible cotton cv. Çukurova 1518 in the greenhouse. All VCG1A isolates induced defoliation and all VCG2B isolates caused partial defoliation symptoms. Isolates of VCG2A and VCG4B caused typical symptoms of leaf chlorosis without defoliation. This is the first report on VCGs ofV. dahliae in the southeastern Anatolia region of Turkey, which demonstrates that VCG1A of the cotton-defoliating type and VCG2B of the partially defoliating type are prevalent in this region.

Gall production on hawthorns caused by Gymnosporangium spp. in Hatay province, Turkey

Three hawthorn and related rust diseases caused by Gymnosporangium confusum on Crataegus monogyna, Gymnosporangium clavariiforme on Crataegus orientalis and Gymnosporangium sabinae on Pyrus communis were detected in Hatay province, Turkey. G. confusum was also found causing telial galls on Juniperus communis. G. confusum and G. clavariiforme produced aecial horns on overwintered galls on hawthorn twigs from May to June. The production of galls caused by Gymnosporangium on the secondary host is unusual. Portions of the nuclear ITS and LSU rDNA were sequenced for all three species of Gymnosporangium for use as a species barcode; sequences were deposited in GenBank. Sequence data from G. clavariiforme and G. sabinae matched those in GenBank; however, this is the first study to deposit sequence data from G. confusum to GenBank. The life cycles of G. confusum and G. clavariiforme are discussed along with implications for disease control.

Pathogenic races and inoculum density ofFusarium oxysporum f.sp.niveum in commercial watermelon fields in southern Turkey

Systematic surveys forFusarium oxysporum f.sp.niveum (Fon) were conducted in a total of 141 fields in the watermelon-growing areas of the Mediterranean and southeastern Anatolia regions of Turkey in 2004 and 2005. The mean incidence and prevalence of the disease were higher in the southeastern Anatolia region than in the Mediterranean region. Maximum disease incidence during the 2-year survey was 46.3%. However, mean disease prevalence ranged from 27.3% to 63.6% in southern Turkey. Of the 33 isolates ofFon recovered, 19 were recovered from Adana, two from Mersin, one from Gaziantep, four from Sanlıurfa, five from Adıyaman, one from Batman, one from Diyarbakır. The physiological race of each isolate was determined by the disease reaction in five differential watermelon cultivars (Citrullus lanatus (Thunb.) Matsum. & Nakai). Of the isolates recovered from the Mediterranean region, 47.6% were identified as race 0, 38.1% as race 1, and 14.3% as race 2. Among the 12 isolates recovered from the southeastern Anatolia region, four isolates were identified as race 0, and eight isolates as race 1. Race 2 was not detected in this region. This is the first report ofFon races 0 and 1 in southeastern Anatolia. The population density ofFon in both the Mediterranean and southeastern Anatolia regions ranged from 116.1 to 4444.7 CFU g−1 of soil. The mean inoculum density was much higher in watermelon-growing areas in the southeastern Anatolia region in comparison with the Mediterranean region, with a mean inoculum density of 1547.2 CFU g−1. Race 0 and race 1 were the most prevalent races in the fields with the mean highest and lowest inoculum density, respectively.

Analysis of genetic diversity of Sclerotinia sclerotiorum from eggplant by mycelial compatibility, random amplification of polymorphic DNA (RAPD) and simple sequence repeat (SSR) analyses

ABSTRACT The genetic diversity and pathogenicity/virulence among 60 eggplant Sclerotinia sclerotiorum isolates collected from six different geographic regions of Turkey were analysed using mycelial compatibility groupings (MCGs), random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) polymorphism. By MCG tests, the isolates were classified into 22 groups. Out of 22 MCGs, 36% were represented each by a single isolate. The isolates showed great variability for virulence regardless of MCG and geographic origin. Based on the results of RAPD and SSR analyses, 60 S. sclerotiorum isolates representing 22 MCGs were grouped in 2 and 3 distinct clusters, respectively. Analyses using RAPD and SSR markers illustrated that cluster groupings or genetic distance of S. sclerotiorum populations from eggplant were not distinctly relative to the MCG, geographical origin and virulence diversity. The patterns obtained revealed a high heterogeneity of genetic composition and suggested the occurrence of clonal and sexual reproduction of S. sclerotiorum on eggplant in the areas surveyed.

First report of Phytophthora crown and root rot of cherry caused by Phytophthora palmivora in eastern Turkey

Abstract Crown and root rot or decline is an increasing problem on sweet cherry in Mardin, Malatya, Elazığ and Diyarbakır provinces in eastern Turkey. A survey was carried out during 2012–2014 in 120 commercial cherry orchards for disease symptoms, which included poor growth with sparse off-colour foliage, reddish-brown discolouration of the crown and roots, wilting and dieback of the canopy, and in many cases, tree death. Fifty-eight Phytophthora isolates obtained during the course of this 3-year survey were examined and identified as Phytophthora palmivora on the basis of morphological characteristics. BLAST analysis of ITS region sequences of rDNA of five isolates revealed 99–100% identity with reference isolates of P. palmivora from GenBank and Phytophthora database. Isolates of P. palmivora were pathogenic on 12-month-old potted ‘Mahaleb’ cherry (Prunus mahaleb L.) rootstock seedlings that were wound-inoculated on the roots and on the crown. Inoculated plants expressed similar symptoms to those observed in the field and almost all infected plants died within 3 months after transplanting. This study demonstrated that P. palmivora is the causal agent of cherry decline in eastern Turkey. To our knowledge, this is the first report of P. palmivora on this host plant.

Production of Antioxidant and Oxidant Metabolites in Tomato Plants Infected with Verticillium dahliae Under Saline Conditions

The objective of this research was to study the levels of antioxidant and oxidant metabolites such as total protein, total soluble sugars, proline, peroxidase, catalase, malondialdehyde, anthocyanin and phenol contents in tomato plants (Lycopersicon esculentum Mill. cv. Ailsa Craig) inoculated with Verticillium dahliae under various NaCl concentrations (50, 100, 200 and 250 mmol l−1). V. dahliae alone resulted in increases in oxidant (malondialdehyde and phenol) and antioxidant metabolites (proline, anthocyanin and sugar) as well as in antioxidant enzymes (catalase and peroxidase). However, the pathogenic effect of V. dahliae increased with the increase of NaCl stress and resulted in depletion of antioxidant metabolites and enzymes after 150 mmol l−1 NaCl level, while oxidant levels showed an increased trend. Results suggest that V. dahliae could be able to survive under high salt stress conditions and cause combined stress that affect the resistance of the resistant cultivars and reduce crop yield.