Mehmet Erhan Göre

Vegetative compatibility and pathogenicity of Verticillium dahliae isolates from chrysanthemum in Turkey

A collection of 30 strains of Verticillium dahliae, recovered during 2004–2006 from 12 cultivars of chrysanthemum (Chrysanthemum morifolium) in five districts of İzmir province in Turkey, was assigned to vegetative compatibility groups (VCGs) based on pairings of complementary nitrate-nonutilizing (nit) mutants induced on a chlorate-containing medium. Of these strains, nine were assigned to VCG1, seven to VCG2A, 11 toVCG2B and one to VCG4B. The remaining two strains could not be tested for vegetative compatibility because of their inability to yield nit mutants. Pathogenicity tests conducted by the root-dip method, demonstrated that wilt of chrysanthemum in Turkey is caused by V. dahliae, and most strains in VCG1 were significantly more aggressive to chrysanthemum than those in VCGs 2 and 4B. This is the first known study in the world of the VCGs of V. dahliae isolates from chrysanthemum.

Recovery of Verticillium dahliae from commercially available potato seed lots planted in Turkey and characterization of isolates by vegetative compatibility and aggressiveness

A total of 105 seed samples collected from commercially available potato seed lots in Turkey were assayed for Verticillium dahliae. V. dahliae was successfully isolated from 29 of the 105 seed lots tested. The frequency of infected lots was nearly 28%. Vegetative compatibility of the isolates was assessed through complementation tests using nitrate non-utilizing mutants. Of the 110 isolates obtained, 63 were assigned to VCG4A, 24 to VCG4B, 19 to VCG2A and one to VCG2B, while the three remaining isolates could not be assigned to any of the identified VCGs. All 36 of the isolates tested in the greenhouse on potato cv. ‘Russet Burbank’ were pathogenic to potato. As a group, AUDPC values were significantly higher (P <0.05) for VCG4A than for VCG4B and VCG2 isolates. These data suggest that (i) commercial potato seed lots are commonly infected with V. dahliae, and that this is a primary method by which the pathogen can be introduced into production fields; (ii) potato isolates of V. dahliae belong to VCG4A, 4B and 2A and these isolates are widely distributed via seed lots; and (iii) VCG4A and VCG4B are distinct pathotypes of V. dahliae that vary in their aggressiveness to potato. The present study is the first report of natural infections of potato by VCG4A and VCG2A in Turkey.

Searching for resistance sources to Verticillium wilt of cotton in seedlings from Gossypium spp.

Verticillium dahliae is a major wilt pathogen impacting cotton production in Turkey. Isolates of V. dahliae can be characterized as defoliating (D) or nondefoliating (ND) pathotypes based on symptom expression in cotton. Currently there are no fungicides identified that can manage this pathogen. Host resistance is the most economical and environmentally friendly means to manage this disease. Cotton genotypes, comprising the main cultivars and some breeding lines available in Turkey, were evaluated under controlled conditions for resistance to verticillium wilt. To establish adequate conditions for resistance expression, experiments examining isolate pathogenicity and the most appropriate inoculum concentration were carried out first. Based on the obtained data, 10 cultivars were then inoculated with D and ND pathotypes by the “pot immersion” method at 106 conidia/mL inoculum concentration and the plants were evaluated considering both internal and external disease symptoms. Plants were scored on a 0 to 4 scale for above-ground symptoms (0 = healthy; 4 = dead plant) ca. two weeks after inoculation. Significant differences in resistance level were observed among the genotypes (p < 0.05). The cultivar Maydos Yerlisi had the lowest level of wilt, with a mean rating of 1.0. The cultivar Nazilli NDT-15 had the strongest wilt, with a mean rating of 3.3. These results suggest that ‘Maydos Yerlisi’ can be used in cotton breeding programs to develop resistant varieties to V. dahliae.

Germination Stage Water Scarcity in Bread and Einkorn Wheat

Germination (GR, %) and power (GP, %) rates, coleoptile (CL, cm), shoot lenght (SL, cm), and root (RL, cm) length, shoot/root length ratio (SRLR), root fresh weight (RFW, mg) and dry (RDW, mg) weight, and root fresh/dry root ratio (RFDWR) of 12 bread and 10 einkorn wheat genotypes were investigated under 7 drought stress levels. SL and SRLR in the study were the most sensitive traits and followed by CL and RL. The mean performance of all traits was worsened starting at various stress levels. The highest percent reduction was in SL (100.00%), SRLR (100.00%), and RL (99.07%), and the lowest one was in GP (55.9%). The common applied drought tolerance indices grouped the entries as tolerant, moderate, and susceptible. Einkorn populations from higher rainfall Blacksea region responded worse under drought stress than bread wheat cultivars, which were improved for drier or relatively drier Central Anatolia, Sub-Marmara, and Thrace regions.