Verticillium dahliae is an economically important pathogen causing vascular wilt on more than 160 plant species. Most strains have a wide host range. Forty-five wild isolates of V. dahlia recovered from different woody and herbaceous plants throughout Iran. Genetic diversity of the isolates was assessed through vegetative compatibility groups (VCGs) using nitrate non-utilizing (nit) mutants. Nit mutants were generated using water agar supplemented with 5-7% KClO3. Nit mutants from different isolates were used in all possible combinations. Three VC local groups were identified and designated as VCGA, VCGB and VCGC which correspond to VCG2B (88.8%) and VCG 2A (8.8%) and weakly to VCG2A (2.2%) Most of the isolates were assigned to VCG2B. The results indicated that genetic diversity of V. dahliae is very low and there were no relationship between VCGs and geographicalorig in of the isolates. Host specificity of V. dahliae using 18 isolates was determined on 11 different hosts plant species. Different plants reacted differently to the isolates and were divided into three groups: very sensitive (eggplant, pistachio, cotton and okra), semi-sensitive (sunflower, radish and rapeseed) and low sensitive (pepper, tomato, small radish and cabbage). Each plant species reacted differently to each isolate. Mint was less sensitive to the pathogen (5 isolates) than other plant species tested.

Verticillium wilt is one of the most important vascular diseases of olive. For this reason, investigating different aspects of this disease such as distribution, biology, pathogenicity, and disease management have always been considered significant. In an attempt to investigate host-pathogen interaction, the present experiment was carried out to study the histopathology of olive (cultivar Zard) inoculated by Verticillium dahliae. Root-dipping method for 30 minutes was used for the inoculation of the seedlings by spore suspension with concentration 109 spore/ml. Four to twelve weeks after inoculation, with the occurrence of wilt symptoms, transversal sections were prepared from various parts of the stem and root. Then, very thin transversal sections were prepared and after different stages of staining, microscopic slides were prepared. The results of the microscopic investigations indicated that the causal agent of Verticillium wilt has caused disorders in the physiology through spreading into vessels, obstruction of xylem vessels, and their destruction. The casual agent also resulted in disorder in the flowing of vascular sap and caused shoot wilt. The results indicated that the seedlings obstructed the vessels and prevented the spread of pathogen with producing tylose. The pathogenicity and defensive mechanisms associated with host-pathogen interaction and their roles in susceptibility rate of the olive to Verticillium wilt have been discussed in this research.

Verticillium wilt is one of the most important vascular diseases of olive. It has always being considered to survey its various aspects such as distribution, biology, pathogenicity and management. In order to investigate host-pathogen interaction, this research was carried out to study histopathology of olive (cultivar Zard) inoculated by Verticillium dahliae. Root-dipping method for 30 min was used for inoculation of the seedlings by spore suspension with concentration 109 spore/ml. 4-12 weeks after inoculation, with occurrence of wilt symptoms; transversal sections were prepared from various parts of the stem and root. Then, very thin transversal sections were prepared and after different stages of staining, microscopic slides were prepared. The results of microscopic investigations showed that the causal agent of Verticillium wilt has caused disorders in physiology and flowing of vascular sap through spreading into vessels, obstruction of xylem vessels and their destruction. The results also showed that seedlings with producing tylose caused obstruction of vessels and prevented spreading of pathogen. Pathogenicity and defensive mechanisms associated with host-pathogen interaction and their roles at susceptibility rate of olive to Verticillium wilt had been discussed in this research.

This study was conducted on the interaction between Verticillium dahliae, the causal agent of vascular wilt of pistachio trees, and Acremonium kiliense, an endophyte fungus with biological control effects. Nine-month-old seedlings of three pistachio cultivars including Sarakhs, Badami-Rize-Zarand and Ghazvini were used by root dip method in conidial suspension (106 ml-1) and transferred to pots containing autoclaved soil. After one month, the inoculated seedlings were transferred to soil containing 40 microsclerotia/g soil of V. dahliae. The trial was performed as a two-factor factorial experiment with 3 replications for each combination, the factors being cultivars and fungal treatments at 3 and 4 levels, respectively, in a completely randomized design. The results showed an increase in the dry weight of roots and shoots in trees inoculated with A. kiliense plus V. dahliae compared to trees inoculated only with V. dahliae. Interaction of A. kiliense and V. dahliae decreased the percentage of shoots and roots infection compare to treatments of V. dahliae alone. The percentage of V. dahliae isolation from different treatments showed that cultivars inoculated with A. kilienseplus V. dahliae had a lower colonization by V. dahliae than those inoculated only with V. dahliae. The results of statistical grouping revealed that shoot dry weight in all inoculated cultivars with A. kiliense, A. kilienseplus V. dahliae, and control belonged to one group, whereas cultivars inoculated only with V. dahliae constituted a separate group. The results of the Verticillium isolation from tissue showed that the isolation rate of V. dahliae in interaction between A. kiliense - V.dahliae, compared to V. dahliae alone, decreased more than 50 percent in all cultivars.

Vascular wilt fungus, Verticillium dahliae, and root knot nematode, Meloidogyne incognita, are the most common and destructive pathogen factors in cotton. In order to study interactions between these two factors, their interaction effect on 4 cotton cultivars (Sahel, N200, Mehr and Varamin) was done in a completely randomized block design in 4 iterctions and 6 treatments in a greenhouse. Treatments including, control, just fungus, just nematode with concentration of 2300, just nematode with concentration of 7000, both fungus and nematode with concentration of 2300 and both fungus and nematode with concentration of 7000.12´104 Microsclerote for each fungus treatment and 7000 and 2300 nematode eggs and second stage juvenile for the nematode treatments respectively (depending on the desired treatment) were inoculated to 60 days old cotton seedling.Meloidogyne incognita nematode was isolated from the host plant and then its species and race were determined and at last it was reproduced by inoculation to tomato transplants. After that theVerticillium dahliae fungus was isolated from infected cotton plants and after cultivation and identification steps, it was transfered to the Tajan wheat seed cultivar (three times been autoclaved) for reproducing.The results of this review after 2 months showed that the interactions betweenVerticillium dahliae fungus and Meloidogyne incognita nematode in cotton was resonator. As a combination of fungus and nematode simultaneously leads to a significant increase (P=%1) in the wiltdejection. With increment in nematode concentration, root rot, the number of nodes and egg mass increased and shoot and root length, fresh and dry weight decreased vice versa.

Reaction of almond seedlings to Verticillium dahliae to one-year-old plants of 24 genotypes of Prunus dulcis and two genotype of Amygdalus orientalis and Amygdalus scoparia from Chahar Mahal va Bakhtiari province were investigated under greenhouse conditions. Seventeen-month after inoculation plants were removed from the pots and certain characters such as plant height reduction, rate of plant mortality, disease severity index, plant weight reduction, browning index and stem colonization were recorded. The results indicated that on the basis of these characters genotypes of almond were divided in to three groups; tolerant, susceptible and very susceptible. Shahrood 13, Shahrood 12, Sangi Shorab, Sangi Overgan, Talkheh Emamea, Talkheh Joneghan, Sangi Gahroo and Talkheh Sadeghabad were tolerant genotypes. Genotypes of Mamaee Emamea, Azar, Talkheh Ardal, Talkheh Horeh, Sangi Emamea, Sefid, Rabi, Shahrood 15, Shahrood 17, Amygdalus orientalis and Amygdalus scoparia were very susceptible.Other genotypes such as Mamaee, Sangi Joneghan, Talkheh Gahroo, Sangi Ahmadabad, Non-pareil, Shahrood 21 and Sangi Karimabad were susceptible.

The objective of this study was to determine the effect of Verticillium dahliae Kleb. on cotton yield and fiber technological properties, relationships among to disease and seed cotton yield, fiber yield and fiber technological properties and also determine susceptible and tolerant cotton varieties. The study was conducted in the Southeastern Anatolia Agricultural Research Institute’s experimental area during 2004-2006. The experiment was arranged as a randomized split block design with four replications. Main plot consisted of infected and non-infected area, sub-plot consisted of varieties. In this study 10 different commercial cotton varieties were grown to test the verticillium wilt performance. The results indicated that there were significant differences among varieties for all of the investigated characteristics. Area differences were significant for all of the investigated traits except ginning percentage. The results of the non-infected area showed that there were decreasing with regard to foliar disease index (FDI), vascular disease index (VDI), vascular disease rate (VDR), first picking percentage, fiber fineness, micronaire and yellowness, while increasing with regard to seed cotton yield, fiber yield, fiber length, strength, elongation, uniformity, reflectance and spinning consistecy index.Only ginning percentage was unaffected from area differences. With planting cotton varieties in non-infected area there were 323.60 kg ha-1 increase for seed cotton yield and 114.50 kg ha-1 for lint yield. Disease led to a decrease (7.86%) in seed cotton yield and (6.73%) in fiber yield. The results of this study indicated that GW-Teks, GW-Golda and Carmen varieties were tolerant, while Maras 92, Sayar 314 and Stoneville 453 were sensitive in terms of FDI, VDI and VDR and tolerant varieties can be used as parents in Verticillium breeding programs.

Seventy wild-type isolates of Verticillium dahliae were recovered from pistachio trees with Verticillium wilt symptoms in Kerman province. Seeds of ten commercial Pistacia vera cultivars including Qazvini, Badami Zarand, Badami Ravar, Sarakhs, Akbari, Ohadi, Sabz Peste Noogh, Khanjary Damghan, Kaleh Ghoochi and Ahmad Aghaee were established in virgin soils under greenhouse conditions. Microsclerotia were obtained in liquid medium. Six month-old seedlings were transplanted in soils containing 50 microsclerotia /g dried soil. Verticillium wilt symptoms were observed in all pistachio seedlings 67 to 95 days after inoculation. To study the reaction of pistachio cultivars to V dahliae, three distinct groups were identified. Cultivars Ohadi, Badami Ravar, Badami Zarand and Qazvini had the lowest and Sabz Peste Noogh, Khanjary Damghan and Ahmad Aghaee the highest disease severity index (DSI), browning index (BI), plant height reduction, stem colonization (SC) and death, which were regarded as tolerant and very susceptible group respectively. Cultivars Sarakhs, Akbari and Kaleh Ghoochi were between and considered as susceptible. Interaction between isolates of V dahliae (with different pathotypes) and pistachio cultivars that inoculated with conidial suspension (107/ml) of each isolate showed that DSI and SC of defoliating isolates were higher than non-defoliating type indicating that the isolates had different degrees of pathogenicity on pistachio cultivars.