Background: Random induced mutation by gamma radiation is one of the genetic manipulation strategies to improve the antagonistic ability of biocontrol agents.Objectives: This study aimed to induce mutants with more sporulation, colonization rate leading to enhanced antagonistic ability (in vitro assay) comparing to wild type (WT) and the assessment of genetic differences (in situ evaluation) using molecular markers. The superior mutants could be appropriate biocontrol agents against soil borne fungal diseases.Materials and Methods: In this research sampling and isolation of Trichoderma isolates were performed from soils with low incidence of soil borne disease.T. harzianum 65 was selected and irradiation was conducted with gammacell at optimal dose 250 Gray/s. Mutants (115) were obtained from the WT. The antagonistic abilities of twenty-four mutants were evaluated using dual culture and culture filtrate tests.Results: The results of in vitro assays revealed that Th15, Th11 and Th1 mutants exhibited stronger growth inhibition (GI) and colonization rate onMacrophomina phaseolina and Rhizoctonia solani AG4 compared to the wild type. Th15 and Th11 mutants exhibited stronger GI and colonization rate onSclerotinia sclerotiorum in dual culture and culture filtrate tests and Th1and Th11 mutants exhibited stronger GI on Fusarium grminearum in culture filtrate test.The DNA fingerprinting was carried out using RAPD and rep-PCR markers. Two (Th9 and Th17) out of the 24 mutants categorized distantly from the rest based on different polymorphism obtained by molecular markers. However, Th9 was different in GI% fromTh17. RAPD analysis separated WT from mutants, Th9 from Th17 and also phenotypically superior mutants from other mutants. Meanwhile, rep-PCR analysis categorized WT isolate and mutants according to their antagonistic properties.Conclusions: The latter marker (rep-PCR) appeared to be reproducible and simple to distinguish mutants from a single isolate ofT. harzianum. Mutants (3 isolates) were phenotypically and genotypically distinct from WT. These mutants demonstrated a pronounced biocontrol activities against SOILBORNE fungal phytoPATHOGENS.

Combining effects of soil solarization and grafting on SOILBORNE PATHOGENS, plant height and yield in cucumber were compared in a greenhouse of Bati Akdeniz Agricultural Research Institute located in Antalya in 2008 fall season. The experiment was set in split plot design containing; 1, 2, 4 and 5 months soil solarization (MSS), and non-solarized control plots (NSC) on which grafted Maximus F1+ Bergama F1 and non-grafted Bergama F1 were grown. Almost all of plants grown in nonsolarized plots were infected with root-knot nematodes with severe root damages; however, only a few plants were affected by this nematode in 4 and 5 months solarized plots with very slight root galls. No resistance to root-knot nematodes was observed in both grafted and non-grafted plants. Almost half of the plants grown on non-solarized control plots were infected with Fusarium oxysporum f. sp. cucumerinum with relatively slight disease symptoms. In conclusion, combining solarization with grafting significantly promoted early flowering time, plant vigor, early and total yields and reduced nematode and fusarium wilt damages in this study.

Beet SOILBORNE virus (BSBV) is a member species of the genus Pomovirus with rigid rod particles and 3 positive single stranded RNAs. The virus is transmitted by Polymyxa betae and restricted to Chenopodiaceae. A survey was conducted in 2005 for identification of BSBV in Northern Khorasan province. Samples showing yellowing, elongated and upright petioles with narrow leaf lamina and hairy roots were collected from fields of Shirvan, Bojnord and Esfarayen. Detection of BSBV was based on TAS-ELISA test. Our survey showed that different fields in Shirvan and Bojnord were infected with BSBV. Also for detection of mixed infection with BNYVV, samples were tested by DAS-ELISA as well. Our investigation showed that some fields in Shirvan and Bojnord had mixed infection with both viruses. This is the first report of infection with BSBV in Shirvan and Bojnord located in Northern Khorasan province.

Iran is considered a region of the world with low forest cover. Compared to other temperate areas with better soil conditions, it is difficult to achieve afforestation on a large scale and as a consequence, most of the afforestation is conducted with non-native species. Conifer afforestation is one of the forest development top priorities of Iranian forestry department in aiming at optimal use of marginal lands with less fertile and rockier and arid soils. One of the most important impacting factors that hinder the establishment of conifer plantations after afforestation is their poor growth and establishment followed by gradual decline of trees in some regions. There are a number of investigations carried out on the causes of death of conifer seedlings in nurseries, however very little work has been done on identifying causal agents of decline of coniferous trees. The objective of this study was to investigate the etiology of conifer decline with emphasize on identifying the role of biotic (fungal PATHOGENS) or abiotic (edaphic) factors. The geographical area of this research was Fars province, Iran including seven selected sites across the province as follows: Fasa, Arsanjan, Cheshmeh Abolmahdi, Zarghan, Shiraz, and Enghelab National Park (control) with the main focus on Cheshmeh Abolmahdi plantation as the major research site. During many field visits of research sites, roots/crowns of suspected declining trees and their surrounding soil were sampled by digging out soil profiles and suspected tissues were cultured on general (PDA), semi-selective (acidified PDA), and selective (PARP-CMA) media with/without surface sterilization after they were thoroughly washed under running tap water. In preliminary soil analysis of research and control sites general soil characteristics (texture, pH, and salinity) were measured. Isolated fungi were purified by single spore and/or hyphal tip techniques and identified using authenticate taxonomic keys/monographs. Pathogenicity of isolated fungi was investigated by inoculating young seedlings under greenhouse conditions after providing them with condition conducive for infection. Isolated fungi were identified as per following: Fusarium solani (nine isolates), Fusarium sambucinum, Fusarium avenaceum, Fusarium graminearum, Fusarium subglutinans, Fusarium crookwellens, Rhizoctonia solani, Binucleate Rhizoctonia solani like fungus, and Pythium okanoganens (one isolate of each). Two isolates of F. solani, one isolate of each of F. sambucinum, R. solani and P. okanoganens were pathogen on pine and/or cypress seedlings. Among these isolates the latter was relatively highly aggressive on pine seedlings whereas the others were not as much so. The role of soil texture (including compaction and hard pan layer), pH and salinity as possible contributing factors in gradual decline of conifer trees in research sites is discussed.

Two organic amendments (OMW-M1 and OMW-M2), based on olive mill wastes (OMWs) subjected to advanced processes of aerobic static storage or composting, were tested for their suppressive activity against Verticillium dahliae, the causal agent of olive Verticillium wilt. OMW-M1 and OMW-M2 drastically inhibited the pathogen growth in vitro and then were further tested in suppressive pot experiments. The amendments, mixed at 15% (v/v) with a nursery standard plant-growth matrix, were tested alone or in combination with two biocontrol bacteria (Bacillus amyloliquefaciens and Burkholderia cepacia) selected from suppressive soils. All mixtures were artificially contaminated with V. dahliae microsclerotia (MS), the density of which was periodically monitored by either a semi-selective medium or a specific real-time Polymerase Chain Reaction technique. In plant-less pot assays conducted in a growth chamber, OMW-M1 was the most effective amendment, reducing V. dahliae MS density by 100% after 90 days with respect to the untreated control. In nursery experiments with pot-growing olive plants, OMW-M1, particularly when combined with the biocontrol bacteria, confirmed its strong suppressive activity reducing up to 100% the density of V. dahliae MS in the rhizosphere behaving even better than a commercial biofungicide (Trichoderma asperellum TV1) used as a control. The best combined treatment also reduced plant mortality and increased root and shoot extension. It is concluded that organic amendments from stabilized olive mill by-products showed positive agronomic and phytosanitary properties on pot-growing olive plants and, particularly when enriched with biocontrol agents, they are potentially suitable for use in sustainable agriculture.

Beet SOILBORNE virus (BSBV) is a member of the genus Pomovirus, with rod shaped particles and three plus single - stranded of RNA. BSBV is morphologically similar to Beet necrotic yellow vein virus (BNYVV) and both are transmitted by the SOILBORNE fungus, Polymyxa betae Keskin that survives in soil for many years. Host range of BSBV is limited to the family of Chenopodiaceae. In order to detect and determine distribution of BSBV in Razavi Khorasan Province, in fall and summer of 2005, samples with distinct symptoms of the infection were collected from different fields. Infection of samples with BSBV was confirmed by Triple antiboby sandwich (TAS) ELISA. Also RT-PCR test was performed and its results confirmed the results from the ELISA. Total RNA was extracted from roots of infected samples by PEG6000 precipitation method and cDNA was synthesized using random hexamer primers. PCR was performed with the virus specific primers. After electrophoresis on 1.5% agarose, a~400 (399) bp segment was amplified from the infected samples.

One of the new methods for plant diseases management is application of plant extracts.SOILBORNE PATHOGENS fungal are world wide distributed and important phytoPATHOGENS. They cause yield losses in tobacco growing countries. The purpose of this study is to evaluate the antifungal activity of plant extracts on SOILBORNE PATHOGENS fungal of tobacco (Rhizoctoniasolani and Phytophthora nicotianae) and determine the best concentration of extracts on antifungal activity. The experiment was done in a factorial design based on completely randomized with three factors and five replications under in vitro condition. The first factors, plant extract (nine plant species), the second factor, solvent (five solvent) and the third factor, concentration (three concentration) were considered. In our previous study, experiments were carried out in pot condition based on factorial design with eight eentreatments and three replications in Tirtash Reaserch and Education Center, in 2013. In this study, the first factor including three plant extracts (catmint, tobacco and thyme), these cond factor, three concentration (0.5, 1 and 2 in 1000), and the third factor, treatment application of method two (spray and drench) were considered. The results indicated that different concentration of crude extracts of catmint, tobacco, thyme, fennel, hyssop and badrashbi have remarkable antifungal activity on the fungi. Methanol is perfect solvent for extraction of antifungal compounds. The maximum inhibitory concentration of eachextracts was 2000 ppm. The results of analysis variance showed that the effect of plant extracts on control of SOILBORNE PATHOGENS fungal of tobacco was significant at 1% level. Inour study, the interactions of "plant extracts × concentration", "concentration × application method" and also, "plant extracts × concentration × application method" was significant at1% level. Comparison of treatments means showed that extracts of both plant (catmit andtobacco) at 0.2% concentration were the best treatments with 80% and 75% inhibition off ungi, respectively.

SOILBORNE fungal plant PATHOGENS which cause damping-off, root and crown rot and reduce the seed germination lead to crop loss. The biocontrol fungus Trichoderma species is known as the most important antagonists against SOILBORNE fungal diseases. In this study, to improve the efficiency of biological control of antagonists, mutation induction by gamma irradiation was conducted in Gamacell with optimized dose of 250 Gy per second (rate of 0.23 Gy), and 24 mutants of Trichoderma harzianum 65 (wild type) isolate were selected. The study of antagonistic properties against Macrophomina phaseolina, Rhizoctonia solani AG4, Sclerotinia sclerotiorum and Fusarium graminearum was done in dual culture, volatile metabolites and extracellular extracts tests in a completely randomized design with three replications., Th15, Th11, Th5, Th1, Th4 and Th 22 mutants showed the maximum growth inhibition and was inroduced as superior mutants. These mutants have capaibility of evaluation in greenhouse biocontrol tests.

Dear Editor, Bacteria are traditionally categorized into two broad categories of pathogenic and non-pathogenic. Many infectious diseases in humans and animals are caused by pathogenic bacteria, including respiratory, gastrointestinal, genitourinary, and central nervous system infections, as well as plant infections. Therefore, they are wellknown. However, only a minority of bacteria species are pathogenic. This category includes free-living, commensal, and probiotic bacteria, which are beneficial for the body. Hence, wenaturally tend to the latter and try to avoid the former. But does this categorization work properly always? In another word, are all PATHOGENS in the first category harmful? While those in the second category are completely safe? Furthermore, should PATHOGENS socially be pictured as absolute evils while non-PATHOGENS are addressed as pure angels? We discussed this issue shortly to clarify the actual missions of the bacteria in life...