---

Trichoderma is very important as a bio control agent and probably a good alternative for chemical fungicides. Fusarium oxysporum is a plant pathogen that causes wilt in a wide range of plants. The use of gamma irradiation can be employed to increase Trichoderma efficiency against F. oxysporum. The induced mutation provides genetic changes in Trichoderma and in some of the mutated isolates the efficiency of bio control may be improved. In this study the efficiency of mutated T. harzianum CS5 against the F. oxysporum f.sp. radicis-cucumerinum was evaluated. Among 16 wild isolates of Trichoderma, CS5 isolate was chosen based on synchronous and nonsynchronous mutual cultivation with pathogen. The spore suspensions of T. harzianum CS5 were irradiated in a cobalt- 60 γ- irradiator at a dose rate of 0.23 Gy/Sec in Nuclear Agriculture Research School, (NSTRI, AEOI). Then antagonist screening of 76 mutants was investigated in the experiments of synchronous and nonsynchronous dual culture with pathogen. The results showed that only 17 mutants were able to control the pathogen better than wild type, and YFTM80 isolate had the most prevention. Using the ERIC-PCR marker, the distinction was investigated between the wild type and the 17 selected mutants. The results showed that the gamma ray is able to improve biocontrol efficiency of Trichoderma and the ERIC-PCR marker can differentiate among derived mutants, but it does not have the ability to distinguish mutants from wild type. In terms of antagonistic superiority, mutations might have occurred in antagonistic sites, which have led to improved antagonistic efficiency. Probably the ERIC-PCR marker has failed to replicate these areas.

---

Carnation is an ornamental plant of economic importance worldwide. Fusarium fungus is one of the critical infectious agents of Carnation in Mahallat city. Some species of Fusarium cause wilting and crown and root rot in carnation. In this study, 20 fungal isolates of Fusarium were isolated from diseased carnation plants and rhizosphere samples from Carnation greenhouses in Mahallat. The isolates were identified morphologically using Leslie and Summerell’s identification key. Amplification of the TEF-1α gene region was done using ef1 and ef2 primers. Amplified fragments were purified and sequenced, and the nucleotide sequences were introduced in the Fusarium ID database for molecular identification of isolates based on the TEF-1α gene. A phylogenetic tree was also drawn. The results showed that Fusarium isolates were categorized into five species: F14 was identified as Fusarium brachygibbosum morphologically and F. solani molecularly. F6 was morphologically and molecularly identified as F. solani, F10 identified as Fusarium culmorum. All crown and root isolates (F11, F12, F13, F15, F16, F17, F18, F9, and F20) were identified as F. oxysporum. The rhizosphere isolates of F1, F2, F3, F4, F5, F7, F8, and F9 were identified as Fusarium proliferatum. This study shows that the use of the TEF-1α gene for molecular identification of Fusarium isolates is a relatively accurate, fast, and straightforward method for detecting species and can be used in plant pathological studies. Identifying the pathogen is the first step to controlling the disease.

---

Fusarium infection in carnation is the most important limiting factor for carnation production. We isolated 38 fungal isolates from infected carnation plants collected from Mahallat, Iran, and 15 Fusarium species were identified morphologically. Isolates of J14, k5, and k72 were the most pathogenic isolates in pathogenicity test on White Liberty cultivar. Molecular identification of J14, k5, and k72 isolates was done based on Elongation Factor 1-alpha (EF1-α) gene. To investigate the effect of Trichoderma and some of its mutants on reducing the Fusarium infection, six wild type isolates were examined. The species of T. harzianum, T. virense, and T. ghanens showed more inhabitation potential and were chosen for induced mutation via gamma irradiation at 250 Gy. The number of 270 mutants were screened morphologically and 60 mutants were screened using dual culture against J14, k5, and k72. Morphological and molecular identification of J14, k5, and k72 isolates recognized them as F. oxysporum. Three mutants, i.e. ThM7(67.17%), TgM1 (59.45%), and TvM17(57.55%) showed the highest efficacy and were selected. Evaluation test of efficacy in greenhouse by mixture of T. harzianum, T. virense and T. ghanens (TW) and mixture of mutant isolates ThM7, TgM1, and TvM17 (TM) showed that biological method had higher ability to control Fusarium infection on carnation plants in greenhouse condition, and mutation had no adverse effects on plants. The results of this experiment proved that the use of mutation in the Trichoderma genome with the use of gamma radiation could be an effective way to achieve isolates with better performance in this bio-control agent.