Effective Biological Control of Carnation Fusarium Wilt Using a New Combination of Trichoderma Mutant Isolates

Fusarium infection in carnation is the most important limiting factor for carnation production. We isolated ۳۸ fungal isolates from infected carnation plants collected from Mahallat, Iran, and ۱۵ Fusarium species were identified morphologically. Isolates of J۱۴, k۵, and k۷۲ were the most pathogenic isolates in pathogenicity test on White Liberty cultivar. Molecular identification of J۱۴, k۵, and k۷۲ isolates was done based on Elongation Factor ۱-alpha (EF۱-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 ۲۵۰ Gy. The number of ۲۷۰ mutants were screened morphologically and ۶۰ mutants were screened using dual culture against J۱۴, k۵, and k۷۲. Morphological and molecular identification of J۱۴, k۵, and k۷۲ isolates recognized them as F. oxysporum. Three mutants, i.e. ThM۷(۶۷.۱۷%), TgM۱ (۵۹.۴۵%), and TvM۱۷(۵۷.۵۵%) 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 ThM۷, TgM۱, and TvM۱۷ (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.

Keywords:

Dianthus caryophyllus , Fusarium oxysporum , Gamma radiation , Induced mutation.