Resistance and activity of phytopathogenic and potential antagonistic soil filamentous fungi under the action of heavy metals
E. V. Fedoseeva1, Yu. D. Sergeeva2, V. D. Volkova2, D. I. Stom3,4, V. A. Terekhova2
1A. N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia
2Lomonosov Moscow State University, Moscow, Russia
3Baikal Museum of SB RAS, Listvyanka, Russia
4Surgut State University, Surgut, Russia
Keywords: soil contamination, pathogens, antagonism, dual culture method, effective concentrations, hormesis
Abstract
The facts of an increase in the proportion of phytopathogenic forms of micromycetes in soils contaminated with heavy metals (HM) make it relevant to study the mechanisms of their resistance, which is important to choose effective phytopathogen control methods. The issues of interaction between metal-resistant phytopathogens and non-pathogenic species against the background of pollution remain no less relevant and need to be studied. In laboratory experiments with pure cultures of four fungal species (phytopathogenic strains Alternaria alternata and Fusarium oxysporum and non-pathogenic strains Trichoderma harzianum and Clonostachys rosea), the resistance to Cu, Zn, Pb cations, separately added to nutrient medium with different content of available carbon (sucrose), was studied. Colony growth, sporulation activity, and biomass accumulation were measured. The effective concentrations, resulting in 50 % inhibition of growth parameters (EC50), were calculated. The studied fungi showed different resistance to HM. T . harzianum and C. rosea were more resistant to Zn and Pb at any available carbon content. The pairs A. alternata-C. rosea and T. harzianum-C. rosea were the most resistant to Cu on media with lower and higher carbon contents, respectively. At the same time, Zn and Pb turned out to be less toxic than Cu for all fungi. The antagonistic activity, assessed by the dual culture method on media supplemented with HM cations, depended both on the growth characteristics and on the revealed resistance to HM. The activity of fast growing T. harzianum as a territorial antagonist was stimulated by the addition of Zn and Pb. The slow-growing C. rosea showed competitiveness due to its high resistance to HM. It is concluded that it is necessary to take into account species resistance to HM in order to predict the development of relationships between pathogenic and non-pathogenic species in fungal communities against the background of soil pollution.
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