Antifungal activity of macrofungi extracts on phytopathogenic fungal strains of genera Fusarium sp. and Alternaria sp.

Abstract

During the last decades, intensive application of synthetic fungicides in the agricultural crop protection practice caused growing concern for the existence of toxic chemical residues in food as well as in the whole environment. Instead of using synthetic fungicides, it is suggested that crop protection be carried out by using preparations based on compounds of natural origin (secondary metabolites of plants or microorganisms, including macrofungi from Basidiomycota) as biological control agents. The potential of macrofungal species as biocontrol agents was analyzed in this investigation of eight autochthonous species from different locations in Serbia. Both the terricolous species: Coprinus comatus, Coprinellus truncorum, Amanita strobiliformis, Hydnum repandum and the lignicolous species: Flammulina velutipes, Stereum subtomentosum, Trametes versicolor and Bjerkandera adusta were examined, with an aim to detect some novel sources of antifungal agents. This study surveyed antifungal activity of selected macrofungal extracts (MeOH, EtOH and CHCl3) against phytopathogenic Fusarium and Alternaria strains isolated from garlic, soybean and rice: F. proliferatum, F. verticillioides, F. proliferatum, F. graminearum and A. padwickii. Microdilution method in 96 well micro-plates was applied for the estimation of antifungal effects of macrofungi extracts in the range from 24.75 to 198.00 mg/ml and determination of minimal inhibitory (MIC) and minimal fungicidal concentration (MFC). EtOH extract of mychorhizal species H. repandum showed antifungal activity against all analyzed phytopathogenic strains, with the strongest effect on Fusarium strains (MIC 24.75 mg/ml; MFC 24.75 mg/ml). Among others, MeOH extracts of S. subtomentosum and C. micaceus showed similar effects while only B. adusta showed slight effect on Fusarium strains (MIC 24.75-99.00 mg/ml; MFC 24.75-99.00 mg/ml) and none effect on A. padwickii. The obtained results indicate the possibility of using examined extracts as efficient antifungal agents and provide the basis for the new formulations of biocontrol agents against phytopathogenic fungi in the future.

Tokom poslednjih decenija intezivna primena sintetičkih fungicida u zaštiti poljoprivrednih useva izaziva sve veću zabrinutost ljudi zbog prisustva toksičnih hemijskih ostataka u prehrambenim proizvodima kao i celoj okolini. Umesto korišćenja sintetičkih fungicida, preporučuje se da se zaštita useva vrši korišćenjem preparata na bazi jedinjenja prirodnog porekla (sekundarni metaboliti biljaka ili mikroorganizama uključujući i makrogljive iz razdela Basidiomycota) kao agense biološke kontrole. U ovom radu istraživan je potencijal agenasa biološke kontrole za osam autohtonih vrsta makrogljiva s različitih lokaliteta u Srbiji. Obe, terikolne vrste: Coprinus comatus, Coprinellus truncorum, Amanita strobiliformis, Hydnum repandum i lignikolne vrste: Flammulina velutipes, Stereum subtomentosum, Trametes versicolor i Bjerkandera adusta su istražene s ciljem da se otkriju neki novi izvori antifungalnih agenasa. U okviru ovog rada istražena je antifungalna aktivnost odabranih ekstrakata makrogljiva (metanolni, etanolni i hloroformski) protiv fitopatogenih sojeva Fusarium i Alternaria izolovanih s belog luka, soje i pirinča: F. proliferatum, F. verticillioides, F. proliferatum, F. graminearum i A. padwickii. Za procenu antifungalnog efekta ekstrakata makrogljiva upotrebljena je mikrodiluciona metoda mikrotitar pločama s 96 velova u opsegu koncentracija od 24,75 do 198,00 mg/ml i determinaciju minimalne inhibitorne (MIC) i minimalne fungicidne koncentracije (MFC). Etanolni ekstrakt mikorizne vrste H. repandum pokazao je atifungalnu aktivnost prema svim analiziranim fitopatogenim sojevima, sa najjačim efektom prema sojevima Fusarium (MIC 24,75 mg/ml; MFC 24,75 mg/ml). Između ostalog, sličan efekat pokazali su i metanolni ekstrakti S. subtomentosum i C. micaceus, dok je samo B. adusta imala blagi efekat na sojeve Fusarium (MIC 24,75-99,00 mg/ml; MFC 24,75-99,00 mg/ml), ali ne i na A. padwickii. Dobijeni rezultati ukazuju na mogućnost korišćenja ispitanih ekstrakata kao veoma efikasnih antifungalnih agenasa i samim tim oni predstavljaju osnovu za nove formulacije biokontrolnih agenasa protiv fitopatogenih gljiva u budućnosti.