Karolina Vrandečić

The functioning of soil ecosystems greatly depends on the interactions occurring between soil biota communities. It is well known that earthworms are an important soil component that substantially affects its function, including their meaningful impact on the development of different phytopathogenic soil fungi. Phytopathogenic fungi are responsible for crop disease and cause great economic damage. It has previously been established that earthworms’ coelomic fluid can suppress the growth of phytopathogenic fungi, but the exact molecular mechanism is unknown. The present study aimed at broadening the proof of this observed phenomenon by investigating the effects of the coelomic fluid extract of three different earthworm species (Eisenia andrei, Dendrobaena veneta and Allolobophora chlorotica) on the growth of six different phytopathogenic fungi species (Berkeleyomyces basicola, Fusarium culmorum, Globisporangium irregulare, Rhizoctonia solani, Macrophomina phaseolina, and Sclerotinia sclerotiorum). Coelomic fluid extract was obtained by electrostimulation or usage of extraction buffer (only in case of A. chlorotica) and prepared in three different concentrations by diluting the obtained coelomic fluid with physiological saline. The coelomic fluid extract of the three investigated earthworm species had an inhibitory effect on the growth of all six phytopathogenic fungi species. The greatest inhibitory effect was achieved with the E. andrei coelomic fluid extract reducing the growth of R. solani fungi. The findings of this research confirm the antifungal activity of coelomic fluid obtained from earthworm species belonging to different ecological categories and may be of potential use in crop protection against phytopathogenic fungi.

The quaternization reactions of nicotinamide, with different electrophiles: methyl iodide and substituted 2-bromoacetophenones (4-Cl, 4-Br, 4-H, 4-CH₃, 4-F, 4-OCH₃, 4-Ph, 2-OCH₃, 4-NO₂) are reported. The preparations were carried out by conventional synthesis and under microwave irradiation in absolute ethanol and acetone. The synthesis performed by microwave dielectric heating significantly improved yield, up to 8 times, and shortened down the reaction time from ca. one day in conventional, to 10–20 min. The structures of the synthesized compounds were confirmed by IR, ¹H- and ¹³C-NMR spectroscopy, mass spectrometry and elemental analysis. The compounds have been screened for antifungal activities against Fusarium oxysporum, Fusarium culmorum, Macrophomina phaseolina and Sclerotinia sclerotiorum at concentrations of 10 µg/mL and 100 µg/mL. Six compounds showed the strong inhibition of mycelium growth at a concentration of 10 µg/mL. All tested compounds revealed the great inhibitory activities against S. sclerotiorum at a concentration of 100 µg/mL.

Wilted soybean plants (Glycine max (L) Merr.) were observed in May and June 2014, in commercial fields at Osijek and Vinkovci, Slavonia County, respectively. Affected plants were at the V3 crop developmental stage (Licht 2014) at Osijek and R1 stage at Vinkovci. Disease was observed on approximately 20% of the plants in the examined fields. Symptoms of the disease observed were external and internal browning at the base of stems, interveinal chlorosis of leaves, wilting, and death of shoots. Roots appeared healthy. Isolations of the pathogen were made from the discolored stem tissues that were previously sterilized with 1% sodium hypochlorite and then placed on potato dextrose agar (PDA). Colonies grown on PDA were carmine red with white margins and red pigments were produced in agar. The isolated fungi were transferred to carnation leaf agar (CLA) to induce sporulation. Macroconidia were unequally curved, 4- to 6-septate with foot-shaped basal cell and slender apical cell. Morphology of colonies and coni...