Pathogenicity and diversity of vegetative compatibility of Fusarium verticillioides

Pathogenicity of 10 Fusarium verticillioides isolates, originated from grain of wheat (five isolates) and maize (five isolates), were studied under greenhouse conditions. Based on different parameters of the pathogenicity estimate (a scale for % of nonemerged plants, % of survived plants, plant vigour - the growth and dry weight of roots and epicotyls and disease severity) it was determined that all F. verticillioides isolates expressed a different degree of pathogenicity. According to % of nonemerged plants six three and one F. verticillioides isolates expressed low, moderate and high degree of pathogenicity, respectively. All F. verticillioides isolates reduced the plant survival rate and vigour, while the disease severity ranged from 2.0 to 3.54. Two types of nit mutants, nit1 and NitM, were obtained by the use of the method of vegetative compatibility. The frequency of nit1 mutants was greater (58.79%) than the frequency of NitM mutants (5.77%). A total of 10 vegetative compatibility groups (VCGs) of F. verticillioides were established in the complementation tests. These results point out to a high genetic diversity of F. verticillioides population

Plesni i mikotoksini u zrnu kukuruza posle berbe

Incidence of toxigenic fungi (molds) and concentration of mycotoxin aflatoxin B1 (AFB1), deoxynivalenol (DON), zearalenone (ZON) and fumonisin (FB1) were studied in the maize grains collected immediately after harvesting in 2012. A total of 29 maize samples were analyzed and the highest incidence was determined for fungal species of Rhizopus (56.41%), Aspergillus (43.66%) and Fusarium (14.97%) genera. Significantly lower incidence was obtained for species of genus Penicillium (3.31%), and especially for species of genera Acremonium (1.38%), Alternaria (0.75%) and Cladosporium (0.14%). Among toxigenic fungi Aspergillus flavus (36.69%) was the most common species of Aspergillus genus, whereas the Fusarium verticillioides with 14.69% of incidence was the predominant species of Fusarium genus. In all studied maize samples, the presence of AFB1, ZON and FB1 mycotoxins was established, except for DON which was established in 75.86% samples. AFB1 was detected in average concentration of 13.95 μg kg-1 for 44.83% of samples, and average concentration higher than 40 μg kg-1 for 55.17% of samples. The average concentrations of DON which was detected was 235 μg kg-1, while it was 98.38 μg kg-1 and 3590 μg kg-1 for the presence of ZON and FB1, respectively. Moderate positive correlation was obtained between concentrations of AFB1 and FB1 (r=0.35), while weak positive correlation was established between concentrations ZON and DON (r=0.02).Učestalost toksigenih gljiva (plesni) i koncentracija mikotoksina aflatoksina B1 (AFB1), deoksinivalenola (DON), zearalenona (ZON) i fumonizina B1 (FB1) je proučavana u uzorcima zrna kukuruza prikupljenim odmah posle berbe u 2012. godini. U ispitivanih 29 uzoraka najveću zastupljenost imaju vrste iz rodova Rhizopus (56,41%), Aspergillus (43,66%) i Fusarium (14,97%). Značajno niža učestalost ustanovljena je za vrste roda Penicillium (3.31%), a posebno za vrste iz rodova Alternaria (0,75%) i Cladosporium (0,14%). Među toksigenim vrstama, A. flavus (36,69%) je bila najučestalija vrsta iz roda Aspergillus, dok je F. verticillioides sa prisustvom od 14,69% bila dominantna vrsta roda Fusarium. U svim ispitivanim uzorcima kukuruza ustanovljeno je prisustvo mikotoksina AFB1, ZON-a i FB1 (100%), osim DON-a koji je bio prisutan u 75,86% uzoraka. AFB1 je detektovan u prosečnoj koncentraciji od 13,95 μg kg-1 u 44,83% uzoraka i u prosečnoj koncentraciji od više od 40 μg kg-1 u 55,17% uzoraka. Prosečna koncentracija DON-a je bila 235 μg kg-1, ZON-a 98,38 μg kg-1 i FB1 3590 μg kg-1. Srednja pozitivna korelacija ustanovljena je između koncentracija AFB1 i FB1 (r=0,35), dok je slaba pozitivna korelacija utvrđena između koncentracija ZON-a i DON-a (r=0,02)

Distribucija plesni i mikotoksina u silaži od zrna kukuruza u silo-trenču

In this study the mycological and mycotoxicological contamination of maize silage samples collected from the bottom (BL), middle (ML) and top (TL) layer in the silage trench silo was studied. Mycological testing of the silage contamination showed the presence of five potential toxigenic fungi of the genera, Aspergillus, Fusarium, Mucor, Penicillium and Rhizopus with their total number ranging from 1 to 10 x 103 CFU g-1. Also, four mycotoxins were detected as followed, aflatoxin B1 (AFB1), zearalenone (ZON), deoxynivalenol (DON) and fumonisin B1 (FB1). Mycotoxins AFB1 and FB1 were detected as 100% positive in all the samples tested. An average concentration of AFB1 was 2.31 μg kg-1, 2.51 μg kg-1 and 2.81 μg kg-1 in BL, ML and TL respectively, while the concentration of FB1 was 1292.00 μg kg-1, 1298.00 μg kg-1 and 1902.00 μg kg-1 in BL, TL and ML respectively. Average concentration of toxin ZON in positive samples was 15.69 μg kg-1 in BL and 30.68 μg kg-1 in ML, while its presence in the samples taken from the top layer was not detected. An average concentration of DON toxin in positive samples were in the range of 41.71 μg kg-1 for TL, 79.20 μg kg-1 for ML, while it was 97.00 μg kg-1 for BL. There was no statistically significant correlation between moisture content and total number of moulds and concentrations of certain mycotoxins. However, statistically highly significant correlations between the total number of moulds and AFB1 concentration (r = 1.0), ZON (r = 0.99) and FB1 (r = 0.91) were established, while weak correlation was obtained in the case of DON and total mould counts (r = 0.54).U radu je ispitivana mikološka i mikotoksikološka kontaminacija uzoraka silaže od zrna kukuruza sakupljenih iz donjeg (DS), srednjeg (SS) i gornjeg (GS) sloja silaže u silo-trenču. Mikološkim ispitivanjima kontaminacije silaže ustanovljeno je prisustvo pet potencijalno toksigenih rodova plesni, Aspergillus, Fusarium, Mucor, Penicillium i Rhizopus sa ukupnim brojem od 1-10 x 103 CFU g- 1. Takođe, detektovana su i četiri mikotoksina kao što su aflatoksin B1 (AFB1), zearalenon (ZON), deoksinivalenol (DON) i fumonizin B1 (FB1). Mikotoksini AFB1 i FB1 detektovani su kao 100% pozitivni u svim ispitivanim uzorcima. Prosečna koncentracija AFB1 bila je 2,31 μg kg-1 za GS, 2,51 μg kg-1 za DS i 2,81 μg kg-1 za SS, dok je prosečna koncentracija FB1 bila 1292,00 μg kg-1 za DS, 1298,00 μg kg-1 za GS i 1902,00 μg kg-1 za SS. Prosečna koncentracija ZON toksina u pozitivnim uzorcima je 15,69 μg kg-1 za DS i 30,68 μg kg-1 za SS, dok njegovo prisustvo nije detektovano u uzorcima iz gornjeg sloja. Prosečna koncentracija DON toksina u pozitivnim uzorcima bila je od 41,71 μg kg-1 za GS, 79,20 μg kg-1 za SS do 97,00 μg kg-1 za DS. Nije utvrđena statistički značajna korelacija sardžaja vlage sa ukupnim brojem plesni i koncentracijom pojedinih mikotoksina. Međutim, utvrđena je statistički veoma značajna korelacija između ukupnog broja plesni i koncentracije AFB1 (r = 1,0), ZON (r = 0,99) i FB1 (r = 0,91), a nešto manja u slučaju DON i ukupnog broja plesni (r = 0,54)

Fusarium species and their mycotoxins in wheat grain

Incidence of fungi and concentration of mycotoxin deoxynivalenol (DON), zearalenone (ZON) and fumonisin (FB1) were studied in the grain of the winter wheat collected subsequently after harvesting in 2010. In the analyzed samples the highest incidence was determined for the species of Fusarium (84.7%) genus, significantly lower incidence was determined for the species of genus Alternaria (12.35%), and especially for species of genera Acremoniella (2.05%), Acremonium (0.65%) and Penicillium (0.25%). F. graminearum (99.05%) was the most present species of Fusarium genus, whereas the following species F. sporotrichioides (0.4%), F. subglutinans (0.4%), F. poae (0.05%), F. proliferatum (0.05%) and F. verticillioides (0.05%) were only sporadic. The presence of DON, ZON and FB1 mycotoxins was established in all studied wheat samples. DON was detected in concentrations from 123 to 393 μg kg-1 (average 214 μg kg-1), ZON from 157.144 to 471.055 μg kg-1 (average 299.934 μg kg-1), and FB1 from 2.715 to 16.488 μg kg-1 (average 6.286 μg kg-1)

The incidence of Pyrenochaeta terrestris in root of different plant species in Serbia

Root samples of cereals (oats, wheat, barley, maize and sorghum), vegetables (garlic, onion, pepper, cucumber, pumpkin, carrot and tomato), industrial plant (soya bean) and weeds (Johnson grass, barnyard grass and green bristle-grass) collected in different agroecological conditions in Serbia were analysed for the presence of Pyrenochaeta terrestris. The fungus was found in 42 out of 51 samples (82.4%), while the incidence varied from 2.5 to 72.5%. The highest incidence was detected in cereals (average 30.3%), and then in weeds of the Poaceae family (average 14.2%). Considering single species, maize (up to 72.5% in root) and Johnson grass (up to 37.5%) were mostly attacked by this fungus. The lowest incidence of the fungus was determined in vegetable crops (average 6.7%). Red to reddish discoloration of root was correlated with the incidence of the fungus. Obtained data indicate that P. terrestris is widespread in Serbia and conditions for its development are favourable. [Projekat Ministarstva nauke Republike Srbije, br. TR-31023

Fungal infections of Adonis vernalis L. fruits

Yellow pheasant´s Eye is a herbaceous plant from dry ressy areas. Owing to habitat destruction and over- collection for ornamental and medical purposes A. vernalis L. has became scarce in central and south Europe. The reasons for A. vernalis threatened are manyfold. The low seeds germination rate is significant. According to our investigation the main cause of fruit destruction is fungal infection. From the surface of the fruits, collected in Deliblato Sands, the following micromycetes has been isolated and determinated: Fusarium solani (Mart) Sacc., Fusarium sporotrichioides Sherb., Alternaria sp. and Drechslera sp. Histologycal analysis showed the presence of conidiomata and conidia Phoma sp. in the seeds

Frequency of toxigenic Fusarium species and fusariotoxins in wheat grain in Serbia

A total of 88 and 40 wheat samples collected immediately prior to harvest in 2005 and 2006, respectively, under different agroecological conditions, were studied in respect to the occurrence of Fusarium spp. and the production of fusariotoxins. The greatest number of samples was infected with species of the genera Fusarium (81.8 and 65.0%), and Alternaria (36.3 and 17.5%) with the intensity ranging from 9.4 to 84.0% in 2005 and from 23.4 to 80.6% in 2006. Out of 13 identified species belonging to the genus Fusarium, F. graminearum had the highest frequency (35.2 and 12.5%) and the intensity up to 67.2%, and 21.9%, in 2005 and 2006, respectively, followed by F. poae but only in 2005 (20.4%), and F. proliferatum in 2006 (19.7%). The natural occurrence of mycotoxins in positive samples varied from 37 to 331 ppb for zearalenone and from 31 to 125 ppb for diacetoxyscirpenol (DAS) and T-2 toxin. The concentration of mycotoxins amounted, on average, to 133.4, 61.0 and 45.7 ppb for zearelenone, DAS and T-2 toxin, respectively

The role of paecilomyces lilacinus (thom) samson and other fungal species in biodegradation of ochratoxin a

Nine isolates of fungi of genera Aspergillus, Fusarium, Paecilomyces and Penicillium were cultured on the modified Vogel’s medium with the addition of crude ochratoxin A (OTA) extract. This crude OTA extract was derived from a natural solid substrate on which Aspergillus ochraceus strain CBS 108.08 was cultivated. OTA was isolated, partially purified, dried by evaporating and dissolved in ethanol (1 mg ml-1), and added to the test medium up to the final concentration of 10 μg ml-1. The presence of OTA residues was determined after 7 and 14 day cultivation of fungi in the test medium at 27±1°C. The Paecilomyces lilacinus isolate (Inf. 2/A), which completely degraded OTA (150 μg) after only seven days, was selected for further studies. Wet sterile rice grains (50 g + 25 ml distilled water) were inoculated with individual isolates of fungi A. ochraceus (strain CBS 108.08) and P. lilacinus (isolate Inf. 2/A), and with their combination. In the case of P. lilacinus monoculture, 0.9 mg of crude OTA was also added into cultivation substrate. Each test was done in three replications. After the four week cultivation of individual and combined fungi at 27±1°C, inoculated rice grains were dried to the constant weight and pulverized. OTA was determined in these samples by the application of standard TLC method for fodder analysis. OTA in the amount of 61.310 μg kg-1 dry matter (DM) was determined only in the samples inoculated with a producer of ochratoxin A (A. ochraceus, strain CBS 108.08). On the other hand, a much smaller amount of OTA (80 μg kg-1 DM) was detected in samples inoculated with combined cultures of A. ochraceus and P. lilacinus isolates. Gained results indicate that P. lilacinus degraded, on average, 99.8% of OTA. After four week cultivation, the same fungal isolate in the samples of wet sterile rice kernels with the addition of 0.9 mg of crude OTA, completely degraded added crude OTA (<8 μg kg-1)