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    Determination of seedborne fungi in onion and their transmission to onion sets
    (Priel Publ, 1997) Koycu, ND; Ozer, N
    Samples of onion (Allium cepa L.) seeds were obtained from seven regions in Turkey. The seed coat, embryo and endosperm were cultured, the seedborne fungi were determined and their transmission to onion sets was investigated in both sterile and field soils. Among the fungi determined, Aspergillus alutaceus Berk, and Curt., Beauveria bassiana (Bals.) Vuill., Cladosporium cladosporioides (Fres.) de Vries, Geotrichum sp., Humicola fuscoatra Traaen, Trichoderma harzianum Rifai and T. pseudokoningii Rifai in onion seeds, and Fusarium culmorum (W.G.Sm.) Sacc., F. graminearum Schwabe and F. sambucinum Fuckel in onion sets, were recorded for the first time. Aspergillus niger v. Tieghem was found at the highest rate in seed samples (especially in the seed coat), and in bulbs and roots of onion sets that developed from these seeds, whether in sterile or field soil. Fusarium oxysporum Schlecht was isolated at a higher rate from onion sets grown in sterile or field soil, than from seeds. F: acuminatum Ellis and Everhart, F. sambucinum, F. equiseti (Corda) Sacc. and F. graminearum were isolated only from onion sets grown in sterile soil. In dual culture tests, these Fusarium isolates were inhibited by A. niger and thus, except for F: oxysporum, could not develop in agar plate. The Fusarium spp. appeared-in onion sets grown in sterile soil and were inhibited by other fungi infield soil. It was concluded that all fungi were seedborne and that A. niger and Fusarium spp., but not the other fungi, were transmitted from the seeds to onion sets. A. niger and F. oxysporum were also transmitted through the soil.
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    Intracellular superoxide dismutase, catalase, and glutathione peroxidase activities and membrane lipid peroxide levels in Fusarium acuminatum upon environmental changes in a defined medium
    (Elsevier Science Inc, 2002) Ayar-Kayali, H; Ozer, N; Tarhan, L
    The variations of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities and lipid peroxide (LPO) levels in Fusarium acuminatum, an aerobic filamentous fungus, were investigated depending on the carbon and nitrogen sources during the incubation period. Fungus was cultivated in growing medium containing either maltose or saccharose in 5-25 g/L concentration range as a carbon source and either glycine or peptone in 5-35 g/L concentration range as a nitrogen source at 28 degreesC and 100 rpm. The observed highest SOD, CAT, and GSH-Px activities were 31.2 +/- 0.655, 62.5 +/- 5.23, and 1.52 +/- 0.0122 IU/mg in the presence of 20 g/L maltose and 73.96 +/- 1.48, 74.46 +/- 2.94, 3.48 +/- 0.083 IU/mg in the 15 g/L glycine-containing medium at 16 days, respectively. At the same time, the minimum LPO level was observed at 20 g/L maltose and 15 g/L glycine compared with the other carbon and nitrogen sources. The results showed a negative correlation between antioxidant enzyme activities and membrane LPO levels in F. acuminatum cells. (C) 2002 Elsevier Science (USA). All rights reserved.