Rhizosphere and rhizoplane of fababean (Vicia faba), melochia (Corchorus olitorius), sesame (Sesamum indicum) and soyabean (Glycine max) plants are inhabited with fungi, mostly Aspergillus flavus, A. niger, Fusarium oxysporum, Penicillium corylophilum, P. cyclopium, P. funiculosum and Rhizopus stolonifer. All fungal species have the ability to produce gibberellin (GA) but F. oxysporum was found to produce both GA and indole-acetic acid (IAA). The optimum period for GA and IAA production by F. oxysporum was 10 days in the mycelium and 15 days in the filtrate at 28°C. The contents of GA and IAA were significantly increased at 0.5 and 1% NaCl after 5 days, but they were lowered at 4% (700 mM) NaCl. Cytochrome P-450 was significantly increased under salt stress at 0.5-7% NaCl. Calcium decreased NaCl stress on F. oxysporum by significant elevating GA biosynthesis at 40 mM Ca 2+ /700 mM Na + . GA at 10 µM and Ca 2+ at 10 mM enhanced the germination of seeds under 175 mM Na + .Keywords: GA; IAA; cytochrome; fungi; calcium; salinityThe microbial synthesis of plant growth regulators (gibberellin and auxin) is an important factor in soil fertility (Kampert and Strzelczyk 1975). Gibberellin (GA) and indole-acetic acid (IAA) are secondary metabolites, which are important biotechnological products, produced commercially from fungi for the agricultural and horticultural industry (Deacon 1984, Bruckner 1992. GA was isolated from Gibberella fujikuroi by T. Yabuta and IAA was isolated from Rhizopus suinus by K.V. Thimann in 1935. GA 3 is the dominant component of the gibberellin complexes isolated from fungi (Bozhkova et al. 1991). It is now generally agreed that GA and IAA are very widely distributed throughout the plant kingdom.Salinity represents one of the most important factors exerting stress on fungal as well as plant cell metabolism. Kaur et al. (1998) found that GA 3 at 6µM concentration induced increased germination and seedling growth under salt stress. Calcium is particularly important nutrient in plants exposed to NaCl stress because of its role in maintaining the structural and functional integrity of membrane (Leopold and Willing 1984) and in cell wall extensibility (Taiz 1984).No recent study explains the ability of filamentous fungi, associated with roots of plant crops, for the GA and IAA production and their role toward the host plant crops. Also, no studies explain the effect of salinity on the activity of rhizosphere and rhizoplane fungi and role of Ca 2+ and GA in alleviation the salt stress. The present work was commenced by collecting four plant crops for isolation of both rhizosphere and rhizoplane fungi, and screening their efficiencies for GA and IAA production. Also, effect of salinity on GA, IAA and cytochrome P-450 biosynthesis by F. oxysporum was studied. The roles of GA and Ca 2+ in reversing the toxicity of salt stress effect in seedlings were also studied. MATERIAL AND METHODSCollection of samples. Ten samples of fababean (Vicia faba), melochia (Corchorus olitorius), sesame (Sesamum ind...

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Rhizosphere and rhizoplane of fababean (Vicia faba), melochia (Corchorus olitorius), sesame (Sesamum indicum) and soyabean (Glycine max) plants are inhabited with fungi, mostly Aspergillus flavus, A. niger, Fusarium oxysporum, Penicillium corylophilum, P. cyclopium, P. funiculosum and Rhizopus stolonifer. All fungal species have the ability to produce gibberellin (GA) but F. oxysporum was found to produce both GA and indole-acetic acid (IAA). The optimum period for GA and IAA production by F. oxysporum was 10 days in the mycelium and 15 days in the filtrate at 28 degrees C. The contents of GA, IAA and cytochrome P-450 were increased at 0.5 and 1% NaCl after 5 days, but GA and IAA were lowered at 4% (700 mM) NaCl. Calcium decreased NaCl stress on F. oxysporum by significant elevating GA biosynthesis at 40 mM Ca2+/700 mM Na+. GA at 10 microM and Ca2+ at 10 mM enhanced the germination of seeds under 175 mM Na+.

This work assesses the extent of patulin contamination in Penicillium expansum-infected apples stored at room temperature for short periods of time and its relationship with apple variety (Golden or Fuji), degree of ripeness and size of lesions. Inoculated apples were incubated at 20 degrees C. Patulin was determined in both sound and decayed tissue from cylindrical samples taken around the lesions and cut into 0.5-cm thick sections. Higher accumulation of patulin occurred in Golden apples, with less ripened apples showing higher concentrations. Total accumulated patulin was similar or higher in 4-cm compared to 2-cm lesioned apples, although a decrease in patulin concentration was observed in older lesion sections. Patulin accumulation occurred over a short period of time at room temperature, thus the stand-by period before processing should be minimised. Of total patulin, 2-6% migrated to the surrounding sound tissue, thus trimming tissue around the rotten part may be a good preventive practice for apple derivative production.