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PURIFICATION OF PHYTOTOXIN FROM CULTURE FILTRATES OF FUSARIUM OXYSPORUM f.sp. CICERIS AND ITS BIOLOGICAL EFFECTS ON CHICKPEA

IFTIKHAR A. KHAN, S. S. ALAM AND *A. JABBAR

Abstract: Fusarium oxysporum f. sp. ciceris was grown on liquid minimal medium for the production of culture filtrates. Highest phytotoxic activity was extracted by petroleum spirit while n-hexane could not recover any toxicity from culture filtrates. The fungal bioassay revealed that different solvent extracts yielded 5 different inhibitory zones and for the recovery of maximum toxicity from culture filtrates, extraction with petroleum spirit followed by ethyl acetate should be done. Chloroplast assay revealed 6 different active bands in different solvent extracts. No solvent extracted the major compound extracted by petroleum spirit at Rf value 0.60. Two phytotoxic compounds 1 & 2 were purified from culture filtrates of FOC, which caused wilting and leaf burning of chickpea cuttings. The culture filtrate of FOC inhibited the synthesis of chlorophyll 'a' and 'b' of both chickpea varieties which might be responsible for the yellowing/chlorosis of leaves. The inhibition was more prominent in Aug-424 susceptible as compared to CM 98 resistant cultivars. The culture filtrates of FOC reduced the root length of germinating seeds of chickpea and might also be major factor for effecting the germination of seeds in wilt-infested soils.
 

Phytopathological Chemistry Lab., NIAB, Jhang Road, Faisalabad, Pakistan.
Chemistry Department Islamia University, Bahawalpur, Pakistan.