SEED-BORNE MYCOFLORA OF SOME SPICES. DETECTlON TECHNIQUES AND PATHOGENICITY

Seed samples of capsicum. coriander and fenugreek obtained from various countries of the world through the courtesy of The Danish Government In.3titute of Seed Pathology for Developing Countries, Copenhagen, Denmark were studied for the seed-borne mycoflora. Of the seed-borne fungi, at least 20 genera and 46 species on 222 samples of capsicum, 14 genera and 24 species on 88 samples of coriander and 10 genera and 14 species On 23 samples of fenugreek were isolated and identified. Capsicum seed from Pakistan, India, Turkey, Nigeria and Ghana; coriander from Pakistan and India and fenugreek from Syria Showed maximum infection of seed-borne mycoflora along with certain\ unidentified yeasts and bacteria. Capsicum showed a more abundant and Varied mycoflora than coriander and fenugreek. The genera frequently isolated were Alternaria, Ascochyta, Botrytis, Botryodiplodia, Cephalosporium, cercospora,Colletotrichum,Corynespora, Curvularia, Drechslera, Epicoccum, Fusarium, Gerlachia, Macrophomina, myrothecium,Nigrospora,Pestalotia,Phoma.PhOmopsis,Sclerotium, Stemphylium,Ulocladium and Verticillium. Of the different species Alternaria alternata and Fusarium moniliforme were predominant. Storage fungi like Aspergillus,Penicillium and Rhizopus were rarely found except in a few heavily infected samples. Whereas the seed-borne mycoflora of coriander and capsicum were similar, Phoma multirostrata, protomyces. macros porus and Pythium spinosum were observed on coriander alone.Colletotrichun. capsici was the only well-known pathogen of capsicum obtained. Chlamydospores of P.macrosporus were found on fruits of coriander and the possibility of the presence of stem-gall disease caused by P. macrosporus in Pakistan is discussed.F. OIoniliforme, F. solani and F. oxysporum on fenugreek and Phoma multirostrata and pythium Spinosum on coriandgr are new seed borne fungi not hitherto reported. In pathogenicity experiments F. moniliforme, F. solani and F. oxysporum caused seed not and wilting of the seedlings of capsicum and fenugreek whereas F. solani caused seed not and wilting of seedlings of ccriander.A simple Thin Layer Chromatography (TLC) technique was used to Investigate mycotoxins and other secondary metabolites. Some of the toxins detected were also confirmed by High Performance Liquid Chromatography (HPLC). Of the 1104 isolates of F. moniliforme, F. solani, F. oxysporum, F. semitectum, F. equiseti and F. subglutinans used for the detection of mycotoxins and secondary metabolites,zearaLenone and zeara1enol were detected from F. moniliforme, F.semitectum and F. equiseti whereas an unidentified metabolite presumably belonging to the zearalenone family was also detected from isolates of F. moniliforme and F. equiseti. Other well-known mycotoxins like moniliformin and vomitoxin (deoxynivalenol) were found in F. moniliforme.Equisetin, an antibiotic and a mild toxin, has been reported here for the first time from several isolates of F. semitectum. No toxin could be detected from F. oxysporum, F. subglutinans or F. solani. Among the other secondarymetabclites,bostrycoidin andfusrubin from F.solani and anhydrofusarubin and bostrycoidin from F.moniliforme are also reported.Apart from macro- and micromorphological characters used for the identification of species of Fusarium, a simple dichotomous key has been proposed for the identification 0f the 6 species viz.,F. moniliforme, F.solani,F.oxysporum,F.semitectum,F.Equiseti and F. subgiutinans. The key is based on the TLC profiles of secondary metabolites of Fusarium spp., and their growth response to the presence of tannin. The importance of the use of several substrates For mycotoxin production is also discussed