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This is the first report on the detection of fumonisin B1 (FB1) in Fusarium-infected adzuki bean (Phaseolus angularis) and mung bean (Phaseolus aureus). The infected beans had either a mouldy appearance or a distinct discoloration. Seed coats of infected adzuki beans changed from dark red to light red and those of mung beans from green to dark or brownish green. Fusarium spp. isolated from mouldy and discoloured beans included F. avenaceum, F. culmorum, F. equiseti, F. graminearum, F. moniliforme, F. oxysporum, F. solani, F. sporotrichoides and a few unidentified species. Healthy beans without any apparent discoloration and diseased beans with discoloration and mouldy appearance were analysed for mycotoxins. Diacetoxyscripenol, deoxynivalenol and T-2 toxin (T-2) were not detected in either healthy or discoloured adzuki and mung bean samples by thin layer chromatography (TLC). FB1 was detected by TLC in discoloured adzuki and mung bean samples but not in the healthy samples. TLC results were confirmed by high performance liquid chromatography (HPLC). The quantification of FB1 by HPLC revealed that discoloured adzuki and mung bean samples contained 261 +/- 43.8, and 230 +/- 21.6 micrograms g-1 of FB1, respectively. This investigation emphasizes the need for more detailed research in dealing with possible mycotoxin contamination in various foodstuffs including legumes.

This is the first report on the discovery of several mycotoxins in naturally infected mouldy navy beans (Phaseolus vulgaris L.) with distinct whitish grey to pink discoloration. Species of Fusarium isolated from the mouldy beans included F. avenaceum, F. culmorum, F. graminearum, F. moniliforme, F. oxysporum, F. solani and two Fusarium spp. Three types of bean samples were analysed for mycotoxins: (a) health beans without any apparent discoloration, (b) beans with pink discoloration, and (c) a mixture of beans with whitish grey and pink discoloration. The results indicated that diacetoxyscripenol (DAS), deoxynivalenol (DON), T-2 toxin (T-2) and fumonisin B1 (FB1) were present in type B and C samples but not in the healthy type A samples. Quantification of DAS, DON, and T-2 and of FB1 were achieved by gas chromatography and high performance liquid chromatography, respectively. The results showed that DAS, DON, T-2 and FB1 were not evident in the healthy samples, but in type B and type C samples, DAS, DON, T-2 and FB1 in the amounts of 9.2, 6.5, 5.5 and 0.5 microgram/g, and of 3.3, 3.1, 13.5 and 1.1 micrograms/g, respectively, were detected. Further research is under way to determine which species of Fusarium is responsible for the production of specific toxins.

The average percentage of fungal infection in twenty bean and soybean lots was determined by visual inspection (24.5 and 16.8%, respectively), and by laboratory isolation (58.5 and 33.7%), respectively. The mycoflora were more diverse in bean than soybean. Bean was more susceptible to fungal infection than soybean under similar environmental and cultural conditions. The most frequently isolated fungal genera for bean and soybean were Aspergillus, Penicillium, Rhizopus, Eurotium and Curvularia. Aflatoxins were not detected in the non-infected beans and soybeans, but aflatoxins (B1, B2, G1 and G2) were detected in the infected beans but not in the infected soybeans. The absence of aflatoxin in the fungal infected soybeans is discussed.

The plasma membrane of sporangiospores (spores) of Phycomyces blakeleeanus has distinct structural features that distinguish it from the plasma membrane of the sporangiophores. The plasma membrane of the spores is, however, derived from that of the sporangiophore. A study of sequential development of spores shows that the mass of cytoplasm in a sporangial initial is cleavaged by proliferation and subsequent anastomosis and membrane fusion of the clevage vesicles. The plasma membrane of the cleavage vesicles has a reversed curvature (inside out) to that of the sporangial plasma membrane. Otherwise, the distribution of intercalated membranous particles (Imp) on the fractured faces is similar to that of the plasma membrane of the sporangium. Lather, as a result of fusion of cleavage vesicles, curvature of the plasma membrane in the spore initials returns to their original state. In the processes of spore maturation, a new type of structural feature appears in the plasma membrane, which is not present either in the plasma membrane of spore initials or in the plasma membrane of sporangiophores or mycelia. This feature often is seen as large particles (30--35 nm) which are randomly distributed on the exoplasmic face (EF) with corresponding depressions on the plasmic half (PF) in freeze-fractured replicas. They increase in number with increasing spore maturity. These particles are, in fact, the inward protrusions of the plasma membrane of the spore. A change in the number of 5--8 nm intramembranous particles on the fractured faces is also noted during spor maturation, with an increase on the EF face and a corresponding decrease on the PF face. This alteration may result from vertical movement of Imp or from a change in the fracture plane as a consequence of alteration in the lipid content during maturation.

The multinucleate state of the vegetative spores of Phycomyces blakesleeanus arises as a consequence of cleavage of cytoplasm containing a variable number (1-6) of pre-existing nuclei. No nuclear division or incorporation of 3H-thymidine was detected during maturation of the spores.