大豆豆粒中一个能抑制黄曲霉毒素积累的生物化学机制

A BIOCHEMICAL MECHANISM THAT SUPPRESSES AFLATOXIN ACCUMULATION IN SOYBEAN SEEDS

具有萌芽能力的正常大豆豆粒和经过热处理灭活的豆粒,在接种黄曲霉毒素产生菌后,尽管菌体生长和产孢情况在二种豆粒上未见有何差异,但黄曲霉素B_1在前者中的积累速度显著低于后者。毒素产生菌的液体培养试验表明,即使是浓度低于从正常豆粒在接种培养后所检出到的大豆保卫素,它对菌体的生长虽然影响不大,但能使毒素的积累速度降低70%以上。据此推测,大豆受侵后能够激发产生大豆保卫素这一机制,至少是在一般条件下大豆出现黄曲霉毒素污染的情况较为少见的部分原因。

Despite the fact that growth and sporulation of toxigenic strain of Aspergillus flavus on inoculated viable and non-viable soybean seeds do not have any evident difference, the rate of Aflatoxin B_1 accumulation in viable seeds is much lower than that in non-viable ones. Results of studies with liquid cultures of A. flavus demonstrated that the presence of glyceollin, at a concentration even lower than that detected in inoculated viable seeds, could reduce the rate of Aflatoxin B_1 accumulation and its maxinum level by more than 70%, while its effect on mycelial growth was rather limited. Based on this finding, it is inferred that under normal conditions the infrequent occurance and comparatively low level of aflatoxin contaminations in soybean seeds might be at least partly due to the elicitation of glyceollin production when they are being attacked.