Inhibition of @@iAspergillus flavus@ growth and detoxification of aflatoxin B@@d1@ by the medicinal plant zimmu (@@iAllium sativum@ L. x @@iAllium cepa@ L.)

摘要

Aflatoxins are carcinogenic, teratogenic and immunosuppressive secondary metabolites produced by @@iAspergillus flavus@ and @@iAspergillus parasiticus.@ Aflatoxin contamination of peanut is one of the most important constraints to peanut production worldwide. In order to develop an eco-friendly method of prevention of @@iA. flavus@ infection and aflatoxin contamination in peanut, aqueous extracts obtained from leaves of 30 medicinal plants belonging to different families were evaluated for their ability to inhibit the growth of @@iA. flavus@ in vitro. Among them the leaf extract of zimmu (@@iAllium sativum@ L. x @@iAllium cepa@ L.) was the only one that showed antifungal activity against @@iA. flavus@ and recorded 73% inhibition of @@iA. flavus@ growth. The antifungal activity of the zimmu extract was significantly decreased upon dialysis with a dialysis membrane having molecular cut off 12 kDa or autoclaving at 121^'C for 20 min or boiling at 100^'C for 10 min and recorded inhibition of 52, 16 and 21%, respectively. When @@iA. flavus@ was grown in medium containing zimmu extract the production of aflatoxin B@@d1@ (AFB@@d1@) was completely inhibited even at a concentration of 0.5%. When AFB@@d1@ was incubated with zimmu extract a complete degradation of AFB@@d1@ was observed 5 days after incubation. When the roots of zimmu were incubated in water containing 70 ng of AFB@@d1@/ml, a reduction (by 58.5%) in AFB@@d1@ concentration was observed 5 days after incubation. A significant reduction in the population of @@iA. flavus@ in the soil, kernel infection by @@iA. flavus@ and aflatoxin contamination in kernels was observed when peanut was intercropped with zimmu. The population of the fungal antagonist, @@iTrichoderma viride@ in the zimmu-intercropped field increased approximately twofold.