Mechanism of aflatoxin uptake in roots of intact groundnut (Arachis hypogaea L.) seedlings.

Aflatoxins are one of the most potent toxic substances that occur naturally, which enter agricultural soils through the growth of aflatoxigenic fungi in rhizhosphere and nonrhizhosphere soils. Though several reports regarding the uptake of aflatoxin by plants are available, the mechanism of aflatoxin uptake remains unknown. This study characterized the aflatoxin uptake mechanism by in vitro hydroponic experiments under variable conditions. The uptake reached saturation after 48 h of incubation for AFB1 and B2 and 60 h for AFG1 and G2. A linear increase in uptake with increasing aflatoxin concentrations was observed, and it fits both linear and nonlinear regression. AFB1 uptake was directly proportional to transpiration rate, and blocking aquaporin activity using mercuric chloride revealed its involvement in the uptake. None of the metabolic inhibitors used to block active transport had any effect on aflatoxin uptake except for sodium azide. From the present study, it could be concluded that aflatoxin uptake by groundnut roots followed mainly a passive way and is facilitated through aquaporins. The involvement of active component should be studied in detail.