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.