Mercury (Hg) is one of the major toxic heavy
metals because it bioaccumulates and biomagnifies in
animal and human bodies via the food chain. To eliminate
heavy metal contamination, plants are being used as
removal agents of pollutants/toxic chemicals from the
environment. The present study was mainly focused on
elucidating the potential phytotoxic effects of Hg heavy
metal ion exposure on
Sesbania grandiflora
seedlings.
Growth of seedlings was significantly affected (56 %) at
60 mg L
-1 Hg concentration. The level of chlorophyll
pigment contents was increased in Hg-treated plants
compared to the control. Malondialdehyde content and
antioxidative enzyme activities were found to be significantly
increased by increasing the concentration of Hg
exposure up to 40 mg L
-1 while slightly decreased at
higher doses. The DNA alterations appearing in the random
amplified polymorphic DNA (RAPD) profiles of leaf
and root tissues following Hg heavy metal exposure
included the disappearance of normal DNA bands and the
appearance of new bands compared to the untreated controls.
This result strongly indicated that genomic template
stability was significantly affected by Hg-induced stress in
S. grandiflora seedlings. It is concluded that DNA polymorphisms
detected by RAPD fingerprinting analysis
could be used as potential molecular markers for the
evaluation of Hg heavy metal ion-induced genotoxic
effects in other plant species.
