Molecular Plant Breeding 2015, Vol.6, No.14, 1
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Table 2 FTIR detected changes in absorption bands of protein, lipid and carbohydrate under Cd induction
Absorption band (cm
-1
)
System
Bands of the sample
Control (C)
50 µM Cd 100 µM Cd 200 µM Cd 200 µM Cd+2 mM Spd
1800-1500
Protein
1652.93
1652.48
1652.50
1652.41
1652.99
3000-2800
Lipid
3401.42
3401.57
3402.75
3400.50
3339.83
1200-1000
Carbohydrate
1060.52
1061.43
1053.95
1025.62
1055.56
for hyper-accumulating property of any plant species
at least initially. In fact, the plant species remains
in some sort of disadvantageous condition by losing
out essential elements like K
+
. This was confirmed
with a typical EDAX spectrum in comparison with
varying Cd concentrations against control (Figure
1a-1e). Thus, in the present experiment,
Marsilea
observed a depletion of K
+
by 67.34 %, 94.94% and
95.58% in 50, 100 and 200 µM Cd concentration
respectively as compared to controlled condition
(Figure 1a-1e). However, the plants had recovered the
K
+
content by 6.6 % with Spd application. This could
be related for the interaction of some transporter/
channel proteins for ion binding as evident from other
studies dealt with polyamines in relation to metal
scavenging activities (Minocha et al., 2014). When
maize roots were allowed to adsorb Pb ion under
biodegradable chelating compounds, a significant
comeback or recovery of other essential ions was
observed (Fernando et al., 2007). Therefore, those
biodegradable compounds behaved a good source of
chemical elicitors for mitigation of heavy metal
bio-accumulation. In the present case,
Marsilea
plants
were also well responded to spermidine as elicitors to
reduce the metal adsorption as well as loss of K
+
in
result.
In conclusion, it is very clear that metal gets
bio-adsorbed following interaction strongly with some
functional groups. Thus, modification of cell wall
takes place in such a way that undergoes irreversible
damages.
Marsilea
plant being exclusively aquatic in
nature have by now been reported a noticeable amount
of heavy metal quenching ability (Lemoine et al.,
2013). Therefore, the results of the present investigation
may speculate that plants reacting with heavy metals or
toxic ions are preliminary accomplished by the
modification of cell wall, ion sequestering, binding
with organic acids and peptide groups etc. This
suggests a possible way for alleviation or mitigation
of Cd toxicity, however, mostly offered in hyper-accu-
mulating plant species. Thereby a fair chance for Cd
removal in
Marsilea
plants do also exist as like other
related aquatic plant species (e.g. water hyacinth)
from organometallic pollutants in water bodies
(Murithi et al., 2014). Taking all together, the changes
of functional groups in chemical residues could be
hypothesized for possible modification of cell wall to
Cd toxicity. Thereby
Marsilea
plant could be assumed
as an effective biomass for phytoremediation purposes. In
addition, FTIR analysis coupled with EDAX study
become evident as a potential tool for bio-adsorption
analysis in plant species even in non-angiospermic
plants like that of
Marsilea minuta
(L).
Materials and methods
Experimental treatments
Marsilea minuta
L., was collected from ponds of
University of Kalyani, Nadia having different micro
and macro vegetations in the monsoon season. The
plants were acclimatized in normal water for 7 days
under ambient condition. For the experiments of
EDAX and FTIR,
Marsilea
plants were grown in
nutrient solution with one fourth strength of MS
(Murashige and Skoog) media for 7 days supplemented
with various concentrations (0, 50, 100 and 200 µM)
of cadmium chloride (CdCl
2
) in different sets with at
least four replications (Murashige and Skoog 1962)
Another set was done with 2 mM spermidine (Spd)
with 200 µM of CdCl
2
solution. All the sets were
incubated for 7 days in growth chamber with
temperature of 37±1°C, 85% relative humidity and 14
h light (irradiance 72-80 µM/m
2
/s) and 10 h in dark.
After completion of the incubation period, SEM,
EDAX and FTIR experiments were done following
the processes mentioned below. Statistical analysis
was done with three replication per treatment on
plants and was computed adopting the conventional
ANOVA analysis.
Biosorption studies
For Biosorption, two types of plant materials like
fresh and oven dried powder were taken in equal
amount (2.0 g). For dried material, the plants were
