Kumar and Saritha

Effect of Pb on Starch content

The increase in the starch content might be caused by excessive α-amylosis of

the components. In our experiment significant increase of starch accumulation

by lead occurred by 14% to 54% in comparision with controls (Fig. 7). Highest

increase was observed in Eichornia fasiculata (54%) and lowest in Calotropis

procera (14%) compared to controls followed by Ipomea purpurea (18%), Bromus

tectorum (6%), Parthenium histocarpus (4%) and Anisomilius molabarica (2%).

Increased starch levels were directly proportional with high concentration of heavy

metal Pb. Nutrient deficiency and heavy metal toxicities are known to produce

starch accumulation within leaves (Vazquez et al., 1987). C ₄ photosynthesis when

compared to C ₃ allows fast biomass accumulation with high nitrogen and water use

efficiency (Leegood and Edwards 1996; Sage 2004) which is desired set of trait to

increase the productivity of crop plants (Matsuoka et al., 1998) may be the cause

for increase in starch and a required character for successful phytoremediation.

Similar findings were observed according to verma and dubey (2001) due to

cadmium toxicity in rice and in Tilia argentea and Quercus cerris by Tzvetkova

and Kolaro (1996). This may be due to higher resistance of their photosynthetic

apparatus and low starch export from the mesophyll.

From the results it has been clear that the concentration of Pb toxicity on the plants

posed high oxidative stress on activity of antioxidant enzymes and biochemical

compounds in weed plants and both played a vital role in combating oxidative

stress in plants for the plant susceptibility and tolerance. Among the plants

calotropis procera and Bromus tectorum are efficient in combating the oxidative

stress and accumulating higher amount of Lead than other species. Finally, data

which is generated through this study will be very helpful in finding high tolerant

plant species to thrive in high lead environments.

acknowledgement

Author wants to thank Dr K.V. Saritha, Biotechnology Department of the

Sri Venkateswara University, India for her technical assistance that enabled

successful execution of this study.

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Int. J. Bioinformatics and Biological Sci.: v.2 n.1&2, p. 13-22. March & June 2014