Effect of copper, nickel and lead on callus growth dynamics of Solanum lycopersicum

Solanum lycopersicum cv. (Punjab Kesar Cherry) (Tomato) belonging to family Solanaceae has been priced for the presence of lycopene, low sugar content and curative properties. However, the productivity of tomatoes has been observed to be low due to both biotic as well as abiotic stress. Considering the toxicity of copper (Cu), lead (Pb) and nickel (Ni) as environmental contamination and the economic importance of S. lycopersicum, the present study was undertaken to investigate the effects of these heavy metals on various growth parameters of callus cultures and plantlet regeneration. Callus induced through nodal segments was inoculated on Murashige and Skoog medium containing different concentrations (0 µM, 50 µM, 100 µM, 200 µM, 300 µM, 400 µM and 500 µM) of copper, lead and nickel. Decrease in different growth parameters was observed as 91.66-16.66 %, 76.38-11.11 %, 81.94-13.88 % for percent callus survival,  90.90-25 %, 72.72-37.50 %, 79.66-20 % for percent callus multiplication, 79.54-0 %, 82.75-33 %, 63.8-50 %  for percent root regeneration and 73.33-33 %, 72.50-33 %, 79.6- 20 % for percent shoot generation with increasing concentrations of Cu, Pb and Ni, respectively. Decrease in the average fresh and dry weight of callus was observed for all the metals. The order of toxicity was observed as Pb > Ni > Cu at the highest concentrations used for treating S. lycopersicum. The present study revealed that all three metals induced stress in the studied plant and need attention to developing methods to mitigate the consequences of metal toxicity in crop plants.
 