Evaluation of morpho-physiological growth parameters of tomato in response to Cd induced toxicity and characterization of metal sensitive NRAMP3 transporter protein

Cadmium (Cd) is a non essential and toxic heavy metal that gets incorporated in the soil ecosystem through several anthropogenic activities. The Cd contaminated soils might have devastating affects on seed germination, plant growth and development. In the present work, a comparative evaluation was made to determine and optimize the detrimental level of accumulated toxic Cd metal in the tomato (Solanum lycopersicum; CO-3 variety). The perturbed morpho-physiological, biochemical alterations and molecular responses following the Cd induced stress were found to maximum at 250 μM Cd with having the highest expression of LeNRAMP3 gene. The oxidative burst induced and cell death was visualized through histochemical analysis using Evans blue (cell death) and DAB staining (H2O2 accumulation). The structural modelling of metal transporter protein done through homology modelling was found to acquire typical helical configuration, and revealed the potential active site residues involved in metal chelation. The function of LeNRAMP3 was deduced based on the functional annotation of protein AtNRAMP3. The functional signaling network and evolutionary relationships for LeNRAMP3 were explored and predicted based on comparative genomics and proteomic studies using the interactome pathways available for AtNRAMP3. The study revealed that LeNRAMP3 metal transporters are activily involved in Cd translocation from root to leaves of tomato and sensitive at 250 μM Cd concentration in the tomato plants.