Function of enzyme lactate dehydrogenase in relation with lipid and glucose in biotic and abiotic stresses in the seedlings of Vigna radiata

Soil contamination by heavy metals has caught our consideration to assess and determine the cumulative effect of isolated bacterial strain of Pseudomonas stutzeri with copper (Cu) as a bioactive element in seed germination of four days old Vigna radiata. Effects of varying concentrations of essential trace metal on the germination of seeds (bioassay) were also taken into consideration. An important function of the enzyme lactate dehydrogenase (LDH) was observed in the shoots of four days old seedlings of V. radiata,cultivated in a series of experiments in the presence and absence of biotic and abiotic stresses simultaneously and separately. The data suggested that P. stutzeri separately inhibited the seed germination possibly due to the marked decrease in lipid contents whereas high LDH activity and high glucose contents as compared to the control ones indicated that high LDH activity was linked with elevated energy demand to overcome the stress for germination of seeds. Unexpectedly, germination of seeds was favoured with increasing concentrations of Cu (100 ppm) with P. stutzeri simultaneously, although both biotic and abiotic seemed to be toxic separately. No microbial life at the highest concentration of Cu showed that it was toxic to the bacterial strain, but normal growth of seedlings suggested that dead mass of P. stutzeri was effective for the adsorption of the Cu on their surface due to which Cu mobility was checked resuming the normal activity of LDH and glucose contents that believed to be at the cost of lipid contents. A suitable mechanism consistent with the finding has been proposed.     Key words: Pseudomonas stutzeri, Cu, lactate dehydrogenase (LDH), lipid, glucose