Copper tolerance, protein and catalytic activity in phytopathogenic fungus alternaria alternata

Abstract

In vitro tolerance of soil borne phytopathogenic fungus i.e. Alternaria alternata in terms of growth, physiology and metal uptake capacity against different doses of copper [Cu(II)] metal was assessed. In preliminary growth experiments, nitrate, chloride and sulphate of Cu(II) were amended in seven different concentrations viz. 25, 50, 75, 80, 85, 90 and 100 ppm in nutritive agar medium along with fungus inoculum. Amongst three salts, the maximum inhibition in radial growth of the fungus was observed with increasing concentrations of copper salts in order of: CuSO4> CuNO3> CuCl2. Further trials were conducted in nutritive broth with four different concentrations (25, 50, 75 and 100 ppm) of copper sulphate to assess growth inhibition, metal accumulation, protein and catalase activity in the fungus biomass. It was found that fungus dry biomass was significantly declined by 70-99% along with net metal accumulation of 40% with increasing metal concentrations. Total protein contents and catalase activity was considerably increased up to 2-5 and 2-3 folds, respectively with increase in metal concentration from 25-100 ppm and incubation period from 48, 72 and 96 hours over control. Present study concludes that A. alternata was able to tolerate up to 90 ppm of copper, therefore it is imperative to consider fungus metal tolerance range during fungicide formulations.