Copper induced suppression of systemic microbial contamination in Erythrina variegata L. during in vitro culture

Latent infection is one of the major problem encountered in plant tissue culture, with no effective solution available so far. It is responsible for huge losses in terms of time, effort and money both in industrial and scientific laboratories. In the present investigation, we have used copper sulfate (CuSO4) for effective control of latent infection in cultures of Erythrina variegata, without compromising on the growth of the culture. Culture media MS + BA (5.0 μM) + NAA (0.5 μM) were supplemented with different concentrations of CuSO4, among the evaluated concentrations, 10.0 μM was found to be most suitable. The adventitious shoots produced per explant, average shoot length and chlorophyll content, increased in cultures growing on optimized CuSO4, also, instances of endogenous infection were significantly reduced, but no signs of toxicity in plants could be detected. However, at higher concentration (>10 μM) of copper, albeit, infection was suppressed more effectively but the growth of plant was severely affected, recording significant reduction in numbers of shoots per explant, average shoot length and chlorophyll content. The results obtained demonstrate that copper optimization in plant tissue culture media provides twofold benefits; not only it improves the shoot multiplication rate and growth of the cultures, but, also effectively controls the problem of endogenous infection with no cytotoxicity.