Silver nitrate regulating phenolic acid and flavonoid accumulations in callus cultures of Aerva lanata, an important medicinal herb

In vitro cultures of the medicinal herb, Aerva lanata exhibited heterogeneity in diverse concentrations of (0.5-10 mg/l) silver nitrate. The texture of the callus tissue varied from friable, non-friable to nodular. Callus cultures also exhibited a color variation ranging from white, brown to black. Silver nitrate did not exhibit a significant variation in the accumulation of in vitro biomass at a concentration range of 0-5 mg/l. Higher concentrations were found inhibitory for callus growth. The cultures exhibited a positive correlation between silver nitrate concentration and accumulation of phenolics as well as flavonoids up to a concentration of 5.0 mg/l. The results generated clearly indicated that silver nitrate may be used as an additive for regulating the callus morphology, growth and accumulation of phenolic compounds under in vitro conditions.