In vitro high frequency direct root and shoot regeneration in sweet potato using the ethylene inhibitor silver nitrate

The role of silver nitrate in the regulation of direct root and shoot regeneration from various explants of sweet potato ( Ipomoea batatas L.) was studied. A rapid and high frequency direct shoot regeneration procedure was achieved from stem and lamina explants. The magnitude of the response to silver nitrate varied among different explants and silver nitrate was found to have a significant effect on shoot regeneration. The best shoot regeneration was achieved from stem explants cultured on basal MS medium supplemented with 1.0mg l − 1 NAA without silver nitrate, with the regeneration frequency reaching 86.3%. With the addition of 8.0mg l − 1 silver nitrate on MS medium, 73.3% of lamina explants could directly regenerate shoots. Our study suggests that the addition of silver nitrate can promote shoot regeneration from various explants. The established procedure enables the production of a large number of plantlets within a short time, and thus can be used for assisting conventional breeding programmes and gene transfer studies.