Optimization of Plant Regeneration from Long Term Embryogenic Callus Cultures of Pennisetum purpureum Schum. (Napier grass).

The effect of subculture interval and total culture age on plant regeneration from serially subcultured, leaf derived embryogenic callus cultures of Pennisetum purpureum (Napier grass) was determined. During 38 weeks of culture both embryogenic callus proliferation and the yield of plants was maximal for callus from frequently (about 2 weeks) subcultured cultures. Infrequent subculture (3-4 weeks or longer) greatly increased the proportion of soft and necrotic callus and severely reduced plant regeneration. A decline in regenerative capacity of a frequently subcultured stock after 30 weeks in culture was partially restored by treatment with ABA, or extended incubation. Plant regeneration was via the formation of somatic embryos. Under optimal conditions approximately 25,000 plants may be regenerated from a single leaf explant in seven months.