Embryogenic Callus Formation from Protoplasts Derived from Suspension Cells of Apomictic Guineagrass (Panicum maximum Jacq.)

Abstract

Protoplasts were isolated from suspension cells of apouuictic guineagrass (Pauicum maximum Jacq.). The suspension culture used as donor Inaterial was originally initiated from immature embryoderived embryogenic callus. Prior to protoplast isolation, suspension cells were conditioned with Murashige and Skoog (MS) Iiquid medium without sucrose and growth regulators. This pretreatment lead to a dramatic increase in protoplast yield and colony formation. Cell division and colony formation from such pretreated protoplasts were found to be best in agarose-solidified modified KM8p medium. Protoplast derived colonies developed into callus on solidified MS medium supplemented with 1 mg/l 2, 4-D. After 2 months in culture, calli formed compact white nodular structures some of which developed into somatic embryos. Although some of the somatic embryos developed small leafy structures, whole plants could not be regenerated.