Somatic Embryogenesis and Plant Regeneration from Freely-suspended Cells and Cell Groups of Panicum maximum Jacq*

Abstract

Embryogenic calluses derived from cultured immature embryos and young inflorescences of Panicum maximum Jacq. were placed in Murashige and Skoog's liquid medium supplemented with 1 mg 1⁻¹ 2, 4- dichlorophenoxyacetic acid (2, 4-D) and 2.5 per cent coconut water, to initiate suspension cultures. Suspensions consisted of two types of cells: small, richly-cytoplasmic and often starch-containing embryogenic cells, and large, vacuolated non-embryogenic cells. A presumed sequence of developmental stages from single embryogenic cells to globular and heart-shaped stages of embyrogenesis was observed in the suspension cultures. Plantlets were produced from the embryoids when the suspensions were plated in an agar medium without any hormone or with only 0.2 mg 1⁻¹2, 4-D or naphthalene acetic acid. Embryogenic suspension cultures derived from immature embryos as well as from inflorescence segments gave rise to plants which showed the normal somatic chromosome number of 2n = 4x = 32.