Effect of nurse cultures on the production of macro-calli and fertile plants from maize embryogenic suspension culture protoplasts.

Fertile plants have been obtained from maize (Zea mays L.) embryogenic suspension culture protoplasts. Friable, embryogenic callus initiated from an immature embryo from a cross involving the genotypes A188, B73, and Black Mexican sweetcorn was used to establish a rapidly growing embryogenic suspension culture. After nine months in culture, high yields of viable protoplasts (30×10(6)/ gram fresh weight) were obtained following a 1.5 hour enzymatic digestion. Protoplasts cultured with feeder cells divided and formed embryogenic callus, from which male and female fertile plants were regenerated. Protoplast-derived R1 plants were self-pollinated and immature R2 embryos isolated for callus initiation. Female fertile plants have also been produced from protoplasts isolated from an R2-derived suspension culture. Significant interactions between protoplast and feeder-cell lines were observed.