Plant regeneration from embryogenic cell suspension-derived protoplasts of rubber

Embryogenic cell suspensions of rubber derived from immature inflorescences and inner integuments of immature fruits released 3.1 +/- 0.2 x 10(7) protoplasts g(-1) f. wt. (mean +/- s.e.m, n = 10) and 3.2 +/- 0.2 x 10(7) protoplasts g(-)1 f. wt., with mean viabilities of 83 +/- 2% and 77 +/- 8%, respectively. Sustained mitotic division was observed only when protoplasts were cultured in KPR liquid medium on nitrocellulose membranes overlying the same semi-solid medium containing Lolium multiflorum nurse cells. Protoplast-derived cell colonies were produced within 2 months of culture. Protoplast-derived cell colonies proliferated, upon subculture to MS-based regeneration medium, with 40% of the protoplast-derived calli developing somatic embryos. The latter germinated into plants on the same medium after 3 months of culture.