J.B. Power

The isolation, culture and regeneration of leaf protoplasts in the genus Petunia

Abstract Conditions are described for the isolation and culture of leaf mesophyll protoplasts of several Petunia species. Callus produced from these protoplasts underwent organogenesis with the eventual production of plants. Differences in growth behaviour are discussed with respect to taxonomic relationship in the genus Petunia. Furthermore growth requirements of the sexual hybrid between P. hybrida and P. parodii are compared to those of the parents.

Selection procedures for the production of inter-species somatic hybrids of Petunia hybrida and Petunia parodii II. Albino complementation selection

Abstract An albino complementation selection procedure has been developed for the selection of somatic hybrids of Petunia hybrida and Petunia parodii . The method involves fusing albino suspension culture protoplasts with leaf mesophyll protoplasts of the other species, and selecting green colonies formed as a result of complementation and selective growth. This selection procedure should be readily applicable to a wide range of inter-species fusions, including those of sexually incompatible species.

Somatic hybridization in Petunia: A male sterile cytoplasmic hybrid

Abstract Fusion was induced between leaf mesophyll protoplasts of a cytoplasmic male sterile (cms) and a fertile petunia line. The selection system was designed to allow only the growth of protoplasts possessing the genome of the fertile line. The majority of plants which were regenerated from protoplasts were phenotypically similar to the fertile line. Some of these plants were cytoplasmic hybrids (cybrids), combining the (S) cytoplasm from the male sterile line with the genome of the fertile line.

Genetical studies with petunia leaf protoplasts I. Genetic variation to specific growth hormones and possible genetic control on stages of protoplast development in culture

Abstract Using leaf protoplasts of several highly inbred lines of petunia, it was possible to identify genetic variations with respect to their potential for growth on media containing specific hormone combinations. Following the testing of individual plants of two species with different hormone requirements, together with their F 1 and backcrosses to the two parental lines, it was concluded that only a few genes may control such differences. The data also suggest that different stages of protoplast development may be controlled by different genes. The implications of this are discussed in relation to the development of selection procedures for the recovery of somatic hybrids following protoplast fusion.

Some consequences of the fusion and selective culture of petunia and parthenocissus protoplasts

Abstract Differences in the growth requirements of isolated protoplasts and regenerated cells of two species, Petunia hybrida and Parthenocissus tricuspidata crown gall, were sufficiently consistent to develop a selection procedure, aimed at preferentially recovering potential somatic hybrid material, following protoplast fusion and subsequent culture. Callus, obtained as a result of the selective culture of sodium nitrate-treated protoplasts, was shown to possess the chromosomes of Parthenocissus only, yet exhibited isoperoxidases,of both Parthenocissus and petunia. The callus retained isoperoxidases, associated with both species, for approximately one year, but thereafter the petunia-specific isoperoxidases were progressively lost. The implications of this are discussed with respect to the potential of the somatic hybridisation of distantly related plant species.

The effect of temperature on the division of leaf protoplasts of Lycopersicon esculentum and Lycopersicon perivianum

Abstract Protoplasts were isolated from mesophyll tissue of Lycopersicon esculentum and Lycopersicon peruvianum . Protoplasts of both species underwent continued division with the formation of callus. A critical influence of temperature was observed for the initiation and maintenance of protoplast division.

Polyethylene glycol-induced uptake of micro-organisms into higher plant protoplasts: An ultrastructural study

Abstract Protoplasts isolated from suspension-cultured cells of Parthenocissus tricuspidata take up yeast cells, yeast protoplasts, and blue-green algal cells when treated with polyethylene glycol (PEG). Electron microscopy has shown the micro-organisms to become localised in membrane-bounded vesicles in the cytoplasm of the higher plant protoplasts.

Plant production from leaf protoplasts of Petunia parodii

Abstract Protoplasts were isolated enzymatically from leaves of an inbred line of Petunia parodii. The leaf mesophyll protoplasts, plated in a nutrient medium solidified with agar, underwent cell wall regeneration, followed by repeated cell division to produce callus. Callus masses differentiated shoots which subsequently developed into normal fertile plants.

Selection procedures for the production of inter-species somatic hybrids of Petunia hybrida and Petunia parodii I. Nutrient media and drug sensitivity complementation selection

Abstract Three methods of selection are described for the production of somatic hybrids of Petunia hybrida and Petunia parodii . Using cultured leaf protoplasts of the F 1 sexual hybrid, and the two parents, it was possible to develop media in which only protoplasts of the sexual hybrid would grow. Following fusion treatments, protoplasts were plated in such media in order to assess the frequency of somatic hybrid plant production and selection efficiency.

Polyethylene glycol-induced transplantation of chloroplasts into protoplasts: An ultrastructural assessment

Abstract Mixtures of protoplasts from suspension-cultured cells of Parthenocissus tricuspidata and chloroplasts from Petunia hybrida were treated with polyethylene glycol (PEG). The envelope of intact chloroplasts readily fused with the protoplasts plasmalemma to establish continuity between the chloroplast stroma and the protoplast cytoplasm. Broken chloroplasts became localised in membrane-bounded vesicles in the cytoplasm of the higher plant protoplasts.