Streptomycin resistant and sensitive somatic hybrids of Nicotiana tabacum + Nicotiana knightiana: correlation of resistance to N. tabacum plastids

Improved efficiency of plant regeneration from protoplasts of eggplant Solanum melongena L

Eggplant (Solanum melongena L.) mesophyll protoplasts were obtained from in vitro growing plants of line 410 and cv. 'Classic'. Relatively high (15%) plating efficiency was achieved using petri dishes with alternate quadrants containing reservoir medium (R medium + 1% activated charcoal) and culture medium. Shoot regeneration occurred within 6 weeks following initiation of protoplast culture.

High frequency of fusion induced in freely suspended protoplast mixtures by polyethylene glycol and dimethylsulfoxide at high pH

Fusion of freely suspended protoplast mixtures (hypocotyl protoplasts of Brassica napus mixed with mesophyll protoplasts of either B. campestris or Nicotiana plumbaginifolia) was induced by a solution containing 10% polyethylene glycol, 10% dimethyl-sulfoxide and 0.1M glycine-NaOH buffer (pH 10.0). The fusion products represented 15 to 17 percent of the surviving cells. More than 50% of the fusion products divided within two days after fusion, indicating that the fusion procedure did not significantly affect the viability of fused cells. The fusion products were not bound to the surface of the fusion vessel, so they could be isolated with a micropipette immediately after fusion.

Cloning of Petunia hybrida chloroplast DNA sequences capable of autonomous replication in yeast

Sequences from Petunia hybrida chloroplast DNA which have the property to promote autonomous replication in Saccharomyces cerevisiae were cloned in vector YIp5. Seven cloned chloroplast DNA fragments are localized at one of two different sites on the chloroplast genome. One site, arsA was mapped on a 1.8 Kb fragment at position 27.0-28.8 Kb on the P. hybrida chloroplast genome. The plasmids containing this arsA are stable both in yeast and E. coli. The other site, arsB, was shown to be very unstable and is located either in the small single copy region close to the inverted repeat or just in the inverted repeat. The functioning of these sequences as a possible origin of replication in vivo is discussed.

Improved culture ability of potato protoplasts by use of activated charcoal

Protoplasts were obtained from in vitro grown plants of Solanum tuberosum L. The protoplasts were cultured in X-plate petri dishes with the culture medium joined to a reservoirmedium. When activated charcoal was added to the reservoirmedium the culture ability of the protoplasts was significantly increased. The effect of activated charcoal was mainly due to a less pronounced browning of the developing protoplasts and this technique might be of help in protoplast cultures where browning is a problem.

Cybrids containing mixed and sorted-out chloroplasts following interspecific somatic fusions in Nicotiana

Streptomycin resistance was transferred by "donor-recipient" protoplast fusion from Nicotiana tabacum (SR-1) protoplasts into Nicotiana tabacum (cytoplasmic male sterile - Line 92) protoplasts in one case and into Nicotiana sylvestris protoplasts in another. It is demonstrated that streptomycin resistance (SR-1) is a chloroplast marker which segregates independently from a mitochondrial marker.In the fusion experiment where Nicotiana tabacum (Line 92) was the recipient, microcalli were plated in the presence of streptomycin. In this case, chloroplast sorting out occurred at a stage preceeding plant regeneration, producing stable streptomycin resistant cybrids. In the fusion whre Nicotiana sylvestris was the recipient, no direct selection for streptomycin resistance was performed. In this case chloroplast sorting out was incomplete, thus producing cybrid plants with a mixed chloroplast population. In some plants, sorting out of streptomycin resistant and sensitive chloroplasts was still apparent in the second generation progeny.

Intertribal hybrid cell lines of Atropa belladonna (X) Nicotiana chinensis obtained by cloning individual protoplast fusion products

After fusion of isolated mesophyll protoplasts of belladonna (Atropa belladonna) with callus protoplasts of Chinese tobacco (Nicotiana chinensis) followed by mechanical isolation and cloning of individual heteroplasmic fusion products, 13 cell clones were obtained. The hybrid nature of most of the clones has been confirmed by biochemical (studies of amylase isozymes), cytogenetic (size and morphology of chromosomes) and physiological (peculiarities of cell-growth in vitro) analyses. Study of chromosomes and isozyme patterns in the hybrid cell lines revealed the presence of both parental genomes, without an indication of chromosome elimination, six months after hybridization. In 4 cell lines shootlike structures and plantlets have been produced by means of transfer to organogenesis-inducing media. The data obtained are interpreted as new evidence for the possibility of using non-sexual hybridization for the production of intergeneric, intertribal plant hybrids which cannot be obtained by sexual crossing. From these results the potential of Atropa (X) Nicotiana hybrids as a model system for genetic studies of distantly related plant species is discussed.

Chloroplast transfer in Nicotiana based on metabolic complementation between irradiated and iodoacetate treated protoplasts

Protoplasts of a light sensitive plastome mutant of Nicotiana tabacum (2 n=48) were irradiated and fused with iodoacetate-treated Nicotiana plumbaginifolia (2 n=20) protoplasts. Treated parental protoplasts were unable to divide. Metabolic complementation, however, helped the recovery of interspecific fusion products which survived and formed calli. Altogether 40 clones were investigated. N. plumbaginifolia plants were obtained in 15 clones (38%), somatic hybrids in 23 clones, and both types of regenerates were found in 2 clones. Irradiation therefore significantly increased the frequency of segregant formation with the non-irradiated N. plumbaginifolia nuclei (the frequency was 1.4% in the absence of irradiation). Regenerated plants in most cases (31 out of 34) contained chloroplasts from the irradiated parent. In 6 clones plants were obtained with both types of chloroplast. Thus, irradiated N. tabacum chloroplasts had an improved chance of dominating the heterokaryonderived cells, many of which contained N. plumbaginifolia nucleus. The system described should be generally applicable for the transfer of chloroplasts without the use of selectable genetic markers.

Streptomycin resistance is inherited as a recessive Mendelian trait in a Nicotiana sylvestris line

The SR180 cell line has been isolated in a callus culture derived from a haploid Nicotiana sylvestris (n = X = 12) plant by its ability to proliferate on a selective medium containing 2,000 μg/ml streptomycin sulphate. From the cell line diploid plants have been regenerated. The SR180 selfs are resistant to streptomycin. Streptomycin sensitivity in F1, and a 3∶1 (sensitive to resistant) segregation in F2 indicate that resistance in the SR180 mutant is the result of a recessive Mendelian mutation.