Search Results
A method is described for separating large and small pollen effectively from a heterogeneous mixture. This method potentially is applicable to separation of pollen grains of different ploidy levels, since “unreduced” 2n pollen is larger than normal pollen (n); it might then be used to increase the efficiency of a breeding program employing sexual polyploidization and to diminish crossing inefficiencies in interploid crosses.
Abstract
Methods were developed for efficient shoot regeneration from leaf and runner tissues of the strawberry (Fragaria × ananassa) cultivars Allstar and Honeoye. Optimal regeneration conditions differed for ‘Allstar’, depending on whether leaf tissue was derived from plantlets grown in vitro or from plants grown in the greenhouse. ‘Allstar’ leaf tissues derived from in vitro cultures regenerated shoots most efficiently in a Linsmaier–Skoog (LS) medium containing 2.5 mg BA and 0.5 mg IBA/liter. ‘Allstar’ leaf tissues derived from greenhouse plants regenerated shoots best in LS medium containing 3.0 mg BA and 0.1 mg IBA/liter. Addition of casein hydrolysate (CH) at either 400 or 600 mg·liter−1 stimulated shoot production. A supplement of KNO3 at 2000 mg·liter−1 also enhanced regeneration efficiency of greenhouse-grown leaf tissues. ‘Honeoye’ had lower regeneration potential in most treatments than ‘Allstar’ and only produced shoots in a LS medium containing 5.0 mg BA, 0.5 mg IBA, and 400 mg CH/liter. Shoots from runner tissues of both cultivars were best obtained using LS medium containing 10.0 mg BA, 2.0 IAA, and 500 mg CH/liter. Shoot production from runners was dependent on the diameter of the runner, with diameters of <2.0 mm having poor regeneration potential. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA); 1H-indoIe-3-butyric acid (IBA); and 1H-indole-3-acetic acid (IAA).
Abstract
‘Royalty’ is a new purple raspberry cultivar with the high fruit quality of the red raspberry (Rubus idaeus L.) and the vigor and large fruit size associated with the purple raspberry (R. idaeus × R. occidentalis L). The cultivar is hardy and has wide adaptation and good yield potential. It has immunity to Amphorophora agathonica Hottes, the aphid vector of the raspberry mosaic virus complex, and resistance to Aphis rubicola Oestland, the aphid vector of raspberry leaf curl. It also shows resistance to Byturus rubi Barber, the raspberry fruit worm.
The biolistics process uses high velocity microprojectiles to carry foreign DNA into cells. Though biolistics has already proven to be useful fo r a wide range of species, improvements are still needed, and many of the factors which affect transformation efficiency have not been defined. In our experiments, cell suspensions of Nicotiana tabacum (NT1 line) were used as a model to identify these factors. The most critical factors for high efficiency transformation were: cell age, microprojectile type & size, DNA construct, osmoticum in the bombardment medium, use of a new helium-driven biolistic device, and the handling and growth environment of the cells after bombardment. By optimizing these factors, an average of 7,000 transiently expressing GUS cells and 800 kanamycin resistant colonies were obtained per bombarded plate. The high efficiency and rapid results (2 days transient/4 weeks stable) of the NT1 model system make it useful for cell biology studies and for testing DNA constructs.
Physical and biological parameters affecting the efficiency of biolistic transformation of peach were optimized using ß-glucuronidase (GUS) as a reporter gene, such that efficiency of transient GUS expression in peach embryo-derived callus was increased markedly. Transient expression was also obtained in embryonic axes, immature embryos, cotyledons, shoot tips, and leaves of peach. Stable expression of a fusion gene combining neomycin phosphotransferase (NPTII) and ß-glucuronidase activities has been achieved in peach embryo calli. Sixty-five kanamycin-resistant callus lines were obtained from 114 pieces of bombarded calli after 4 months of selection. Nineteen of the 65 putative transformant lines produced shoot-like structures. Seven lines were examined to confirm stable transformation using the colorimetric GUS assay and PCR analysis. All seven lines showed GUS activity. PCR analysis confirmed that, in most of the putative transformants, the chimeric GUS/NPTII gene had been incorporated into the peach genome. The transgenic callus lines were very weakly morphogenic, presumably because the callus was 5 years old and no transgenic shoots developed from this callus. Results of this research demonstrate the feasibility of obtaining stable transgenic peach tissue by biolistic transformation.
Abstract
‘Honeoye’ and ‘Canoga’ are 2 new cultivars of strawberry (Fragaria X ananassa Duch.) released by the New York State Agricultural Experiment Station in 1979 (1).