Aluminium-tolerant regenrants from potato cell cultures

Summary Cell cultures were developed from dihaploid clones ofSolanum tuberosum L. Selection in cell suspensions as well as plating of cells on selective medium supplemented with 5 mmol Al produced tolerant cell lines. The constancy of Al-tolerance of cell lines was confirmed by culturing the calli for 3 months in Al-free medium and then transferring them back to selective medium. 4 tolerant regenerant clones were obtained which maintained Al-tolerance also after subculture in control medium. Two of the 4 clones that constantly maintained Al-tolerance, originated from cell lines subcultured for 5 months under stress conditions. However, the regeneration rate of these cell lines was low compared with that of lines obtained after a shorter selection period.     

Influence of Sucrose and Melibiose on Barley Anther Cultures in Starch Media

Anthers from the barley varieties ‘Arra’, ‘Dissa’ and ‘Ingrid’ were cultured in barley starch gelatinized nutrient media. The importance of osmosis in barley starch medium was studied by using sucrose or an inert carbohydrate, melibiose, as an osmoticum. It was found that in the barley starch medium sucrose was not necessary but energy and carbon could be obtained by tissue enzymatically from the starch. Together with the starch medium melibiose had revolutionary effects OB barley anther cultures. This system not only produced extremely high numbers of embryoids and green plantlets but also drastically reduced the number of albinos.     

Methods for Selection of Low-Temperature Tolerant Mutants of Chrysanthemum morifolium Ramat. Using Irradiated Cell Suspension Cultures III. Comparison of Mutants Selected with or without Preselection in vitro at Low-Temperature

One hundred variants of Chrysanthemum morifolium cv. ‘Parliament’, selected on a single plant basis for early flowering at low temperature, were tested on a clonal basis. These variants originated from irradiated or non-irradiated microcalli subjected to a one-step greenhouse selection procedure, or, a two-step selection procedure (preselection in vitro at 6°C followed by selection in the greenhouse). Clones originating from irradiated calli flowered significantly earlier than the controls. Most of the low-temperature tolerant (LTT) mutants were found among plants obtained by the one-step selection procedure. Variants originating from slowly regenerating calli yielded more LTT mutants as compared to those of fast(er) regenerating calli. We therefore conclude that, irradiation and subsequent selection of plants from slowly regenerating calli considerably increases the efficiency of selecting LTT mutants. The expected advantage of a preselection in vitro at low-temperature could not be confirmed.     

Chromosome Irregularities in Wheat and Triticale Plants Regenerated from Leaf Base Callus

Basal leaf sections of Triticum aestivum L., cv. ‘Chinese Spring’, and XTriticosecale Wittmack cv.‘Welsh’were cultured on Kao's medium with 2 mg/l of 2,4-D. Callus was induced on the leaf sections at frequencies of 64 and 63 %, respectively, and plant-lets regenerated at 18 and 31 %, respectively. Compared to the controls, the regenerated plants showed higher frequencies of univalent chromosomes at meiosis and low frequencies of trivalents, and quadrivalents; indicating that the callus phase had induced low frequencies of chromosome irregularity.     

Methods for the Selection of Low-Temperature Tolerant Mutants of Chrysanthemum morifolium Ramat. by Using Irradiated Cell Suspension Cultures

In order to improve mutant selection procedures, 5000 plantlets were regenerated in three different harvests (flush A, B and C) from X-irradiated (15 and 20 Gy) and non-irradiated cell suspensions of Chrysanthemum morifolium cv. ‘Parliament’. After screening under suboptimal energy condition (12°C greenhouse temperature, winter low-light), a total of 95 early flowering plants were selected. These plants flowered at least as early as a low-temperature tolerant (LTT) mutant E₂, used as a reference. The percentage of early flowering variants was highest among plants obtained from calli, X-irradiated with 15 Gy and regenerating relatively late (flush B). It appeared that the applied selection method (e.q. harvest) had a large impact on the number of early plants obtained.