F. J. Novák

In vitro clonal propagation of Pisum sativum L.

A system of in vitro clonal propagation has been developed in Pisum sativum L. (cv. Bohatýr). A modified MS-medium supplemented with 20 μM 6-benzylaminopurine (BAP) and 0.1 μM α-naphthaleneacetic acid (NAA) was used to induce multiple shoot formation from shoot apices, axillary buds of the first normal leaf, axillary buds of the first and second primary scales and axillary buds of cotyledons of 4 to 6 day old pea seedlings. Meristem explants maintained a high proliferation ability in each subculture in the course of 20 months of the culture. Regenerated shoots were rooted in the same basal medium containing 5 μM NAA. Rooted plants were cultured in hydroponic pots filled with half-strength MS-medium to attain anthesis and seed maturity. The phenotypic uniformity of the regenerants was evaluated. Cytological investigation confirmed the diploid stage (2n=14) of regenerants and their progeny. Histological studies revealed that proliferating shoots originated from axillary and adventitious buds. In vitro propagation is discussed as related to pea breeding.

Karyological and Cytophotometric Study of Callus Induction in Allium sativum L.

Leaf explants of Allium sativum L. (2n = 16) were cultured in vitro on nutrient media with different hormonal composition. Karyological changes were analyzed both by chromosome counting and cytophotometry. The media containing 2,4-dichlorophenoxyacetic acid (2,4-D) alone or in combination with kinetin (KIN) and β-indoleacetic acid (IAA) were the only to induce callus formation. Callus induction was accompanied by an increase in the ploidy level. The least karyological heterogeneity was observed with callus on medium with equimolar concentrations of 2,4-D and KIN while the highest variability was recorded on medium with 2,4-D alone. Polyploid cells originated from diploid cells rather than from polyploid ones pre-existing in the explant. Restitution mitoses were most probably the main mechanism of origin of polyploid cells.

Effect of Plant Tissue Culture Media on the Frequency of Somatic Mutations in Tradescantia Stamen Hairs

Summary The mutagenicity of the plant tissue culture medium and its hormonal composition was tested in the Tradescantia stamen hair system. Although this system is highly sensitive to chemical mutagens, no alteration was observed in the frequency of somatic mutations following direct application of the culture medium to Tradescantia inflorescences regardless of its hormonal composition. It is suggested that plant tissue culture media have no direct effect on the induction of mutations in cells cultured in vitro .

Anther cultures of Nicotiana tabacum L. mutants

SummaryThe theoretically expected and experimentally observed phenotypic ratios have been compared in populations of haploids derived from chlorophyll mutants of Nicotiana tabacum L. with a known genotypic constitution. The frequencies of mutant genotypes were significantly lower than the expected values, proving the existence of selection in a system of haploid embryoids developing in the anther.The anthers from M1 plants of a diploidized Nicotiana tabacum haploid cv. Samsun, treated with various concentrations of N-nitroso-N-methylurea and n-butylmethane sulphonate, were cultivated in vitro. The number of anthers which gave rise to haploids (embryogenic anthers) was stimulated by lower concentrations of both the mutagens. The stimulation at the level of M1 sporophyte is explained by internal genetic heterogeneity induced by adequate mutagen concentration. The average number of haploids per embryogenic anther decreased in all the treatments. The frequency of haploid plants of the mutant phenotypes increased with increasing mutagen concentration.

Shoot production fromin vitro cultured flower heads ofAllium porrum L

Shoots have been produced in the explants from flower head receptacles cultured on BDS medium with BAP and/or NAA. The shoots produced could be regenerated to form the whole plants and transplanted into soil. No morphological or cytological variations were observed in mature plants. The histological analysis of adventive bud formation is presented. The importance of this method for clonal propagation ofAllium porrum plants is discussed.

Regulation of Somatic Embryogenesis and Organogenesis in Allium carinatum L.

Summary Callus cultures were derived from roots, shoots and aerial bulbils of Allium carinatum L. Regeneration was achieved either via somatic embryogenesis or organogenesis according to the type of explant. Shoot regeneration was also induced with cultures of isolated flower heads. In all instances the frequency of regeneration was high and regeneration took place for a period of more than 2 years on media with or without growth regulators.

Stability of Lanatoside C content in thein vitro propagatedDigitalis lanata clones

In vitro culture was established from shoot tips ofDigitalis lanata cotyledonous plants. The propagated plant material was rooted, transplanted into soil and grown under field conditions. Lanatoside C content was determined in a total of 20 clones and statistically evaluated by means of variance analysis of unequal-sized samples.In vitro clonal propagation ofD. lanata was found not to affect lanatoside C content. Drug level was dependent on a plant genotype.

Cytogenetic effect of plant tissue culture medium with certain growth substances onAllium sativum L. meristem root tip cells

The effect of plant tissue culture medium with different concentrations and combinations of growth regulators (kinetin, indol-3-ylacetic acid, 2,4-dichlorophenoxyacetic acid) was evaluated on mitosis ofAllium sativum meristem root tip cells. Different combinations of growth regulators at low concentrations had no effect on induction of mitotic aberrations or inhibition of mitotic activity. Inhibition of mitotic activity, a tendency to chromosome stickiness and clumping and a slight increase in the frequency of mitotic aberrations were observed at higher concentrations. It may be proposed that plant tissue culture media have no direct effect on induction of mitotic aberrations in plant tissue culturesin vitro.

Studies on the morphogenetic response of maize tissue cultures of different origin

The participation of the genotype and of organ specifity effect in the quality of morphogenetic response (callogenesis, bud and root formation) of primary maize explants has been investigated. The presence of synthetic auxins — especially 2,4-D at 1 to 5 mg 1−1 conc. - in cultivation medium was essential for both callus formation and continuous growth of tissue and suspension cultures. Anatomic structure of callus cultures is permanently heterogeneous, their growth is ensured by the action of meristems of the type found in root tips, and by repeated callogenesis from malformed roots. Adventive buds and plants could be regenerated only from cultures of embryonal origin (of one line). The presence or absence of the endosperm gene “opaque” did not influence callogenesis intensity in cultures of isolated embryos; however the morphogenetic response was clearly “line specific”.

Partial synchronization of cell division in root meristem induced by 5-aminouracil

Abstract5-aminouracil induces a partial synchronization of mitoses in barley, onion and garlic root tips. The highest degree of synchronization has been achieved in garlic where the mitotic index reached the value of about 36%, while in onion and barley the values equalled about 20%. The concentration causing the maximal synchronization in barley (400–750 ppm) was many times higher than in garlic (62.5 ppm) and onion (100 ppm). The occurrence of micronuclei was evaluated in garlic, under the conditions when synchronization was maximal. It was increased nearly tenfold as compared with the control.