Somaclonal variation from Sorghum bicolor (L.) Moench cell culture

Plant Cell, Tissue and Organ Culture (PCTOC) - Sorghum bicolor (L.) Moench, plants were regenerated from 4 to 5 month old callus cultures originally derived from seedling explants. Somaclonal...     

Phaseollin production in cell suspensions and whole plants of Phaseolus vulgaris

Production of phaseollin was measured in cell suspension cultures and whole plants of Phaseolus vulgaris. In suspension cultures phaseollin appeared when there was no further increase in cell mass. Cells transferred to a medium without auxins yielded three times higher phaseollin concentrations than cells grown in their presence. Addition of autoclaved fungal mycelia or polysaccharides as elicitors resulted in an increased phaseollin concentration in the cell suspension.In whole plants phaseollin could be detected only after the plants were challenged by a fungus which caused lesions (browning) of the upper root neck region, Rhizoctonia solani. Treatment of non-infected plants with autoclaved fungal mycelia or other elicitors did not induce phaseollin production. However, when they were added before or together with the pathogenic fungus, the elicitors further increased phaseollin concentration in the root neck regions of the plants. This indicated that the pathogenic fungus was important for the penetration of the elicitors to inner plant tissues where phaseollin (and probably other phytoalexins) is produced.     

Vitrification of carnation in vitro: Changes in cell wall mechanical properties,cellulose and lignin content

Vitrification of internodes of carnation was brought about by culturing in liquid medium. Cell wall extensibility of these internodes was kinetically followed in comparison to that of normal plants using the constant stress method. Liquid culture induced increased immediate and total deformation capacities of the walls from the second day. Measurements indicated that these deformation capacities involved plastic properties rather than elastic ones. These changes were paralleled by decreased relative levels of cellulose and lignin.     

In vitro propagation of Alstroemeria ‘Alsaan’

Plantlets were regenerated from Alstroemeria Alsaan rhizome tips cultured in vitro on solid and liquid media based on Murashige and Skoog salt formulation. The quality of the cultures was superior when intact rather than longitudinally sliced rhizome tips were used as explants and when a temperature of 8°C rather than 22°C was used at the initiation stage. More roots were produced on rhizome tips containing a rhizome apical meristem than on rhizome sections lacking such a meristem. Most (90%) of the rooted plantlets were successfully acclimatized and developed into true-to-type flowering plants.     

In vitro regeneration of apomictic bluestem grasses

Explants from immature inflorescences of four genotypes of Old World bluestem grasses, (Bothriochloa spp.), produced callus tissue on Linsmaier and Skoog (RM) and 1/2 Murashige and Skoog (1/2 MS) media containing high levels of growth regulators. Callus masses were composed of two distinct tissue types, one a compact, white, embryogenic portion (E calli), the other soft, translucent, gelatinous and nonembryogenic (NE calli). When transferred to medium with a reduced level of 2,4-D, and/or supplemented with zeatin, E callus underwent further organization culminating in shoot production. Light and scanning electron microscopy confirmed the embryogenic pathway of differentiation. Genotype significantly affected callus induction frequency and the number of plants regenerated. The RM medium induced more explants to initiate callus compared to the 1/2 MS medium. Age of the inflorescence explant, as indicated by size, was critical for callus induction. Inflorescences with racemes 8 mm in length were superior to older ones. Five-hundred-twenty-two plantlets were regenerated and grown to maturity.     

In vitro organogenesis and plant regeneration from leaves of Solanum candidum Lindl,S. quitoense Lam. (naranjilla) and S. sessiliflorum Dunal

Adventitious shoots and roots were regenerated from leaf segments of 3 Solanum species: S. candidum Lindl., S. quitoense Lam. and S. sessiliflorum Dunal. Leaf explants differentiated shoots on modified MS medium supplemented with 23–163 M kinetin and 0–5.7 µM indoleacetic acid (IAA). Excised shoots were induced to form roots by transfer to media with benzyladenine (BA) and naphthaleneacetic acid (NAA) at 0.09 and 0.11 µM respectively for S. quitoense and 0.01 µM NAA for S. candidum and S. sessiliflorum. Adventitious roots were produced directly from leaf explants with 0–140 µM kinetin and 0–5.7 µM IAA in combination. Rooted plants were successfully established in the greenhouse.     

Initiation and maintenance of long term somatic embryogenesis from anthers and ovaries of Vitis longii ‘Microsperma’

Anthers and ovaries of Vitis longii Microsperma produced embryogenic callus when cultured on solidified Murashige and Skoog medium with 5M 2,4-dichlorophenoxyacetic acid (2,4-D) and 1M benzyladenine (BA). The initial callus was short-lived. However, long-term embryogenesis from callus was maintained through serial transfers by careful selection of clustered embryos with subtending callus. Alternatively, long term culture maintenance was through secondary embryogenesis which occurred directly from previously formed embryos on medium lacking growth regulators. Somatic embryos were white, exhibited frequent pluricotyly and tended to be larger than zygotic embryos. Histology of embryogenic callus demonstrated the presence of lipid-like substances and abundant starch. Somatic embryos were attached to callus by narrow to wide suspensor-like structures and possessed typical epidermal, cortical, and vascular tissue. Embryo cells contained abundant lipid-like accumulations but no starch. Embryos germinated when placed on medium containing 1M BA and produced plants of normal appearance.     

In vitro proliferation of saffron (Crocus sativus L.) stigma

Excised young intact stigmas plus ovaries of Crocus sativus L. were cultured on Linsmaier-Skoog media supplemented with either a cytokinin or an auxin alone or in combinations. Benzyladenine and kinetin at concentrations of 0.1, 1, and 5 mgl^-1 supported growth, and crocin was biosynthesized in the stigmas in vitro. Auxins had little effect. Young excised single stigmas or half ovaries were also cultured so as to form stigma-like structures in order to explore a possible new approach to industrial production of the spice, saffron. On Linsmaier-Skoog and Nitsch media supplemented with kinetin at concentration of 1 or 5 mgl^-1 and alpha-naphthalene acetic acid or indole-butyric acid at concentration of 0.1 or 10 mgl^-1 in combinations, stigma-like structures appeared directly and indirectly (through meristematic tissue), grew and matured. The maximum number of structures were 75 per half ovary. Three kinds of yellow pigments including crocin were tentatively identified by TLC in the stigma-like structures as was the case for the in vivo grown natural stigma, although the contents were lower.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxy-acetic acid - IAA indole-acetic acid - IBA indole-butyric acid - NAA alpha-naphthalene-acetic acid - TLC thin layer chromatography     

The Chlamydomonas cell cycle is regulated by a light/dark-responsive cell-cycle switch

Cultures of the unicellular green alga Chlamydomonas reinhardii can be synchronized by light/dark cycling not only under photoautotrophic but also under mixotrophic growth conditions. We observed that cultures synchronized in the presence of acetate continue to divide synchronously for one cell-cycle period when transferred to heterotrophic growth conditions. This finding enabled us to investigate the differential effects of light on cell growth and cell division. When cells were exposed to continuous light at the beginning of the growth period they entered the division phase earlier than dark-grown cells as a consequence of an increased growth rate. Illumination at the end of the growth period, however, caused a considerable delay in cell division and an extended growth period. The light-induced delay in cell division was also observed in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), an inhibitor of photosystem II. This finding demonstrates that cell division is directly influenced by a light/dard-responsive cell-cycle switch rather than by light/dark-dependent changes in energy metabolism. The importance of this light/dark control to the regulation of the Chlamydomonas cell cycle was investigated in comparison with other control mechanisms (size control, time control). We found that the light/dard-responsive cell-cycle switch regulates the transition from G1-to S-phase. This control mechanism is effective in cells which have attained the commitment to at least one round of DNA replication and division but have not attained the maximal cell mass which initiates cell division in the light.Abbreviations dCTP deoxycytidine 5-triphosphate - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea