Amino acids profiles were investigated in tissues, cultured cells, i.e. callus or suspension cells, and their protoplasts of three mangrove species, Avicennia alba, Bruguiera sexangula, and Sonneratia alba. Original tissues of cultured cells of three mangrove species were cotyledons and hypocotyls, leaves, and cotyledons, respectively. In protoplasts isolated from cultured cells, glutamine and alanine were the major amino acids. Different contents of glycine, proline and serine were observed among protoplasts of three mangrove species. Large differences in the major amino acids were found among cultured cells and their protoplasts while no difference was found between callus and suspension cells independent of additional salt in culture medium. Protoplasts of original tissues, young leaves and cotyledons, contained alanine and glutamine and/or asparagine. In suspension cells of B. sexangula, total contents of amino acids were low while their protoplasts showed similar value as of other samples. Protoplasts of leaf and cotyledons of A. alba and cotyledons of A. lanata, A. marina and S. alba were also investigated. The total contents of amino acids and their profiles might be related to the recalcitrance for the growth and salt tolerance or halophilic nature of cells and basal media used for the maintenance of cell cultures or protoplast cultures of the mangrove species. This is the first report on callus induction from hypocotyls of A. alba.
Liquid cultures were successfully generated from cotyledons of two Sonneratia species, S. alba and S. caseolaris in Murashige and Skoog (MS) medium containing 0.1 lmol L -1 2,4-dichlorophenoxyacetic acid (2,4-D). Adventitious roots differentiated from cotyledons of S. alba. Proliferated cells were subcultured and a large volume of suspension cells was subsequently established in 100-mL flasks. All the cytokinins tested inhibited cell proliferation. After three years of culture, the potential to differentiate was tested as indicated by greening of the cells. Greening occurred when suspension cells were transferred to solid MS medium with and without 0.1 lmol L -1 2,4-D. Greening was stimulated by low concentrations of the weak auxins indolebutyric acid (IBA) and naphthaleneacetic acid (NAA) while 2,4-D stimulated late-stage greening. Abscisic acid (ABA) inhibited greening. Gibberellic acid (GA 3 ) at 1.0 lmol L -1 stimulated callus greening and was not inhibitory even when tested at high concentrations. Cytokinins were inhibitory in combination with 0.1 lmol L -1 of either IBA or NAA. The cause of different effects of plant hormones on growth and differentiation was discussed. Small-scale liquid media and 24-well culture plates of solid media methods developed in this paper are suitable for the optimization of hormonal conditions for cell proliferation and differentiation.
Kandelia obovata Sheue, Liu & Yong sp. nov. is one of the cold tolerant mangrove plants. Some callus formation was obtained from the leaves of K. obovata in liquid medium containing 10 lM of 2,4-dichlorophenoxyacetic acid. However, recalcitrancy was found when subculturing them. Endogenous levels of gibberellins (GAs) and abscisic acid (ABA) in leaf protoplasts of K. obovata were determined using micro-scale extraction and purification steps, including thin layer chromatography and quantification by micro-bioassay or enzyme linked immunosorbent assays. Very high amounts of ABA and low activities of GAs were found in leaf protoplasts of K. obovata. Low concentrations of gibberellic acid and uniconazole-P were effective of enhancing cell enlargement in protoplast cultures. Exogenous application of ABA was inhibitory to protoplast culture. All cytokinins tested were inhibitory to both leaf and protoplast cultures. The high endogenous level of ABA is most likely the underlying cause of recalcitrancy of mangrove cultures.
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