Halophilic and salts tolerant protoplast cultures of mangrove plants, Sonneratia alba and Avicennia alba

摘要

The effects of sea salts, NaCl, KCl, MgCl2, MgSO4, and CaCl2, on the growth of protoplast cultures of two mangrove species, Sonneratia alba and Avicennia alba, were investigated using 96-well culture plates. Plants of these two species naturally grow at the seaward side of a mangrove forest. Cotyledon protoplasts of S. alba showed halophilic nature to NaCl, KCl, and MgCl2 at low concentrations (10–50 mM) when cultured in Murashige and Skoog’s (MS) medium containing 0.6 M mannitol. CaCl2 at a concentration higher than 25 mM was inhibitory to cell growth. On the other hand, in protoplast culture of A. alba suspension cells, which were induced from cotyledon tissues, in the modified amino acid (mAA) medium containing 1.2 M sorbitol, tolerance to NaCl, MgCl2 and MgSO4 were observed at a wide range of concentrations up to 400 mM. CaCl2 was always inhibitory for cell divisions in A. alba, but stimulatory for spherical enlargement of cells. However, no difference in cell enlargement was observed among other salts. Similarity and difference in reactivity to salts between protoplasts and suspension cells from our previous studies were discussed in relation to the site of salt tolerance or halophilic adaptation within mangrove cells. For protoplast cultures, the site(s) for response of S. alba and A. alba are located in the cytoplasm and/or the cell membrane.