Báo cáo khoa học: "Compatible solutes in different organs of mangrove trees "

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in different organs of mangrove trees Compatible solutes J. Polania 2 M. 1 Popp 1 Institut für Angewandte Botanik, Universität Münster, F.R.G., and 2 Institut für Pflanzenphysiologie, Universitit Wien, Austria Introduction Materials and Methods Mangrove material was collected at the According to Brown and Simpson (1972), Dampier Archipelago (Western Australia) during a compatible solute may be "loosely defin- March/April 1984. Sample preparation and ed as one which, at high concentration, analytical procedures were those described by allows an enzyme to function effectively". Popp et al. (198:5). Culture experiments were carried out in a glass-house in Vienna with This definition was developed from work additional light and a temperature regime of on sugar-tolerant yeast and was later 28-30°C during the day and 20°C at night. adapted to halophytes, which also need Plants were grown on a substrate of volcanic osmolytes in the cytoplasm to assure the beads and supplied with appropriate concen- intracellular osmotic adjustment between trations of seawater prepared from commercial- ly available sea-salt for aquariums. 1 mM vacuole (rich in NaCI) and cytoplasm NH 1 mM NH 0.1 mM KH and , 3 NO 4 Cl, 4 4 P0 2 (poor in NaCI) (Stewart et al., 1979). 0.05 mM FeEDTA were added to the seawater. The solutions were changed every 2 wk. Whole Earlier work on mangroves has revealed plants were harvested and divided into the that these halophytic trees stored high different organs. Roots were subjected to a concentrations of either mannitol, pinitol, standardized washing-procedure. quebrachitol, proline or glycine betaine in their leaves (Popp et al., 1985). In the meantime, further work on the Rhizophor- aceae showed that the cyclitol formerly Results identified as pinitol was lD-0-methyt- muco-inositol (Richter, Thonke and Popp, manuscript in preparation). For osmotic considerations data in TableI The present study given in mo! plant water. The 3 m- ’ undertaken to was are elucidate the role of these organic solutes concentrations of Na+ and Cl- in sea- in various mangrove species by inves- water were 459 and 535 mol-m- , 3 tigating their distribution in different plant respectively, and were very often in the organs and their reaction to long- and same range in the different plant organs short-term variations in salinity. (Table I). Where; twigs could be separated
this species contained 2 additional organic into bark and wood, Na+ and CI- solutes: chiro-inositol (11-25 mol-m- and ) 3 accumulated to a higher extent in the proline (0.4-5.0 mol-m- which were ), 3 bark, while the opposite was true for the again present in all different plant parts. organic solutes. In addition to the 4 species listed in In A. long-term experiment with a Table I, we know from Rhizophora tested the influence of corniculatum, we mangle, Bruguiera exaristata, Ceriops salinity on the mannitol concentration in tagal and Laguncularia racemosa that the the leaves. Plants were kept for 1 yr at organic solutes present in the leaves also either 10 or 100% seawater, leaves of accumulated in all other plant organs. approximately the same age were harvested from 4 or 5 different plants, Compared to the other species, the respectively. The mannitol content of 10°!° pinitol content in A. annulata was low, but
imply a role different from that of the 41 ± 14.8 plants (n = 4) seawater was 3 - ol- M plant water, while in polyols. It might be postulated that proline 100% is more restricted to the cytoplasm, while it was 79 ± 7.0 plants (n = 5) seawater 3 ol-M- M plant water. the polyols also accumulate in vacuoles. The effects in the short-term experiment with A. annulata were not as pronounced. However, the up-shock (8 d in 150% Acknowledgments seawater) treatment showed a clear increase in proline concentrations in roots and stems (Table II). This work was supported by the Austrian Research Fund (project no. 5784). The kind and skillful technical assistance of G. Hermann and I. Lechner is gratefully acknowledged. Discussion and Conclusion Our results are in agreement with those References obtained for herbaceous halophytes in that one and the same organic solute was present in all organs of a given plant Briens M. & Larher F. (1982) Osmoregulation in halophytic higher plants: a comparative study of (Briens and Larher, 1982). soluble carbohydrates, polyols, betaines and Acyclic polyols, such as sorbitol and free proline. Plant Cell Environ. 5, 287-292 known to play an important mannitol, are Brown A.D. & Simpson J.R. (1972) Water rela- role in the carbohydrate metabolism of tions of sugar-tolerant yeasts: the role of intra- trees other than mangroves (Loescher, cellular polyols. J. Gen. MicrobioL 72, 589-591 1987). Our results suggest that mannitol Loescher W.H. (1987) Physiology and also functioned in the overall osmotic metabolism of sugar alcohols in higher plants. Physiol. Plant. 70, 553-557 adjustment of A. corniculatum. Further experiments are in progress to determine Popp M., Larher F. & Weigel P. (1985) Osmotic adaptation in Australian mangroves. Vegetatio if cyclic polyols (pinitol, 1 o-O-methyl- 61, 247-253 muco-inositol) behave in the same way. Stewart G.R., Larher F., Ahmad I. & Lee J.A. Proline accumulation in A. annulata was (1979) Nitrogen imetabolism and salt tolerance similar to that observed for herbaceous in higher plant halophytes. Symp. Ecological halophytes (Stewart et aL, 1979). The Processes in Coastal Environments (Jefferies reaction to changes in salinity and the R.L. & Davy A.J., eds.), Blackwell Sci. Publ., rather low concentration of this solute London, pp. 211-:227