Taxonomic and ecological aspects of the distribution of glycinebetaine and related compounds in plants

Abstract

The concentrations of the major inorganic ions and glycinebetaine, choline and proline and the osmotic pressure of extract sap have been determined in eight salt marsh species and four sand dune species from local habitats. These results together with those previously reported on hydroponically grown plants and data assembled from the literature show that glycinebetaine accumulation is a feature of members of the Chenopodiaceae, Amaranthaceae, many Gramineae and some members of the Solanaceae and Compositae, particularly when exposed to conditions of low soil water potential. It is suggested that in these families betaine is employed as a non-toxic cytoplasmic osmoticum when decreased osmotic potentials are required. In some other plant species proline may fulfil a similar function. Another quaternary ammonium compound may be accumulated in the Plumbaginaceae in addition to proline. Some evidence suggests that the differences in the organic osmoticum used may relate to the different inorganic ion contents of the plants. The accumulation of nitrogen dipoles as cytoplasmic osmotica may make heavy demands on the nitrogen economy of the plants and this problem is discussed briefly.

Rapid Osmotic Adjustment by a Succulent Halophyte to Saline Shock

“…However, high concentrations of Mg2' have been reported for a variety of halophytes and often exceed the concentration of K+ (e.g. species of Salicornia, Suaeda, Limonium, Armeria) (11,27). Albert and Popp (2) maintain that concentrations of Mg2+ exceeding that of K+ are found only in plants from saline habitats.…”

“…Compartmentation of extraneous ions in the vacuole would necessitate an equal amount of compatible solutes in the cytoplasm to balance the water potential. Small organic molecules that could act alone as osmotica in the cytoplasm without disruption of metabolic reactions have been reported (4,10,21,24,26,27 possible mechanism for cytoplasmic osmotic adjustment is a general increase in osmotica as suggested by Greenway and Sims (15) or an increase in two or more organic solutes together (10, 24).The experimental design used by most investigators of salt tolerance mechanisms in terrestrial halophytes has been to grow them in ranges of salinity, followed by analyses of potential osmotica. There is little experimental evidence for the changes that occur in the leaves of halophytes when subject to salinity shock, i.e.…”

“…Compartmentation of extraneous ions in the vacuole would necessitate an equal amount of compatible solutes in the cytoplasm to balance the water potential. Small organic molecules that could act alone as osmotica in the cytoplasm without disruption of metabolic reactions have been reported (4,10,21,24,26,27). Another 'Supported by National Science Foundation Grant GB-3485 and the University of Utah Research Fund.…”

Proline: A Novel Cryoprotectant for the Freeze Preservation of Cultured Cells of Zea mays L

“…"Cold hardening" by pregrowth at low temperatures (14,16), pregrowth in medium of enhanced osmosity to reduce cell volume and increase the cytoplasm to vacuole ratio (23,24), and desiccation (21, see also 24), have led to marked improvements in recovery of some frozen plant tissue cultures. All of these pretreatments may induce intracellular accumulation of proline by analogy with established effects (2,12,17,18). Alteration of the level of saturation of membrane fatty acids during cold hardening may be the critical factor leading to cold tolerance in some cases but not all evidence points to this (19).…”

“…However, cryoprotectant toxicity and rehydration/deplasmolysis injury upon thawing and cryoprotectant removal contribute at present to viability losses which may delay or often preclude recovery (21 (20), prompts the search for other compounds. Proline, which has been implicated in protection against salt stress in halophytes (17,18) and cold and desiccation stress in a wide range of plants (2,12), is an ideal candidate for natural cryoprotection since it has a very high solubility, is neutral, exerts a high osmotic pressure, and is nontoxic at high concentrations (3, 17). Exogenously applied proline can confer stress resistance to plant tissues (17, see also 6), for example, tolerance of cooling to -7 C has been reported (8).…”