Mesembryanthemum crystallinum

Mesembryanthemum crystallinum leaves (S) Barley leaves and roots... 

Hofner, R., Vazquez-Morena, L., Winter, K., Bohnert, H.J. Schmitt, J.M. (1987). Induction of Crassulacean acid metabolism in Mesembryanthemum crystallinum by high salinity mass increase and de novo synthesis of PEP-carboxylase. Plant Physiology, 83, 915-19. 

Hokum, J.A.M. Winter, K. (1982). Activity of enzymes of carbon metabolism during the induction of Crassulacean acid metabolism in Mesembryanthemum crystallinum L. Planta, 155, 8-16. 

Ostrem, J.A., Olson, S.W., Schmitt, J.M. Bohnert, H.J. (1987). Salt stress increases the level of translatable mRNA for phosphoenolpyruvate carboxylase in Mesembryanthemum crystallinum. Plant Physiology, 84,1270-5. 

Struve, I., Weber, A., Liittge, U., Ball, E. Smith, J.A.C. (1985). Increased vacuolar ATPase activity correlated with CAM induction in Mesembryanthemum crystallinum and Kalanchoe blossfeldiana cv. Tom Thumb. Journal of Plant Physiology, 117, 451-68. 

An intriguing stress-induced alteration in gene expression occurs in a succulent plant, Mesembryanthemum crystallinum, which switches its primary photosynthetic CO2 fixation pathway from C3 type to CAM (Crassulacean acid metabolism) type upon salt or drought stress (Winter, 1974 Chapter 8). Ostrem et al. (1987) have shown that the pathway switching involves an increase in the level of mRNA encoding phosphoenol-pyruvate carboxylase, a key enzyme in CAM photosynthesis. 

Winter, K. (1974). EnfiuB von Wasserstreb auf die Aktivitat der Phosphoenol-pyruvat-Carboxylase bei Mesembryanthemum crystallinum (L.). Planta, 121 147-53. 

Vogt, T. et al., Light-induced betacyanin and flavonol accumulation in bladder cells of Mesembryanthemum crystallinum, Phytochemistry, 52, 583, 1999. 

Ibdah, M. et al.. Spectral dependence of flavonol and betacyanin accnmnlation in Mesembryanthemum crystallinum nnder enhanced nltraviolet radiation. Plant Cell Environ., 25, 1145, 2002. 

A cDNA for an OMT (PFOMT) with wide substrate acceptance that includes flavonols and HCA derivatives has been identified from Mesembryanthemum crystallinum (ice plant). 

DeRocher, E.J., Michalowski, C.B. Bohnert, H.J. (1991). cDNA sequences for transcripts of the ribulose-l,5-bisphosphate carbox-ylase/oxygenase small subunit gene family of Mesembryanthemum crystallinum. Plant Physiology 95, 976-8. 

Winter, K. von Willert, D.J. (1972). NaCI-induzierter Crassulaceen Saurestoffwechsel bei Mesembryanthemum crystallinum. Zeitschrift fur Pflanzenphysiologie 67, 166-70. 

Conyza canadensis (L.) Cronq. or Erigeron canadensis L. Mesembryanthemum crystallinum L. 

Keiller, D. R., Paul, M. J., and Cockbum, W. 1987. Regulation of reserve carbohydrate metabolism in Mesembryanthemum crystallinum exhibiting C3 and CAM photosynthesis. New PhytoL 197,1-13. 

Mesembryanthemum RIP1 (33kDa [reading frame]) Mesembryanthemum crystallinum (Aizoaceae) [plant] PAG (rabbit M. crystallinum rRNA)... 

Rammesmayer, G., Pichorner, H., Adams, P., Jensen, R., and Bohnert, H.J., 1995, Characterization of IMT1, myo-inositol O-methyltransferase, from Mesembryanthemum crystallinum. Arch. Biochem. Biophys. 322 183-188. 

Clones of cDNAs have been isolated from pea (7), spinach (8) and Mesembryanthemum crystallinum (9). The deduced amino acid sequences are approximately 90% identical, a high level of similarity. A small gene family, probably two or three copies (7,8,9), encodes the FNR precursor. This 43 kDa precursor, of 360 amino acids in peas, is processed after import by the chloroplast to its mature size of 35kDa by removal of a 52 amino acid transit peptide (7). 

ENVIRONMENTAL AND HORMONAL DEPENDENCE OF INDUCTION OF CRASSULACEAN ACID METABOLISM IN MESEMBRYANTHEMUM CRYSTALLINUM. 

Mesembryanthemum crystallinum changes its mode of carbon assmilation from C3 photosynthesis to CAM when water stressed by high soil salinity (1). Such a shift in photosynthetic pathway is accompanied by marked increases in extractable activities of several enzymes including PEP carboxylase and NADP-malic enzyme. 

Fig. 2.6. Lomasome-like vesicles in the cells of Mesembryanthemum crystallinum in the CAM stage. F= Vacuole, LO = Lomasome, T=Tonoplast, C = Chloroplast (from Kramer and von...

CAM cell vacuoles often appear filled with precipitations, probably due to tannins or tannin-like substances (see Fig. 2.5). Electron micrographs of von Willert and Kramer (1972) suggest membranous compartmentation within the vacuoles of Mesembryanthemum crystallinum. Also bladder-like vesicles extending from the cytoplasm into the vacuole were seen in the mesophyll cells of the same species. These vesicles consist of an envelope (double membrane) which encloses rather densely packed tubuli (Fig. 2.6) resembling lomasomes and interpreted as such by von Willert and Kramer. At the moment, there is no clear suggestion if these lomasome-like vesicles fulfill a specific role in CAM of Mesembryanthemum crystallinum. 

Winter et al. (1974), studying Mesembryanthemum crystallinum, showed that the NaCl-enhanced dark CO2 fixation was accompanied by relatively more organic acid synthesis, and not amino acid synthesis. Hence, this aizoid differs from the halophytic chenopods studied by Webb and Burley (1965). 

Ting, 1971). Winter and von Willert (1972), Kramer and von Willert (1972) reported that Mesembryanthemum crystallinum could be induced to take up CO2 in the dark and accumulate malic acid if irrigated with NaCl (see Fig. 5.8). The increased malic acid accumulation was accompanied by an increase in PEP carboxylase. The physiological basis for CAM induction is not entirely clear, but may be related to unfavorable water potentials accompanying the NaCl treatment (Winter, 1973,1974 for more detail cf. Chap.4.3.4.2). 

As indicated earlier (Chap. 4.2.1.1), inorganic phosphate (Pi) lowers the inhibition of PEP carboxylase by malate and NaCl in in vitro systems (von Willert, 1975 b, c). Von Willert found that in Mesembryanthemum crystallinum the induction of CAM during irrigation with NaCl solutions is accompanied with an increase in the Pi level of the leaves. Therefore, it was argued that inorganic phosphate protected PEP carboxylase from the inhibition of NaCl and malic acid. Thus, CAM could operate in salt-stressed Mesembryanthemum plants in spite of increasing NaCl and malic acid levels in the cells. It should be noted, however. 

As indicated by kinetic and electrophoretic studies in Mesembryanthemum crystallinum, not only total PEP carboxylase activity, but also the properties of the enzyme undergo alterations both during induction of CAM and during its reversion (von Willert, 1975 Treichel et al., 1974 von Willert et al., 1976b). However, more experiments with more species are desired before generalizations. For example, preliminary experiments on Sedum acre (Kluge and Knopf, unpublished) provided no indication of alterations in the kinetic or electrophoretic behavior of PEP carboxylase during CAM induction by water stress. 

Grown under laboratory conditions, Mesembryanthemum crystallinum and M. nodiflorum (see Winter and von Willert, 1972 Treichel and Bauer, 1974) had C estimates of — 22.7%o and — 22.0%o, which is in the range of C3 plants, in spite of nocturnal malic acid accumulation. This suggests that the C composition alone does not necessarily indicate CAM (see also Kluge, 1977 b). 

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