Mesembryanthemum crystallinum is a prostrate succulent plant native to Africa, Sinai and southern Europe, and naturalized in North America, South America and Australia. I need the detailed internal processes behind the physiological adaptations seen in it.
The sun beats down relentlessly on the soil of South Africa. If you do not want to die of thirst, you have to resort to some expedient. The Mesembryanthemum crystallinum can be considered a "specialist in the supply of water."
It grows on sandy soils, clay, even where salt comes to cover an area up to 0.7 m² in the hot sun.
Its secret is the leaves, green or red. Are thick, juicy, covered with small blisters filled with clear water that seem tiny and bright drops of dew or frost crystals. From July to September the ice plant is covered with numerous flowers that range from white to red with petals radiating.
This abundance contrasts with the root, which is only a few inches long and gives the impression that its function is only to anchor the plant to the ground rather than supply it with water.
From dr. Hauschka
Physiological adaptation, due to its extreme stress tolerance, drought and high salinity resistance, and its ability to shift from C3 photosynthesis to CAM in response to environmental stresses or as part of its developmental programme. At present minor attention has been paid to elevated light and UV rays effects on ice plant metabolism and its adaptation. Young ice plants have been exposed to 5 W m -2 UV-B light (3 to 9 kJ m -2 d -1 UV-B BE ) for 10 – 30 min. On the next day leaves and roots have been collected, frozen and used for determination of total contents of osmolytes, chlorophyll, polyamines and free amino acid composition. A decrease in chlorophyll and net CO2 assimilation gave evidence that ice plant had high sensitivity to UV-B irradiation. The absence of proline in leaves accompanied with other modifications in free amino acids composition in both leaves and roots, the slight stimulation of polyamine biosynthesis as well as the lack of cadaverine in roots could be considered as indications for the damage of ice plants due to the poor metabolic adaptation to stress caused by UV-B irradiation.
http://www.bio21.bas.bg/ipp/gapbfiles/pisa-06/06_pisa_33-44.pdf
The ability of Mesembryanthemum crystallinum and M. nodiflorum to switch from C3 photosynthesis to CAM enables plants to adapt to high saline and arid situations and to withstand stressful conditions. The ability to accumulate salt, which is leached to the soil on death, and to suppress growth of other species, provides us with experimental potential and ability to test movement of salt in riparian areas. Changes in water table levels and differing environmental flow regimes with consequent effects on salinity levels may affect the distribution of these Mesembryanthemum species, and other native species associated with them.
The facultative CAM plant Mesembryanthemum crystallinum displays a differential organ level response to salt stress while still engaged in C3 photosynthesis [53]. Subjecting plants to 400 mM NaCl resulted in an approximately two fold increase in the transcript levels of subunits A, B, and the proteolipid in roots prior to the shift to Crassulacean acid metabolism. Fully expanded leaves exhibited an increase only for the proteolipid mRNA, an increase of approximately three fold over non salt stressed plants [54]. Cell suspension cultures when subjected to salt stress exhibited increase in activity of both P-Type and V-Type ATPases without concomitant increase in protein levels [55]. Transcript levels of subunit E of the V-ATPase in Mesembryanthemum crystallinum were recently shown to increase in leaves but not roots of salt stressed plants with a concomitant increase in protein levels in leaves
http://www.biomedcentral.com/1471-2229/2/3/
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