Present address: AFRC Institute of Arable Crops Research, Biochemistry and Physiology Department, Rothamsted Experimental Station, Harpenden, Herts., AL5 2JQ, UK and to whom correspondence should be addressed.
The stimulation of CAM activity in Mesembryanthemum crystallinum in nitrate and phosphate-deficient conditions
Article first published online: 28 APR 2006
Volume 114, Issue 3, pages 391–398, March 1990
How to Cite
PAUL, M. J. and COCKBURN, W. (1990), The stimulation of CAM activity in Mesembryanthemum crystallinum in nitrate and phosphate-deficient conditions. New Phytologist, 114: 391–398. doi: 10.1111/j.1469-8137.1990.tb00406.x
- Issue published online: 28 APR 2006
- Article first published online: 28 APR 2006
- (Received 20 July 1989; accepted 20 October 1989)
- Mesembryanthemum crystallinum;
- nutrient deficiency
Plants of Mesembryanthemum crystallinum L. were grown from seed in phosphate-sufficient and phosphate-deficient conditions. Separate plants were subjected to nitrate deficiency by removing nitrate from the rooting medium of previously nitrate-sufficient plants. Subsequently, they were also irrigated with 400 mM NaCl to induce CAM. Plants of M. crystallinum with induced CAM that had been grown in complete nutrient medium were deinduced by rehydration.
Nitrate and phosphate deficiencies caused enhanced CAM activity prior to salt treatments. After salinisation, phosphate deficiency also caused higher background levels of malate. Prolonged nitrate deficiency reduced CAM activity.
Endogenous P1 levels in phosphate-sufficient plants correlated with CAM activity. However in phosphate-deficient plants CAM occurred without a significant rise in P1 content. Levels of endogenous P1 appeared more related to nitrate deficiency than to CAM or salt treatment. Nitrate and phosphate deficiencies and salt treatment could all cause a nitrate deficiency within the leaf, causing high endogenous P1 when available in the rooting medium. It is speculated that a change in nitrogen status could play a role in the initiation of CAM induction in M. crystallinum. A further possibility is that CAM could be induced by reduced water potential due to dehydration and increased ion content in saline conditions, and by an inhibition of growth and concomitant accumulation of solutes in phosphate- and nitrate-deficient conditions.