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Publication Type J
Authors Vernon, D. M. and H. J. Bohnert
Title Increased Expression of a Myoinositol Methyl Transferase in Mesembryanthemum-Crystallinum Is Part of a Stress Response Distinct From Crassulacean Acid Metabolism Induction
Source Plant Physiology
Author Keywords 2312_92 1 lateral roots of 2 desert succulents, hydraulic conductivity, crassulacean acid metabolism, drying soil, stem water storage, c-4 plants salt stress, phosphoenolpyruvate carboxylase, messenger-rna
Abstract The facultative halophyte Mesembryanthemum crystallinum responds to osmotic stress by switching from C3 photosynthesis to Crassulacean acid metabolism (CAM). This shift to CAM involves the stress- initiated up-regulation of mRNAs encoding CAM enzymes. The capability of the plants to induce a key CAM enzyme, phosphoenolpyruvate carboxylase, is influenced by plant age, and it has been suggested that adaptation to salinity in M. crystallinum may be modulated by a developmental program that controls molecular responses to stress. We have compared the effects of plant age on the expression of two salinity-induced genes: Gpdl, which encodes the photosynthesis- related enzyme glyceraldehyde 3-phosphate dehydrogenase, and Imtl, which encodes a methyl transferase involved in the biosynthesis of a putative osmoprotectant, pinitol. Imtl mRNA accumulation and the accompanying increase in pinitol in stressed Mesembryanthemum exhibit a pattern of induction distinct from that observed for CAM-related genes. We conclude that the molecular mechanisms that trigger Imtl and pinitol accumulation in response to salt stress in M. crystallinum differ in some respects from those that lead to CAM induction. There may be multiple signals or pathways that regulate inducible components of salinity tolerance in this facultative halophyte.
Year Published 1992
Volume 99
Issue 4
Beginning Page 1695-1698
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