The ice plant cometh: Lessons in abiotic stress tolerance

Mesembryanthemum crystallinum, the common ice plant, provides a model for the developmentally and environmentally inducible shift from C3 photosynthesis to Crassulacean acid metabolism. Study of its halophytic (salt tolerant) nature has also yielded crucial insights into abiotic stress biology. In addition, the ice plant serves as an anchor species for genomic studies in the order Caryophyllales in which very few species have been studied at the molecular genetic level. Large-scale expressed sequence tag projects allow comparisons of gene expression in different tissues, organs, and developmental states in stressed and unstressed plants during the life cycle. Microarray analyses pinpoint transcripts affected by abiotic stresses to functionally characterize the essential elements that constitute natural abiotic stress tolerance. Mesembryanthemum features advantages of a small genome, an emerging transformation system, a growing mutant collection, and the potential for bioremediation of salinized soil because of its ability to efficiently sequester salts into vegetative tissues. Disadvantages are the plant's potentially large size at flowering, a 4-month life cycle under growth chamber conditions, and extreme response plasticity to minute perturbations in the environment.