Metabolic engineering of osmoprotectant accumulation in plants.
Drought and salinity are among the worst scourges of agriculture. One effective mechanism to reduce damage from these stresses is the accumulation of high intracellular levels of osmoprotectant compounds. These compounds include proline, ectoine, betaines, polyols, and trehalose and have evolved in many different organisms. Since some crop plants have low levels of these osmoprotectants or none at all, engineering osmoprotectant biosynthesis pathways is a potential way to improve stress tolerance. First-generation engineering work--much of it with single genes--has successfully introduced osmoprotectant pathways into plants that lack them naturally, and this has often improved stress tolerance. However, the engineered osmoprotectant levels are generally low and the increases in tolerance commensurately small. To get beyond trace levels of osmoprotectants and marginal tolerance increments we need to use flux measurements to diagnose what limits osmoprotectant levels in engineered plants and to use iterative cycles of engineering to overcome these limitations.
Rontein
Denis
D
Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611, USA.
Basset
Gilles
G
Hanson
Andrew D
AD
D000599:Amino Acids, Diamino / Q000096:biosynthesis; D001622:Betaine / Q000378:metabolism; D019610:Cytoprotection; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D009997:Osmotic Pressure; D018521:Plant Physiological Phenomena; D010944:Plants / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D015202:Protein Engineering; D014199:Trehalose / Q000096:biosynthesis
D000599:Amino Acids, Diamino; D001622:Betaine; C045628:ectoine; D014199:Trehalose