title: Modulated fatty acid desaturation via overexpression of two distinct omega-3 desaturases differentially alters tolerance to various abiotic stresses in transgenic tobacco cells and plants.
abstract: Changes in the degree of fatty acid (FA) desaturation are implicated in plant responses to various abiotic stresses, including heat, salt and drought. However, it is still not known whether decreased levels of linolenic acid, found in many plants subjected to salt and drought stress, reflect a mechanism of defence or damage. We addressed this question by generating tobacco cells and plants ectopically overexpressing two FA desaturases: the cytosolic FAD3 or the plastidic FAD8. A remarkable increase in the ratio of total linolenic to linoleic acids resulted from overexpression of FAD3, whereas ectopic overexpression of FAD8 induced an increased ratio mainly in the plastidic lipids. Here we present evidence that overexpressing FAD8 imposes much greater heat sensitivity than does FAD3 overexpression, in both cultured cells and whole plants. Overexpression of either FAD3 or FAD8 increases tolerance to drought in tobacco plants and to osmotic stress in cultured cells. These findings suggest that a drought-induced decreased level of linolenic acid reflects damage. Our results point to the potential of exploiting FAD overexpression as a tool to ameliorate drought tolerance.
authors.affiliation: Institute of Horticulture, ARO, The Volcani Center, Bet Dagan, Israel.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.forename: Rivka
authors.initials: R
authors.lastname: Barg
authors.forename: Mingan
authors.initials: M
authors.lastname: Yin
authors.forename: Yardena
authors.initials: Y
authors.lastname: Gueta-Dahan
authors.forename: Alicia
authors.initials: A
authors.lastname: Leikin-Frenkel
authors.forename: Yehiam
authors.initials: Y
authors.lastname: Salts
authors.forename: Sara
authors.initials: S
authors.lastname: Shabtai
authors.forename: Gozal
authors.initials: G
authors.lastname: Ben-Hayyim
mesh_terms: D002478:Cells, Cultured; D003890:Desiccation; D044943:Fatty Acid Desaturases / Q000235:genetics* / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006358:Hot Temperature; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics; D030821:Plants, Genetically Modified; D011092:Polyethylene Glycols; D013012:Sorbitol; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics*; D014867:Water / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D010940:Plant Proteins; D014867:Water; D011092:Polyethylene Glycols; D013012:Sorbitol; D044943:Fatty Acid Desaturases; C078565:omega-3 fatty acid desaturase