Improved drought tolerance without undesired side effects in transgenic plants producing trehalose.
Most organisms naturally accumulating trehalose upon stress produce the sugar in a two-step process by the action of the enzymes trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP). Transgenic plants overexpressing TPS have shown enhanced drought tolerance in spite of minute accumulation of trehalose, amounts believed to be too small to provide a protective function. However, overproduction of TPS in plants has also been found combined with pleiotropic growth aberrations. This paper describes three successful strategies to circumvent such growth defects without loosing the improved stress tolerance. First, we introduced into tobacco a double construct carrying the genes TPS1 and TPS2 (encoding TPP) from Saccharomyces cerevisiae. Both genes are regulated by an Arabidopsis RuBisCO promoter from gene AtRbcS1A giving constitutive production of both enzymes. The second strategy involved stress-induced expression by fusing the coding region of ScTPS1 downstream of the drought-inducible Arabidopsis AtRAB18 promoter. In transgenic tobacco plants harbouring genetic constructs with either ScTPS1 alone, or with ScTPS1 and ScTPS2 combined, trehalose biosynthesis was turned on only when the plants experienced stress. The third strategy involved the use of AtRbcS1A promoter together with a transit peptide in front of the coding sequence of ScTPS1, which directed the enzyme to the chloroplasts. This paper confirms that the enhanced drought tolerance depends on unknown ameliorated water retention as the initial water status is the same in control and transgenic plants and demonstrates the influence of expression of heterologous trehalose biosynthesis genes on Arabidopsis root development.
Karim
Sazzad
S
School of Life Sciences, University of Skövde, Box 408, 541 28, Skövde, Sweden.
Aronsson
Henrik
H
Ericson
Henrik
H
Pirhonen
Minna
M
Leyman
Barbara
B
Welin
Björn
B
Mäntylä
Einar
E
Palva
E Tapio
ET
Van Dijck
Patrick
P
Holmström
Kjell-Ove
KO
D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics; D002736:Chloroplasts / Q000378:metabolism; D005818:Genetic Engineering; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology*; D011401:Promoter Regions, Genetic; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D014026:Nicotiana / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development; D014199:Trehalose / Q000096:biosynthesis*; D014867:Water / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000235:genetics
D029681:Arabidopsis Proteins; D029701:Saccharomyces cerevisiae Proteins; C078703:rab18 protein, Arabidopsis; D014867:Water; D014199:Trehalose; D005964:Glucosyltransferases; C023180:trehalose-6-phosphate synthase; C023178:trehalose-phosphatase; D010744:Phosphoric Monoester Hydrolases; D020691:rab GTP-Binding Proteins; D012273:Ribulose-Bisphosphate Carboxylase