title: Putrescine accumulation confers drought tolerance in transgenic Arabidopsis plants over-expressing the homologous Arginine decarboxylase 2 gene.
abstract: In Arabidopsis, a model genus missing a functional ornithine decarboxylase pathway, most of the key genes involved in polyamine biosynthesis are duplicated. This gene redundancy has been related to the involvement of certain gene isoforms in the response to specific environmental stimuli. We have previously shown that drought stress induces Arginine decarboxlase 2 expression, while transcript levels for Arginine decarboxlase 1 remain constant. Accumulation of putrescine and increased arginine decarboxlase activity (EC 4.1.1.19) levels in response to different abiotic stresses have been reported in many different plant systems, but the biological meaning of this increase remains unclear. To get a new insight into these questions, we have studied the response to drought of transgenic Arabidopsis thaliana lines constitutively expressing the homologous Arginine decarboxlase 2 gene. These lines contain high levels of putrescine with no changes in spermidine and spermine content even under drought stress. Drought tolerance experiments indicate that the different degree of resistance to dehydration correlates with Put content. Although no significant differences were observed in the number of stomata between wild-type and transgenic plants, a reduction in transpiration rate and stomata conductance was observed in the ADC2 over-expressor lines. These results indicate that one of the mechanisms involved in the drought tolerance of transgenic plants over-producing Put is related to a reduction of water loss by transpiration.
authors.affiliation: Unitat de Fisiologia Vegetal, Facultat de Farmàcia, Universitat de Barcelona, Diagonal 643, 08028-Barcelona, Spain.
authors.forename: Rubén
authors.initials: R
authors.lastname: Alcázar
authors.forename: Joan
authors.initials: J
authors.lastname: Planas
authors.forename: Triambak
authors.initials: T
authors.lastname: Saxena
authors.forename: Xavier
authors.initials: X
authors.lastname: Zarza
authors.forename: Cristina
authors.initials: C
authors.lastname: Bortolotti
authors.forename: Juan
authors.initials: J
authors.lastname: Cuevas
authors.forename: Marta
authors.initials: M
authors.lastname: Bitrián
authors.forename: Antonio F
authors.initials: AF
authors.lastname: Tiburcio
authors.forename: Teresa
authors.initials: T
authors.lastname: Altabella
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism*; D055864:Droughts; D015870:Gene Expression; D017343:Genes, Plant; D054046:Plant Stomata; D018526:Plant Transpiration / Q000235:genetics; D030821:Plants, Genetically Modified; D011700:Putrescine / Q000378:metabolism*; D013095:Spermidine / Q000378:metabolism; D013096:Spermine / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D013096:Spermine; D002262:Carboxy-Lyases; C019722:arginine decarboxylase; D013095:Spermidine; D011700:Putrescine