Salt stress responses in nodules of two actinorhizal plant species, Datisca glomerata and Casuarina glauca
(English)Manuscript (preprint) (Other academic)
Soil salinization is a factor in declining crop yields worldwide. Salt tolerance depends on the plant antioxidant defense system. Nitrogen availability is essential to agriculture and land reclamation. Some nitrogen-fixing bacteria can enter symbioses with higher plants - rhizobia with legumes, and Frankia strains with actinorhizal plants. In both symbioses, the plants form special organs, root nodules, wherein they host the bacterial endosymbionts. Rhizobial nitrogen fixation in legume nodules in combination with the oxygen protection system, leads to the production of reactive oxygen species (ROS) which require a high activity of antioxidant defense, a fact which has been thought to be responsible for the salt sensitivity of legumes. Actinorhizal oxygen protection systems for bacterial nitrogen fixation in nodules are more diverse, and actinorhizal plants tend to show salt tolerance. In this study, the antioxidant defense systems were examined in two actinorhizal species, Casuarina glauca which has an oxygen protection system similar to those of legumes, and Datisca glomerata which has a different system. The results indicated that the subcellular location of hydrogen peroxide production differed in infected cells of both plants, namely, the cytosol in C. glauca and the symbiotic bacteria in D. glomerata. Studies of enzymes and metabolites involved in antioxidant defense indicated that the glutathione-ascorbate cycle is far more active in D. glomerata than in C. glauca nodules, while the latter have higher catalase activities.
reactive oxygen species, antioxidant system, ascorbate peroxidase, glutathione
Research subject Plant Physiology
IdentifiersURN: urn:nbn:se:su:diva-30846OAI: oai:DiVA.org:su-30846DiVA: diva2:274362