Biosphere nitrogen is subjected to a rapid turnover by denitrification, thus, the maintenance of nitrogen balance requires atmospheric nitrogen (N2) fixation which in short, can be provided either by chemical reduction or by biological fixation. Legumes and actinorhizal plants are able to establish root nodule symbiosis with N2-fixing bacteria, Rhizobium and Frankia, respectively.The enhanced ability of actinorhizal plants to cope with extreme environmental conditions has been attributed to their capacity to establish N2-fixing root-nodule symbioses with Frankia bacteria. However, research on this topic is only now emerging. At the molecular level, our group initiated pioneering research on the analysis of plant defense/stress-response genes in the model actinorhizal species Casuarina glauca (Fortunato et al 2007, Santos et al 2008, Santos et al 2010).
We will evaluate the impact of salt stress at the morphological, physiological and (bio) chemical level in order to determine major changes in photosynthesis, antioxidative system and membrane stability, the first putative “targets” of stress damage. In parallel, the effects of salt stress on water use, N2-fixation efficiency and plant growth will also be determined. This set of analyses, reinforced by a dedicated bioinformatics infrastructure, will allow for the identification of key points for a larger analysis at the proteome level, complementary to the transcriptomics approaches established at Institut de Recherche pour le Développement (IRD, Montpellier, France). We anticipate that the sum of these analyses will serve to elucidate the most important mechanisms used by the plant to cope with salinity as well as to determine to which extent symbiosis with Frankia contributes to salt stress tolerance. With this proposal, we intend to complement and broaden previous studies, thus contributing for the progress of actinorhizal plant research, particularly regarding the impact of salt stress in C. glauca.
Science and Technology Foundation (FCT - PTDC/AGR-FOR/4218/2012).
Project Leader: Ana Isabel Faria Ribeiro, Instituto de Tecnologia Química e Biológica Universidade Nova de Lisboa (ITQB/UNL).
Partners Instituto de Tecnologia Química e Biológica (ITQB/UNL); Department of Plant Pathology, Michigan State University (MSU); Fundação da Faculdade de Ciências da Universidade de Lisboa (FFC/FC/UL); Instituto de Investigação Científica e Tropical (IICT/MNE); Instituto Nacional de Recursos Biológicos, I.P. (INRB/MADRP); University of Stockholm - Department of Botany, (SU).