Molecular basis of plant resistance to soil salinity: characterization of NADPH oxidase (RBOH) genes in halophyte Eutral salsugineum

Summary: The research proposed in the framework of scientific internship concern the genomic identification, characterization and functional analysis of NADPH oxidase (RBOH) genes in the halophyte of E. salsugineum. This species belonging to Brassicaceae is a model for studying plant responses to abiotic stresses and its genome has been sequenced. RBOH proteins are membrane enzymes that reduce oxygen to O2 - using NADPH as an electron donor. The resulting O2.- is subject to dissmission leading to the creation of H2O2. Research conducted by Sewelam et al. (2014) on A. thaliana mutants characterized by increased production of H2O2 in chloroplasts or peroxisomes showed that this compound regulates the expression of many genes and its effect depends on the site of formation in the cell. Earlier work on A. thaliana also indicates that the greater production of H2O2 in chloroplasts during stress induces its formation also in the apoplast (Mullineaux et al. 2006). The structure of RBOH genes in E. salsugineum, their expression profile in response to NaCl stress and regulation by stress hormones as well as enzymatic activity of proteins have not been described so far. As part of this project, a research stay is planned at the Institute of Molecular Physiology and Plant Biotechnology at the University of Bonn in Germany, in a research group led by prof. Dorothea Bartels. The research topic pursued by this team is the search for the relationship between the structure of genes, their regulation and the resistance of plants to abiotic stress. The main objectives of the research are: (1) bioinformatic analysis of gene structure (including the rhythmic sequence) of RBOH in E. salsugineum, determination of protein sequences and identification of differences in relation to RBOH proteins in Arabidopsis thaliana; (2) analysis of the expression level of selected RBOH genes in E. salsugineum and A. thaliana leaves subjected to NaCl stress; (3) assessment of the contribution of stress hormones, ABA and ethylene, in the regulation of EsRBOH expression; (4) assessment of the level of activity of RBOH enzymes in E. salsugineum and A. thaliana leaves under NaCl stress Achieving the assumed goals will allow to verify the following research hypotheses: (1) there are differences in the structure of RBOH proteins and genes encoding them between E. salsugineum and A. thaliana; (2) RBOH genes in E. salsugineum have higher expression than in A. thaliana; (3) EsRBOH gene expression is regulated by ABA and ethylene; (4) RBOH proteins in E. salsugineum are more active than in A. thaliana