Mecanismos moleculares de resposta ao estresse por excesso de ferro em arroz

Abstract

Iron (Fe) is an essential nutrient for the growth and development of plants. However, the availability of this element varies due to ground conditions and cropping system. Either the excessive absorption or the deficiency of this element may cause toxicity in plants leading to a loss of the productivity. In Rio Grande do Sul, problems from the excess of iron have been reported, and the use of tolerant cultivars becomes an important strategy to address this issue. Thus, the more information regarding the mechanisms that confer this tolerance in plants is known, the easier their application in breeding programs becomes. The aim of this work was to study the transcriptome of a Brazilian rice cultivar characterized as tolerant to excess of iron (BRS Querência). For this, the plants were submitted to stress conditions (300 mg L-1 Fe+2) in the V3 stage for 24 hours, the RNA of the leaves was extracted and sequenced by RNA-Seq technology. Such a study was divided into the following chapters: I) Dealing with iron metabolism in rice: from breeding aiming at stress tolerance to biofortification (Review article submitted to the Genetics and Molecular Biology); II) Genome-wide transcriptional profile of rice reveals new genes involved in tolerance to iron (Article probable submission to the The Plant Genome); III) Stress response of plants: the role of alternative splicing (Review article probable submission to the Genome); IV) The search for more tolerant rice: how high concentrations of iron affect the alternative splicing? (Article accepted by Transcriptomics: Open Access). The study enabled the identification of several differentially expressed genes. Among these, we highlight the activation of genes encoding proteins responsible for iron homeostasis (transport and storage) the heat shock proteins and proteins of photosystem II. Furthermore, we have highlighted the repression of genes encoding the hormone metabolism and signaling proteins. The alternative splicing analysis provided the identification of a profile change in the cell on stress condition, having reduction in the quantity of the junction sites as well as in the number of events. The results represent an important step in the understanding of tolerance strategies performed by this cultivar, assisting in the identification of potential target genes for use by breeding programs.