Expression of transcription factors involved with dehydration in contrasting rice genotypes submitted to different levels of soil moisture

Abstract

Plant tolerance to abiotic stresses, such as water deficit, is triggered by complex multicomponent signaling pathways. One of the plant responses to stress conditions is expression of a large number of genes whose products are involved in various adaptive functions. Transcription factors (TFs) are important regulators of gene expression, modulating the transcription initiation rate of target genes; they are critical components in signal transduction in response to abiotic stress. Our hypothesis is that genotypes with contrasting tolerance signal water deficit through TFs (10 genes of the DREB family and bZIP) with differing degrees of expression. We believe that these genes will have greater expression in the flooded genotype because drought is an atypical condition in these plants. We tested two rice (Oryza sativa) genotypes: BRS Querência (flooded) and AN Cambará (dryland). When they reached stage V5, the plants were submitted to water deficit, at different levels of soil moisture, 20%, 10% and recovery. In general, we observed that expression varies according to the soil moisture and the genotype. In addition, the coexpression analysis generated seven cluster interactions with several genes. Our hypothesis was confirmed in part; the contrasting genotypes gave different degrees of expression; however, we ca not affirm that the flooded genotype has more significant responses in dry soil because there were variations in expression demonstrating oscillation in metabolism, and the data do not allow us to associate expression with greater drought tolerance.