Expression of Genes Involved in Nitrate Signaling and Metabolism in Peach Roots in Response to Elevated Levels of Nitrate

Abstract

Nitrate is a major source of nitrogen, and it also acts as a signaling molecule that has an impact on gene expression associated with nitrogen uptake, metabolism and organ development. During fertilization, plants need to adapt to increased levels of available nitrogen. In this study, we have analyzed gene expression changes during this process using seedlings from peach trees, an important horticultural model plant. The results show that nitrate affects a broad range of genes. Except for carbon metabolism, nitrate affects genes associated with many biological plant processes, such as the biosynthesis of secondary metabolites and plant–pathogen interactions, amongst others. Overall, 1,247 genes were downregulated, 460 genes were upregulated by 10 mM nitrate in roots and 32,296 candidates for new transcripts were found. These results suggest that peach gene transcripts may not have been fully predicted. In this study, we found 12 nitrate transporters, 13 DNA-binding single-finger transcription factors, 6 sucrose non-fermenting-1-related protein kinase 1 and 2 isopentenyl transferase homologous genes. Most of these were repressed by 10 mM nitrate in root tissue compared with 0.5 mM nitrate. These results differed from earlier studies in other plants that showed some genes did not have significant sequence similarity. Future studies will need to characterize the functional roles of the genes with unknown functions, and the results obtained in this work will need to be validated using other expression analysis tools.