SRA

Nitrogen (N) is an essential macronutrient for crops. Plants developed several responses to N fluctuations, thus optimizing the root architecture in response to N availability. Nitrate and ammonium are the main N inorganic forms taken up by plants and act as both nutrients and signals, affecting gene expression and plant development. In this study, RNA-sequencing was applied to gain comprehensive information on the pathways underlying the response of maize root, pre-treated in an N-deprived solution, to the provision of nitrate or ammonium. To assess the physiological response to these nutrients the shoot and root growth, the leaf pigment content and the amino acid amount in root and shoot were assessed. The analysis of the transcriptome shows that nitrate and ammonium regulate overlapping and distinct pathways, thus leading to different responses. NH4+ activates the response to stress, while NO3- acts as a negative regulator of transmembrane transport. Both the N-source repress genes related to the cytoskeleton and reactive oxygen species detoxification. Moreover, the presence of ammonium induces the accumulation of anthocyanins, while reduces biomass and chlorophyll and flavonoids accumulation. The profiles observed for hydrolysed and free amino acids highlighted common and distinct features in response to the two nitrogen forms. Overall design: Illumina RNA-Seq analysis of maize root apexes samples collected from seedlings grown for 24 h in nutrient solution supplied with 1mM NO3- or 1mM NH4+ compared to negative controls grown in a N-deprived nutrient solution. 3 days old maize B73 inbreed seedlings were treated for 24 h prior to roots collection and RNA extraction. 3 biological replicates per condition were produced, each composed by 10-15 plants.