Transcriptional modulation of genes encoding nitrate reductase in maize (Zea mays) grown under aluminum toxicity
The free aluminum (Al) content in soil can reach levels that are toxic to plants, and this has frequently limited increased productivity of cultures. Four genes encoding nitrate reductase (NR) were identified, named ZmNR1–4. With the aim of evaluating NR activity and the transcriptional modulation of the ZmNR1, ZmNR2, ZmNR3, and ZmNR4 genes in leaves, 30-day-old hybrid maize BRAS 3010 plants were irrigated with a solution of Al2(SO4)3.18H2O for 16 days. The transcriptional levels of ZmNR2, ZmNR3, and ZmNR4 and NR activity will exhibit standard changes similar in the leaves, where, from the second week of stress onwards, there was a decrease in enzymatic activity and in the accumulation of transcripts. An increase ZmNR1 mRNA levels were observed, indicating that this gene may be associated with other metabolic pathways. This study resulted in the identification and characterization of different genes that encode NR and are involved in nitrogen metabolism in maize, in which the ZmNR2, ZmNR3, and ZmNR4 genes regulate the activity of NR in response to aluminum stress. The characterization of these genes may help in our understanding of the genetic-molecular and physiological mechanisms of maize subjected to aluminum stress.
Keywords: Abiotic stress, Al, gene expression, nitrogen, metal toxicity, mineral nutrition