Response of carbon and nitrogen-rich metabolites to nitrogen deficiency in PSARK∷IPT tobacco plants

• Published in: Plant physiology and biochemistry 2012-08, Vol.57, p.231-237
• Main Authors: Rubio-Wilhelmi, María del Mar, Sanchez-Rodriguez, Eva, Leyva, Rocio, Blasco, Begoña, Romero, Luis, Blumwald, Eduardo, Ruiz, Juan Manuel
• Format: Article
• Language: English
• Subjects: Alkyl and Aryl Transferases - metabolism; Biological and medical sciences; carbon; Carbon - metabolism; Cytokinins; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; genes; metabolism; metabolites; Nicotiana - genetics; Nicotiana - metabolism; Nitrates - metabolism; nitrogen; Nitrogen - deficiency; Nitrogen - metabolism; Phenolic compounds; Plant physiology and development; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; Polyamines; Proline; Reactive oxidative species; stress response; tobacco
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2012.06.004

Wild type (WT) and transgenic tobacco plants expressing isopentenyltransferase (IPT), a gene coding the rate-limiting step in cytokinin (CKs) synthesis, were grown under limited nitrogen (N) conditions. Here, we analyse the possible effect of N deficiency on C-rich compounds such as phenolic compounds, as well as on N-rich compounds such as polyamines (PAs) and proline (Pro), examining the pathways involved in their synthesis and degradation. N deficiency was found to stimulate phenolic metabolism and increase these compounds both in PSARK:IPT as well as in WT tobacco plants. This suggests that nitrate (NO3−) tissue concentration may act as a signal triggering phenolic compound accumulation in N deficiency plants. In addition, we found the maintenance of PAs in the WT plants would be correlated with the higher stress response to N deficiency. On the contrary, the reduction of free PAs and Pro found in the PSARK∷IPT plants subjected to N deficiency would indicate the operation of an N-recycling mechanism that could stimulate a more efficient N utilization in PSARK∷IPT plants. ► WT and PSARK∷IPT tobacco plants were grown under limited N conditions. ► NO3− may act as a signal triggering phenols accumulation in N deficiency plants. ► Maintenance of PAs in WT plants would be correlated with stress response to N deficiency. ► Reduction of free PAs and Pro in the PSARK:IPT plants subjected to N deficiency. ► PSARK:IPT plants would activate N-recycling mechanisms.