Ammonium formation and assimilation in P-SARK::IPT tobacco transgenic plants under low N

作者：del Mar Rubio Wilhelmi Maria; Sanchez Rodriguez Eva; Angel Rosales Miguel; Blasco Begona; Jose Rios Juan; Romero Luis; Blumwald Eduardo; Manuel Ruiz Juan

来源：Journal of Plant Physiology, 2012, 169(2): 157-162.

DOI：10.1016/j.jplph.2011.09.011

• Amino acids
• Cytokinins
• Nicotiana tabaccum
• Nitrate reductase
• Photorespiration

Wild Type (WT) and transgenic tobacco plants expressing isopentenyltransferase (IPT), a gene encoding the enzyme regulating the rate-limiting step in cytokinins (CKs) synthesis, were grown under limited nitrogen (N) conditions. We analyzed nitrogen forms, nitrogen metabolism related-enzymes, amino acids and photorespiration related-enzymes in WT and P-SARK::IPT tobacco plants. Our results indicate that the WT plants subjected to N deficiency displayed reduced nitrate (NO3-) assimilation. However, an increase in the production of ammonium (NH4+), by the degradation of proteins and photorespiration led to an increase in the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle in WT plants. In these plants, the amounts of amino acids decreased with N deficiency, although the relative amounts of glutamate and glutamine increased with N deficiency. Although the transgenic plants expressing P-SARK::IPT and growing under suboptimal N conditions displayed a significant decline in the N forms in the leaf, they maintained the GS/GOGAT cycle at control levels. Our results suggest that, under N deficiency, CKs prevented the generation and assimilation of NH4+ by increasing such processes as photorespiration, protein degradation, the GS/GOGAT cycle, and the formation of glutamine.

• 出版日期2012-1-15