BUSCADOR RECOLECTA

Digital.CSIC. Repositorio Institucional del CSIC

oai:digital.csic.es:10261/191230

Ammonium sensitivity of plants is a worldwide problem, constraining crop production. Prolonged application of ammonium as the sole nitrogen source may result in physiological and morphological disorders that lead to decreased plant growth and toxicity. The main causes of ammonium toxicity/tolerance described until now include high ammonium assimilation by plants and/or low sensitivity to external pH acidification. The various ammonium transport-related components, especially the non-electrogenic influx of NH3 (related to the depletion of 15N) and the electrogenic influx of NH4+, may contribute to ammonium accumulation, and therefore to NH3 toxicity. However, this accumulation may be influenced by increasing K+ concentration in the root medium. Recently, new insights have been provided by “omics” studies, leading to a suggested involvement of GDP mannose-pyrophosphorylase in the response pathways of NH4+ stress. In this review, we highlight the cross-talk signaling between nitrate, auxins and NO, and the importance of the connection of the plants’ urea cycle to metabolism of polyamines. Overall, the tolerance and amelioration of ammonium toxicity are outlined to improve the yield of ammonium-grown plants. This review identifies future directions of research, focusing on the putative importance of aquaporins in ammonium influx, and on genes involved in ammonium sensitivity and tolerance., The authors acknowledge the support of research grants AGL2014-52396-P from the Spanish Ministry of Economy and Competitiveness (MINECO) and PTDC/BIA-BEC/099323/2008 and PTDC/BIA-ECS/122214/2010 from the Portuguese Fundação para a Ciência e Tecnologia (FCT). RE received a JAE-Doc-2011-046 fellow from the Spanish CSIC, co-financed by the European Social Fund. IA was supported by a postdoctoral Fellowship from the FCT (SFRH/BPD/904 36/2012)., Peer reviewed