Ammonium transport and CitAMT1 expression are regulated by N in Citrus plants

作者：Camanes Gemma; Cerezo Miguel^*; Primo Millo Eduardo; Gojon Alain; Garcia Agustin Pilar

来源：Planta, 2009, 229(2): 331-342.

DOI：10.1007/s00425-008-0833-y

• Ammonium
• Ammonium transporter
• Citrus
• High-affinity transport system
• Low-affinity transport system

Citrus seedlings (Citrus sinensis L. Osbeck x Poncirus trifoliata Blanco) were used to describe the effects of different N treatments on the NH(4) (+) influx mediated by high- and low-affinity transport systems (HATS and LATS, respectively) and CitAMT1 gene expression. Results show that Citrus plants favor NH(4) (+) over NO(3) (-) influx mediated by HATS and LATS when both N sources are present in the nutrient solution and Citrus plants display a much higher capacity to take up NH(4) (+) than NO(3) (-). Furthermore, NH(4) (+) exerts a regulatory effect on NH(4) (+) HATS activity and CitAMT1 expression, both are down-regulated by high N status of the plant, but specifically stimulated by NH(4) (+) and the balance between these two opposite effects depends on the prior nutrition regime of the plant. On the other hand, supply of NO(3) (-) inhibits CitAMT1 expression but doesn't affect NH(4) (+) HATS activity on the roots. To explain this discrepancy, it is possible that other CitAMT1 transporters, up-regulated by N limitation, but not repressed by NO(3) (-) could be involved in the stimulation of NH(4) (+) HATS activity under pure NO(3) (-) nutrition or CitAMT1 transporter could be regulated at the post-transcriptional level.

• 出版日期2009-1