Protein Phosphatases in N Response and NUE in Crops

Nitrogen use efficiency (NUE) is an extremely important and challenging area of crop improvement to prevent economic wastage of fertilizers and also to minimize their adverse environmental consequences. Signaling proteins that mediate N response by regulating protein phosphorylation are emerging as useful targets in this regard. This chapter reviews the current understanding of the regulatory role of protein phosphatases in N response, NUE, and the possibilities ahead. Several protein kinases and phosphatases have been found to be involved in all aspects of N response, including uptake, metabolism, sensing, and signaling. Protein phosphatase 2C (PP2C) is involved in the regulation of nitrate transporter NRT1.1 and in the regulation of abscisic acid (ABA) signaling in nitrate sensing. Phosphatases also play regulatory role in photosynthesis and C-metabolism and may be involved in balancing carbon nitrogen cycle. Nitrate metabolism is regulated by phosphatase through target of rapamycin (TOR), and the fine-tuning of nitrate reductase activity through phosphatases is well known. In addition to these, it also explores the phosphatases identified for N response and NUE in different crops. Over all, this chapter provides a foundation in understanding the regulatory role of phosphatases in N response/NUE.