Leaf nitrogen remobilisation for plant development and grain filling

Abstract

A major challenge of modern agriculture is to reduce the excessive input of fertilisers and, at the same time, to improve grain quality without affecting yield. One way to achieve this goal is to improve plant nitrogen economy through manipulating nitrogen recycling, and especially nitrogen remobilisation, from senescing plant organs. In this review, the contribution of nitrogen remobilisation efficiency (NRE) to global nitrogen use efficiency (NUE), and tools dedicated to the determination of NRE are described. An overall examination of the physiological, metabolic and genetic aspects of nitrogen remobilisation is presented.

PvNAC1 and PvNAC2 Are Associated with Leaf Senescence and Nitrogen Use Efficiency in Switchgrass

“…These enzymes have been implicated in N-recycling during leaf senescence in the past [26]. Further, qRT-PCR confirmed the role of PvNAC1 in inducing expression of these genes (Fig.…”

“…GLN1.1 and GLN1.3 encode isoforms of cytosolic glutamine synthetase (GS1). GS1 has been implicated in nitrogen remobilization during leaf senescence [26]. For example, maize mutants lacking specific GS1 isoforms accumulated large amounts of amino acids and ammonia in leaves below ears due to a dysfunction in nitrogen export [28].…”

Moving micronutrients from the soil to the seeds: Genes and physiological processes from a biofortification perspective

“…These remobilized nutrients are most likely moved to developing seeds in annual crop species, providing that the senescence and seed import are synchronized to provide source-sink relationships. While it is well established that remobilized N is a major source of seed protein components for wheat and barley [15][16][17], data for other mineral elements is less abundant, although older studies demonstrated remobilization of Cu, Fe, and Zn in legumes [18,19] and wheat [20][21][22], and some newer studies have found similar results [23,24]. Remobilization of Fe and Zn increased when these micronutrients were withheld from the hydroponic solution post-anthesis, indicating that remobilization mechanisms might be upregulated under nutrient limitation [24].…”

Structural Changes in Senescing Oilseed Rape Leaves at Tissue and Subcellular Levels Monitored by Nuclear Magnetic Resonance Relaxometry through Water Status

“…Macromolecular degradation and the mechanism of reallocation of breakdown products are mediated by the up-regulation of senescence-related genes (Lee et al, 2001) in close relationship with both developmental and environmental conditions (Gombert et al, 2006). This leads to remobilization of carbon and nitrogen (N) compounds mostly from plastidial compartments (Martínez et al, 2008;Guiboileau et al, 2012), involving proteolytic activity in plasts, vacuole, and cytosol (Adam and Clarke, 2002;Otegui et al, 2005), chlorophyll breakdown (Hoertensteiner, 2006), galactolipid recycling (Kaup et al, 2002) in the plastoglobules (Brehelin et al, 2007), and loading of Suc and amino acids into the phloem through appropriate transporters (Wingler et al, 2004;Masclaux-Daubresse et al, 2008). In terms of leaf senescence at the cell level, where chloroplasts are degraded sequentially, relative organelle volume does not seem to be greatly modified, the vacuole remains intact, and in darkness-induced senescence the number of chloroplasts per cell decreases only slightly (Keech et al, 2007).…”