Nitrogen and Stress

Abstract

Nitrogen is an essential macronutrient for the plants and fertilizer N-use effi ciency is becoming an increasing economic and environmental concern. The nutrient stress conditions of N defi ciency and N excess may get exacerbated by other abiotic stresses, which in turn are likely to be worsened by climate change. Exploring their interrelationships is being increasingly facilitated by the growing knowledge of the genome-wide N response as well as other abiotic stress responses in model plants. Nitrate and its more reduced forms are not only sources of plant N nutrition but also signals that govern their own uptake; N, C, and redox metabolism; and hormonal and other organism-wide responses. The signaling mechanisms involved in N response or response to N stress or N-use effi ciency are currently far less well understood than those in other abiotic stresses. The purpose of this review is to provide an overview of the current state of knowledge on normal N response and response to N stress, as well as their interrelationships with other abiotic stresses. Nitrogen is an important macroelement for plant growth. However, plant can't use atmospheric nitrogen as such and depend on its availability in more reactive forms such as urea, nitrate, ammonium, amino acids, etc. Even legumes depend on symbiotic N-fi xing bacteria to convert N 2 into ammonium ions to meet their N requirements. Therefore, the term nitrogen (N) is used in this review to represent a broad range of reactive species of N compounds. In agricultural soils, N compounds and other nutrients have to be constantly replenished as fertilizers/manures to enable repetitive cropping. As N fertilizers are expensive, N-use effi ciency becomes an important determinant of crop productivity. Keywords

Nitrogen Metabolism in Adaptation of Photosynthesis to Water Stress in Rice Grown under Different Nitrogen Levels

“…The effects of water stress on leaf N status are erratic, with increase, decrease, or constant in different species ( Jangam and Raghuram, 2015 ). In this study, total leaf N content was not affected by water stress at all the three N levels; however, water stress induced alterations of some nitrogenous compounds (e.g., nitrate, protein, proline, and amino acid) in rice leaf were N level dependent.…”

Heterotrimeric G-protein α subunit (RGA1) regulates tiller development, yield, cell wall, nitrogen response and biotic stress in rice

“…The indispensible roles of reactive nitrogen (N) compounds as nutrients and signals to regulate developmental plasticity, productivity and stress responses are known [65][66][67] . But their role in the improvement of N use efficiency (NUE) for sustainable agriculture is unknown, as how N-response translates into NUE is still not well understood [68][69][70] .…”

Transcriptomic and network analyses reveal distinct nitrate responses in light and dark in rice leaves (Oryza sativa Indica var. Panvel1)

“…This suggests faster turnover of metabolic processes by light-activated degradation pathways, thus offering new targets to regulate nitrate signaling in the context of damage and repair processes in plants. The stress-associated genes among the down-regulated DEGs common to light and dark conditions suggest crosstalk between nitrate and stress, an underexplored area of immense agronomic importance 26,68 .…”

“…Similarly, both networks revealed DEGs involved in stress response, such as the universal stress protein domain containing protein and MYB family transcription factor, among others. Such crosstalk between nitrate and stress signaling needs further characterization in view of its immense agronomic importance 26,68 .…”

“…The results were broadly similar to those from GO analysis, with nitrate-responsive changes to metabolism, cellular responses, regulation and hormone biosynthesis among others (Tables S4, S5). Further, a number of DEGs were found to be involved in development, biotic and abiotic stresses, suggesting signaling crosstalk between nitrate and stress responses in plants 26 . PageMan analysis revealed the over-and under-representation of different pathways affected by nitrate in light and dark conditions.…”