Physiological, Agronomical, and Proteomic Studies Reveal Crucial Players in Rice Nitrogen Use Efficiency under Low Nitrogen Supply

Abstract

Excessive use of nitrogenous fertilizers to enhance rice productivity has become a significant source of nitrogen (N) pollution and reduced sustainable agriculture. However, little information about the physiology of different growth stages, agronomic traits, and associated genetic bases of N use efficiency (NUE) are available at low-N supply. Two rice (Oryza sativa L.) cultivars were grown with optimum N (120 kg ha−1) and low N (60 kg ha−1) supply. Six growth stages were analyzed to measure the growth and physiological traits, as well as the differential proteomic profiles, of the rice cultivars. Cultivar Panvel outclassed Nagina 22 at low-N supply and exhibited improved growth and physiology at most of the growth stages and agronomic efficiency due to higher N uptake and utilization at low-N supply. On average, photosynthetic rate, chlorophyll content, plant biomass, leaf N content, and grain yield were decreased in cultivar Nagina 22 than Panvel was 8%, 11%, 21%, 19%, and 22%, respectively, under low-N supply. Furthermore, proteome analyses revealed that many proteins were upregulated and downregulated at the different growth stages under low-N supply. These proteins are associated with N and carbon metabolism and other physiological processes. This supports the genotypic differences in photosynthesis, N assimilation, energy stabilization, and rice-protein yield. Our study suggests that enhancing NUE at low-N supply demands distinct modifications in N metabolism and physiological assimilation. The NUE may be regulated by key identified differentially expressed proteins. These proteins might be the targets for improving crop NUE at low-N supply.

Establishment of a Comprehensive Evaluation System for Low Nitrogen and Screening of Nitrogen-Efficient Germplasm in Peanut

“…In the present study, 10 N-efficient and 10 N-inefficient genotypes screened at the seedling stage were assessed for N adaptation in the field under normal N (N90) and low-N (N0) conditions. N-efficient genotypes with high productivity can effectively relieve environmental stress and achieve nitrogen reduction, which has practical implications [28], so more desirable N-efficient genotypes are supposed to be both highly N-efficient and highly productive [21]. Peanut yield differed significantly among the genotypes [29], which was indirectly influenced by the number of pods and full pods per plant, 100 pod weight, and 100 kernel weight.…”

Role of Melatonin and Nitrogen Metabolism in Plants: Implications under Nitrogen-Excess or Nitrogen-Low

“…Additionally, nitrogen inhibitors, the split application of nitrogen, irrigation time, and the correct placement method of fertilizer which takes into consideration soil and crop type could improve NUE [ 93 , 94 , 95 , 96 ]. Therefore, melatonin must be studied more widely in the agronomic field in order to be considered a possible input into the NUE strategy [ 12 , 16 , 97 ], including the effects of enhancement by melatonin in the assimilation and metabolization of nitrogen, especially in symbiotic plants [ 54 , 55 ]. It is also important to study the effect of melatonin on rhizosphere and its microbiome, on which there are already some promising data [ 87 , 88 , 89 , 98 , 99 ].…”

“…Therefore, overuse of nitrogen can result in decreased crop productivity. Therefore, producing more whilst using less nitrogen, the so-called Nitrogen Use Efficiency (NUE), is a recommended practice [ 10 , 11 , 12 ]. Currently, the use of “smart fertilizers”, such as coated fertilizers, and the application of plant-growth-promoting rhizobacteria (PGPR) to the soil has ostensibly improved the nutrition of nitrogen in plants [ 13 , 14 , 15 ].…”

Low nitrogen stress-induced transcriptome changes revealed the molecular response and tolerance characteristics in maintaining the C/N balance of sugar beet (Beta vulgaris L.)

“…Some of these genes have been proven to be of general importance for photosynthesis and plant growth, including PSII dissolved oxygen enhancing proteins, cytochrome b6/f complex proteins, PSI subunits, FNRs, and Rubisco (Ermakova et al, 2019;Meng et al, 2021), which is consistent with our hypothesis that the identified DEGs in sugar beet played key roles in nitrogen use efficiency (NUE) under low nitrogen conditions. Many studies have reported that low nitrogen stress affects photosynthesis by affecting light and dark reactions in chloroplasts (Sultana et al, 2020;Tantray et al, 2022). Excited energy captured by the LHC is transferred to the core antenna complex and ultimately used in PSI and PSII reaction centers (RCs) for photochemical reactions.…”

“…Under stress conditions, different levels of regulation exist in cells to maintain a properly balanced metabolic ratio between carbon and nitrogen, which is necessary to avoid metabolic inefficiencies (Zhang et al, 2018a). In plants, photosynthesis is the energy source for carbon and nitrogen metabolism, and nitrogen deficiency has been reported to significantly reduce the photosynthetic capacity of plants (Tantray et al, 2022). Low nitrogen significantly attenuated the expression of genes controlling nitrogen metabolism (Figure 8, Supplementary Table 6).…”