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Enhancing nutrient utilization pathways

Enhancing nutrient utilization pathways

Geomicrobiol J 34 pathhways — Metabolism boosters A, Beck M, Malmstrom J, Lam Nutriejt, Claassen M, et al. Varma, S. This is especially true if the interventions do no harm to health or care practices and support integrated and multisectoral programming.

Enhancing nutrient utilization pathways -

These forms are dynamic, and many transformations and reactions occur which convert particulate to dissolved forms and vice versa , and organic to inorganic forms. Only dissolved organic and inorganic forms can be taken up by microbes and primary producers directly. Microbes lower left e.

They can obtain these nutrients directly from dissolved organic and inorganic forms and indirectly from plant-based detritus and exudates. Increased nutrients can stimulate increases in microbial biomass and production, which can directly affect biota via increased microbial infection of invertebrates and fish.

Microbial increases also can increase organic matter quality and decomposition. Improved organic matter quality may benefit organisms that feed upon it like shredders , but shifts from coarse to fine particulate organic matter may benefit organisms which feed upon smaller particles e.

Increased microbial production also may reduce dissolved oxygen concentrations due to increased heterotrophic respiration and decomposition. Perhaps the most evident and common effect of increasing nutrient levels in streams is an increase in primary producer biomass or production.

When more nutrients are present, more periphyton, macrophytes and phytoplankton can grow center of diagram , assuming light levels are adequate. This increase in plant material can influence other organisms via several pathways. First, plant photosynthesis and respiration both may increase.

Enhanced photosynthesis can lead to supersaturated dissolved oxygen concentrations, which can cause gas bubble disease and adversely affect biota especially fish. In contrast, increased respiration by plants will consume oxygen, and may drive dissolved oxygen concentrations below critical levels, especially at times when photosynthesis is limited.

Ultimately, decreases in dissolved oxygen concentrations may lead to loss of taxa intolerant of low dissolved oxygen levels and increases in tolerant species. For N, increased photosynthesis may have an added adverse affect. Photosynthesis leads to an increase in pH, which may increase the amount of ammonium hydroxide present in streams.

This compound can be extremely toxic to aquatic organisms, especially fish. Increases in primary producers can directly affect both food quantity and food quality.

Most obviously, increased plant production can mean increased food for herbivores and detritivores. However, plant responses to nutrient enrichment often are taxon-specific. Based on the total and relative amounts of N and P present, certain plant taxa may increase while others decrease, leading to changes in plant assemblage structure lower right.

Thus, increases in plant production do not necessarily translate to increases in food availability. In the P diagram, for example, when excess P is supplied, the N:P ratio decreases.

As a result, algae taxa capable of fixing N 2 gas may be favored, as they have a source of N not readily available to other taxa. Many of these taxa may be less palatable or inedible. Filamentous algae may become more dominant with nutrient enrichment, and more prostrate forms may be shaded out.

These shifts can lead to a decrease in overall algal richness or evenness, and ultimately may affect herbivore assemblages. Changes in plant assemblage structure also can affect habitat structure, for example by changing the availability of refugia or the trapping of fine organic matter particles.

In larger streams and rivers with significant phytoplankton communities, phytoplankton blooms lower right may have adverse consequences for biota. For example, increases in suspended organic matter can increase turbidity, which may reduce light penetration and benthic plant abundance.

Turbidity increases also may lead to decreased visibility and potentially cause problems for visual predators. However, filtering organisms may benefit from increases in suspended organic matter.

Each of these pathways ultimately may contribute to biological impairment of stream biota. Total invertebrate richness or evenness may decline or specific taxa may be lost, and changes in any one population may indirectly affect other taxa. Skip to main content.

CADDIS Volume 2. Contact Us. Overview When to List Ways to Measure Conceptual Diagrams References. Overview Checklist of Sources, Site Evidence and Biological Effects Consider Listing Nutrients as a Candidate Cause Consider Commonly Associated Candidate Causes Nutrients are elements that are essential for plant growth.

Increased primary production and changes in species composition can be proximate causes of effects on macroinvertebrates and fish. These effects may result from:. These characteristics, in turn, may be proximate stressors for the aquatic community.

Consider commonly associated candidate causes when listing nutrients as a candidate cause:. When to List Sources and Activities that Suggest Listing Nutrients as a Candidate Cause Site Evidence that Suggests Listing Nutrients as a Candidate Cause Biological Effects that Suggest Listing Nutrients as a Candidate Cause Site Evidence that Supports Excluding Nutrients as a Candidate Cause Sources and Activities that Suggest Listing a Nutrient-Related Candidate Cause Nutrient discharges from point sources enter waterbodies from discrete locations e.

Ways to Measure Nitrogen Common forms of nitrogen in aquatic ecosystems include gaseous nitrogen N 2 ; ammonia NH 3 from nitrogen fixation, fertilizers, animal wastes and organic matter decomposition; nitrite NO 2 - and nitrate NO 3 - from nitrification or fertilizers; and organic nitrogen compounds [see Wetzel , Chapter 12 for discussion of the nitrogen cycle].

Table 3. Nitrate and nitrite may also be analyzed via ion chromatography [Standard Methods B APHA et al.

Phosphorus Phosphorus is present as dissolved orthophosphate PO 4 3- , various organic phosphorus compounds and sediment-associated particulate phosphorus [see Wetzel , Chapter 13 for discussion of the phosphorus cycle].

Table 4. Digestion methods for TDP and TP are outlined in Standard Methods P B APHA et al. More about Conceptual Diagrams Simple Conceptual Model Diagram Nitrogen and Phosphorus Enrichment of aquatic systems due to excess nutrient concentrations is a common cause of biological impairment.

Simple and Detailed Conceptual Model Diagrams: N and P Simple Conceptual Diagram: N and P PPT 1 pg, K Detailed Conceptual Diagram: N and P PPT 2 pp, K. References APHA American Public Health Association , AWWA American Water Works Association , WEF Water Environment Federation Standard Methods for the Examination of Water and Wastewater 20th edition.

American Public Health Association, Washington DC. ASTM Annual Book of ASTM Standards. American Society for Testing and Materials, Philadelphia PA.

Barbour MT, Gerritsen J, Griffith GE, Frydenborg R, McCarron E, White JS, Bastian ML A framework for biological criteria for Florida streams using benthic macroinvertebrates.

Journal of the North American Benthological Society Barbour MT, Gerritsen J, Snyder BD, Stribling JB Rapid bioassessment protocols for use in wadeable streams and rivers: periphyton, benthic macroinvertebrates, and fish 2nd edition.

Environmental Protection Agency, Office of Water, Washington DC. EPA B Carlson RE, Simpson J A Coordinator's Guide to Volunteer Lake Monitoring Methods. North American Lake Management Society. Clarke KR, Warwick RM Change in Marine Communities: An Approach to Statistical Analysis and Interpretation.

Plymouth Marine Laboratory, National Research Council. Deshon JE Development and application of the Invertebrate Community Index ICI. Biological Criteria and Assessment: Tools for Risk-Based Planning and Decision Making. Lewis Publishers, Boca Raton FL. Dodds WK, Welch EB Establishing nutrient criteria in streams.

Journal of the North American Benthological Society 19 1 Griffith MB, Hill BH, McCormick FH, Kaufmann PR, Herlihy AT, Selle AR Comparative application of indices of biotic integrity based on periphyton, macroinvertebrates, and fish to southern Rocky Mountain streams.

Ecological Indicators Klemm DJ, Blocksom KA, Fulk FA, Herlihy AT, Hughes RM, Kaufmann PR, Peck DV, Stoddard JL, Thoeny WT, Griffith MB, Davis WS Development and evaluation of a macroinvertebrate biotic integrity index MBII for regionally assessing Mid-Atlantic Highlands streams.

Environmental Management Legendre P, Legendre L Numerical Ecology 2nd English edition. Elsevier, Amsterdam, Netherlands. McCune B, Grace JB, Urban DL Analysis of Ecological Communities.

MjM Software Design, Gleneden Beach OR. Miltner RJ, Rankin ET Primary nutrients and the biotic integrity of rivers and streams. Freshwater Biology National Research Council Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution.

National Academy Press, Washington DC. USGS The Quality of Our Nation's Waters: Nutrients and Pesticides. Geological Survey. Circular van Dam H, Mertens A, Sindeldam J A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands.

Netherlands Journal of Aquatic Ecology Weitzel RL Ed. ASTM STP Wetzel RG Limnology 3rd edition. Academic Press, San Diego CA. CADDIS Home Vol 1. Stressor Identification Vol 2.

Sources, Stressors and Responses About Sources About Stressors Ammonia Dissolved Oxygen Flow Alteration Herbicides Insecticides Ionic Strength Metals Nutrients pH Physical Habitat Sediments Temperature Unspecified Toxic Chemicals About Responses Vol 3. During this process, key enzymes including nitrate reductase NR , nitrite reductase NiR , glutamine synthetase GS , glutamate dehydrogenase GDH , glutamine synthase GOGAT , asparagine synthetase AS , and aspartate aminotransferase AspAT , are used to make the N available to the plants in the form of amino acids Xu and Zhou, These enzymes were assessed in citrus to determine biochemical markers of N status Singh et al.

The conversion of input N as a raw material to final product amino acids is mediated by a series of enzymes. Furthermore, in plastids, 2 moles of ferredoxin are used by GOGAT to convert Gln into an organic acid, 2 oxoglutarate 2-OG Crawford, As a result of the transfer of Glu into organic acids, several amino acids AA are produced via transaminases.

Figure 3. Nitrogen transporters and key enzymes involved in N metabolism and acquisition in plants. Panel A represents the activity in leaves. Panel B represents the activity in plant. Panel C represents the activity within the roots.

Previously, cotton was an orphan crop; many studies have been conducted to increase the NUE by focusing on the N concentrations and morphological and biochemical traits, but not much has been done on N metabolism and related enzymes, such as NR, NiR, GS, GOGAT, and GDH, which carry out the whole process from N uptake to use Abenavoli et al.

Furthermore, N-containing compounds, such as amino acids and proteins, are key partners of N metabolism processes, including assimilation and metabolism, which determine genotypic responses to N supply Quan et al. Therefore, these enzymes and N metabolism are considered the most vital biochemical factors for improving NUE in cotton Xu et al.

Another study was conducted to determine the contrasting NUE of six cotton genotypes. Biochemical and morpho-physiological traits such as N metabolic enzymes, shoot dry weight, and root traits were mostly affected in response to varying nitrate concentrations.

NUE positively correlated with improved N uptake efficiency Iqbal et al. In another study on cotton Iqbal et al. Because it is challenging to improve NUE by lowering N supply and selecting N efficient cotton genotypes, uptake, utilization, and remobilization of available N.

Based on a contrasting N metabolic study, N uptake efficiency NUpE , and N utilization efficiency NUtE , CCRI and XLZ showed efficient NUE Iqbal et al. The N concentration and N-metabolizing enzymes were attributed as important traits that confer high NUpE.

After applying higher N concentrations, shoot and root NR, GOGAT, and GDH enzyme activities increased. However, different genotypes exhibited contrasting behaviors Iqbal et al.

However, according to recent literature Fan et al. NPF and NRT2 families are mainly responsible for low-affinity transport systems LATS and high-affinity transport systems HATS , respectively Williams and Miller, ; Tsay et al.

The NRT1 NPF nitrate transporters in other crops and transporters that behave differentially based on the varying nitrate concentration has been discussed in detail Segonzac et al. Figure 4. Roles of different nitrogen transporters in nitrate uptake and efflux from the soil, transportation from roots to shoots, allocation and assimilation in plant leaves, and seed development.

As mentioned in the above section, these nitrogen transporters are linked to different families. In plants, multiple nitrate transporters Table 1 perform NO 3 — uptake. Both NRT1 NPF and NRT2 transporter families affect plant growth and seed development because of the differences in NO 3 — uptake efficiency Wang et al.

NRT1 NPF was identified in Arabidopsis Tsay et al. The NPF family includes 53 genes in Arabidopsis, were identified in higher plants, and 93 genes in rice. These are further subdivided into 8—10 families as reviewed by Iqbal et al. In the NRT1 NPF family, Arabidopsis includes 53 genes, of which 51 show differential expression patterns in the whole plant Tsay et al.

The NRT1 NPF family functions as NO 3 — transporters and a diverse range of substrates, including abscisic acid, nitrite, amino acids, peptides, chloride, glucosinolates, gibberellins, auxin, and jasmonoyl-isoleucine Krouk et al.

Table 1. Various nitrogen transporters involved in different functions of nitrate uptake, utilization, and remobilization. Eight NRT2 transporters that respond to HATS have been identified in different plants Von Wittgenstein et al.

Although not many nitrate transporters have been identified in, we present the transporters from other plants such as Arabidopsis and rice. In Arabidopsis, several NRT2 transporters have been identified; four of them, including NRT2.

However, NRT2. Although NRT2. However, compared to NRT2. Moreover, NRT2. Overall, NO 3 — acquisition depends on the specificity of NO 3 — transporters because NRT2. In response to long-term starvation, NRT2.

In addition, NAR2 NRT3 from the NRT3 family is another transporter that develops a coupling relationship with NRT2 to transporters to NO 3 — in plants Li et al.

Many NRT2 transporters have been identified and studied in other plants, including Chlamydomonas reinhardtii Zhou et al.

These NRT transporters can be manipulated to improve NUE. However, the overexpression of genes responsible for ammonium transporters has not yet been successful Meister et al. In addition to inorganic N acquisition, plants absorb organic nitrate in amino acids AA Näsholm et al.

Various root transporters, including AAP1 and AAP5, proline transporter ProT2, and lysine-histidine-type transporters LHT1 and LHT6, are responsible for the uptake of amino acids The et al.

However, this is only possible in fields that rely on manure or compost Enggrob et al. Upon assimilation, it is converted into AA Meyer and Stitt, Different NO 3 — transporters have been shown to increase N assimilation in plants.

In Arabidopsis, NPF7. Besides these, many other genes are also responsible for the better uptake, assimilation, and remobilization of NO 3 — from roots to shoots Fan et al. According to the cited literature Fang et al.

However, it is yet to be determined whether overexpression of these NRT2 transporters in roots is sufficient to improve NUE. In the latest research on Arabidopsis, rice, and tobacco, overexpression of the hyperactive chimeric NO 3 — transporter AtNC4N in the phloem of old leaves increased N uptake and improved NUE under low N levels.

Another study showed that the OsNRT1. Many other N transporters, such as NRT1. Furthermore, several other genes in different plants have been shown to improve plant growth and NUE, including the nitrate transporter OsNPF4.

How the nitrate signaling and gene expression networks can be used to improve NUE in plants are not yet completely understood. Additionally, researchers have attempted to increase NUE by modulating the expression of key genes involved in NO 3 — uptake, assimilation, and remobilization in various plants.

However, no significant success has been recorded McAllister et al. Thus, success cannot be achieved until all other processes, including uptake, transport, assimilation, and remobilization, are understood. To improve NUE, it is also necessary to understand these processes and how they coordinate the expression of genes involved in the NO 3 — response.

NO 3 — induces a primary NO 3 — response that regulates the transcriptional response without requiring de novo protein synthesis Gowri et al.

As a result of this rapid response, gene expression can be induced within minutes, reaching a peak at approximately 30 min. However, NO 3 — concentration determines the induction levels of PNR genes Hu et al. Various PNR gene families have been studied in plants, such as NRT1 NPF , NRT2, NIR, NIA1, NIA2, and other genes responsible for different metabolic processes, including the trehaloseP metabolism pentose phosphate pathway and glycolysis Scheible et al.

Several main NO 3 — signaling pathways, including transcription factors, peptides and proteins, kinases, NO 3 — transporters, and calcium signaling. Because cotton has not been well studied regarding NO 3 — molecular signaling pathways, we focused on these pathways in other crops to understand the potential mechanism in cotton.

Two NO 3 — transporters, NRT1. In the case of short-term and long-term NO 3 — supply, NRT1. Based on its dual-affinity property, it can switch between high- and low-level NO 3 — responses Hu et al. Except for PNR regulation, NRT1. At high NO 3 — concentrations, NRT1.

While At low NO 3 — concentrations, NRT1. An additional NO 3 — sensing system is also present, as the abolishment of NRT1. After NO 3 — sensing by NRT1. Calcium and various transcription factors are the main role players in signal transduction.

Three CIPKs CPK10, CPK30, and CPK32 and their partner CBL indicated that calcium also functions in NO 3 — signaling Krouk, Calcium acts as a secondary messenger in the NO 3 — signaling pathway Liu et al. The first time, this study was conducted 30 years ago on barley and maize, where it showed that NO 3 — responsive genes show varying expression as a result of EGTA or LaCl3 pretreatment Sakakibara et al.

Furthermore, its function as a NO 3 — signaling pathway has been investigated in various studies Riveras et al. Moreover, many other transcription factors TFs , like NLP7, TCP20, LBD37, LBD38, LBD39, CIPK8, SLP9, TGA1, TGA4, CIPK23, bZIP1, BT1, and BT2 have been identified that interact with nitrate responsive genes, carry out the function of NO 3 — response, and improve NUE Wang Y.

Based on recent bioinformatics analyses, BT1 and BT2 have proven to be great assets for improving NUE. BT1 was identified as the closest homolog of BT2. BT1 and BT2 improve NUE by repressing the expression of the nitrate transporters NRT2.

Both TFs are involved in plant growth. However, it is yet to be determined whether BT1 and BT2 target multiple genes under N-sufficient and N-deficient conditions. The RWP-PK TFs family includes NLP7 TF.

In a genome-wide analysis, NLP7 was identified as a player in modulating the expression of various genes involved in NO 3 — signaling, uptake, and assimilation Marchive et al. Similarly, SPLN also regulates the expression of different NO 3 — transporter genes, including NPF6.

Generally, N is recycled and remobilized in source leaves after uptake by the roots. It is delivered to the sinks via the phloem as amino acids, NO 3 — , and ureides Figure 5 Tegeder and Masclaux-Daubresse, However, different agronomic characteristics, such as NUE, grain filling, and yield, depend on better N remobilization in the source and its allocation to sink organs.

The removal of N is initiated mainly during leaf senescence The et al. In plants, senescence is a developmental process that regulates the nutrient requirements. In addition to the natural aging process, many other factors, such as nutritional starvation, pathogen infections, C-N ratio, photosynthetic activity, photoperiod, C accumulation, and various other cues, can initiate senescence.

The limited availability of N also increases leaf senescence earlier than the sufficient availability in sunflowers Bieker and Zentgraf, Figure 5.

Illustrates the mechanism of nitrogen remobilization from source leaf to sink seed. Various known and unknown transporters are involved in portioning, as mentioned in Tegeder and Masclaux-Daubresse AA, amino acids. In addition to N, some environmental factors, such as light quality and quantity and reactive oxygen species ROS Zimmermann et al.

Different sink organs and developmental processes require N. During anthesis, it varies according to the genotype. Varying concentrations of N are responsible for the differential uptake of N among different Arabidopsis accessions.

Upon application of High N concentrations, most of the N is remobilized to the seeds, whereas at low N concentrations, it is allocated to rosette leaves Masclaux-Daubresse and Chardon, Here, we will focus on natural-induced senescence accompanied by the movement of nitrogenous nutrients from source leaves to sink organs and various efforts to increase NUE in response to the source and sink relationship.

Generally, due to autophagy, proteins, organelles, and cytosolic macromolecules are degraded during leaf senescence, and N is translocated toward sink organs Chen et al. Associated cytoplasmic components are dismantled and degraded during autophagy, which plays an important role in regulating and remobilizing nutrients from source to sink organs Tegeder and Masclaux-Daubresse, ATGs genes are responsible for this autophagy process during leaf senescence, and are upregulated during autophagy Chung et al.

This is further reinforced by the fact that leaf senescence is initially observed because of chloroplast dismantling and degradation.

According to the cited literature Martínez et al. Details regarding protein degradation mechanisms are provided by various studies Tegeder and Masclaux-Daubresse, ; Gill et al.

Seeds are the major sink organs during N remobilization, which depends on different factors: strength of the seed sink, translocation processes in leaves, stems, and reproductive organs, and efficiency of phloem pathways Manghwar et al.

Based on acquired knowledge in different plants, it is well known that asparagine and glutamine are the major translocated amino acids from source to sink organs. Their concentrations also increased during leaf senescence. The amino acid permease AAP family is a candidate gene for improving the phloem loading efficiency.

Different genes, including AAP4, AAP5, BnAAP1 , and BnAAP2 , have been implicated in phloem loading Fischer et al. During leaf senescence, N remobilization and assimilation can improve the NUE of plants.

Both GS1 and GS2 proved influential in improving NUE. Further improvement of N remobilization depends on the severity and severity of leaf senescence activity Diaz et al. There is a long list of protease genes responsible for protein degradation and N remobilization. Among these genes, SAG12 is a widely studied enzyme that catalyzes the cysteine protein in leaves.

In addition, its homologs are also present in other crops and are responsible for N remobilization and improvement of NUE in oilseed and tobacco Chung et al.

Furthermore, glutamate dehydrogenase GDH is also important for improving NUE, as it functions to remobilize N Lea and Miflin, However, overexpression of GDH did not result in N remobilization as in the case of tomato Slgdh-NAD: B1 in tobacco, GDH from Sclerotinia sclerotiorum and Magnaporthe grisea in rice Purnell et al.

In contrast it improved NUE in other plants, such as overexpression of EcgdhA from Escherichia coli in tobacco and maize Ameziane et al. In addition, overexpression of AngdhA from Aspergillus nidulans in potato Egami et al.

Autophagy respondent genes such as AtATG8 in Arabidopsis, OsATG8b, OsATG8a, and OsATG8c in rice also proved valuable in improving NUE under sufficient conditions of N supply Gallais et al. Other factors, such as N remobilization in the form of inorganic or ionic N, or combined with organic molecules, also play a differential role in improving NUE.

Different studies have reinforced the significant role of inorganic N in N remobilization toward sink organs, but it also depends on the availability of sufficient N inputs Masclaux-Daubresse et al.

Various studies on NO 3 — transporters, including NRT2. Another study was conducted on the NO 3 — transporter NRT1. They manipulated its remobilization, which improved NUE and increased plant growth, as it was involved in the meditation of stored NO 3 — from the source to sink organs Chen et al.

In addition to molecular-level studies, some common agronomic practices are also essential for better source-to-sink relationships in plants. Research on efficient and inefficient cotton genotypes, CCRI and XLZ, showed that moderate to high N applications improve the remobilization of the source-to-sink relationship, which ultimately increases the NUE and yield Iqbal et al.

Furthermore, different foliar applications also proved beneficial. Under treatment with different N foliar applications, such as NO 3 — and urea, winter wheat plants showed increased grain filling and source-to-sink relationships of N remobilization, as Lyu et al.

However, many N studies have been conducted on plants other than cotton plants. Currently, there is a dire need to study cotton plants to improve the NUE and source-to-sink relationship for better remobilization of N by employing molecular and agronomic studies. Crop plants largely absorb N in the form of nitrate NO 3 — Robinson et al.

Unlike ammonium, a large concentration of nitrate ions are assimilated in plant tissues and then translocated to plant shoots for assimilation. It is well established that N rates and sources significantly affect plant growth and developmental process Irshad et al.

Therefore, selecting the appropriate rate and method based on plant species, growth stage, soil, and environmental conditions is necessary to maximize plant growth and NUE Marschner, ; Niu et al.

Other farm management practices, including genotype selection, also significantly improved NUE. Genotype development and screening have been reported to be imperative for improving the uptake and utilization of N Iqbal et al.

In a recent study, Iqbal et al. They reported increased N uptake and utilization efficiency, better plant growth, chlorophyll content, and gas exchange in the N-efficient genotype when supplied with nitrate-N Iqbal et al. Improved root traits in nitrate-fed plants, including length, dry weight, and surface area, have been reported previously Schortemeyer and Feil, Another study also reported better seedling growth in cotton when fed nitrate N than ammonium-fed seedlings, mainly due to better photosynthesis under increased translocation of nitrate to the photosynthesis system Irshad et al.

Ammonium application is also not recommended, as it reduces the uptake of potassium and cations to retard stomatal function and inhibit osmotic regulation, respectively Lopes and Araus, Similarly, low NUE in cotton under ammonium application has also been attributed to inhibited ammonium metabolism and reduced protein synthesis Pessarakli and Tucker, Chen et al.

They reported that a moderate N application rate kg ha —1 significantly increased seedling growth and cotton yield, thereby promoting NUE Chen et al. Similarly, in a recent study, Wang et al. Nitrogen application rate, time of application, the N source, and other agronomic practices affect crop yield, N uptake, and its movement and metabolism within the plant, depending on the plant species Ali, ; Ali et al.

Xu et al. Similarly, Yao et al. Recently, Liu et al. N at kg ha —1 was applied at the flowering stage, promoting N utilization and efficiency in cotton grown under a wheat-cotton double cropping system Liu et al.

In another study, Du et al. Wei et al. They reported that a moderate N application rate with drip irrigation promoted N uptake, translocation, and efficiency in cotton grown in arid regions Wei et al. N application at kg ha —1 and straw incorporation significantly improved N uptake and NUE, as reported by Wang et al.

Niu et al. They reported that CRI 69 and ZZM , as N-inefficient cultivars, had increased N uptake and translocation into different parts and ultimately NUE in cotton Niu et al.

Plants inoculated with Azospirillum brasilense also show better N uptake, translocation into different tissues, and NUE Saubidet et al. Plants have evolved various mechanisms involving enzymes and activating genes to increase NUE Table 2. However, only a few studies have discussed the key enzymes and genes directly or indirectly involved in enhancing NUE in cotton Iqbal et al.

NUE highly depends on N uptake, utilization efficiency, and N assimilation rate Garnett et al. The involvement of the N-assimilation enzyme glutamine synthetase in promoting NUE through increased N harvest index Brauer et al.

Cai et al. GS has been reported to enhance biomass production Chichkova et al. NR and NiR are important enzymes for N assimilation; their role in enhancing NUE has been well reported in terms of enhancing dry weights Abiko et al. The GDH NADH-GDH has been reported to play a role in assimilating inorganic N to form glutamate by combining ammonium with 2-oxoglutarate Fontaine et al.

It is also well documented that NADH-GDH facilitates ammonium assimilation, which has an advantage over glutamine synthetase. The plastidic isoenzyme GS2 is also involved in primary N assimilation, and the cytosolic GS isoenzyme GS1 is involved in the recycling of organic N Masclaux et al. According to Martin et al.

NADH-GOGAT, a pyridine nucleotide-dependent GOGAT isoenzyme, is present in bundle-sheath cells and is involved in glutamate synthesis to promote plant growth Tabuchi et al. The essential roles of another N-assimilation enzyme, alanine aminotransferase, in increasing biomass and seed yield have been well documented in previous reports Good et al.

According to Lam et al. Different breeding approaches have been used in recent years to select the most appropriate traits for improving NUE.

In plants, NUE is a complex trait that depends on the availability of soil N and various internal and external factors, including photosynthetic carbon fixation. NUE, the ratio of grain yield and N uptake, also varies with N application rates, where different genes are expressed in plants according to N rates Hirel et al.

According to Hirel et al. The GS gene gln4 has been reported as a housekeeping gene that controls NUE and influences yield by promoting ammonia assimilation Hirel et al. A previous study reported enhanced NUE and yield upon overexpression of Gln and Gln He et al.

In an investigation by Castaings et al. In a recent study, Cao et al. Table 3 lists the genes involved in NUE. The glutamine synthetase gene GS1 and nitrate transporter genes OsNRT2. Similarly, according to Zhao et al.

In another study, Shrawat et al. In addition, the ammonium transporter gene OsAMT1;1GS1 has been reported to have a higher seed yield, nitrogen use efficiency, and number of seeds Ranathunge et al. In plants, the GLN2 nuclear gene is involved in the assimilation and re-assimilation of ammonium produced by nitrate reduction and photorespiration Ranjan and Yadav, Similarly, according to Bernard and Habash , the GLN1 gene facilitates the recycling of ammonium during leaf senescence Bernard and Habash, The dual affinity transporter protein AtNRT1.

Similarly, Li et al. Improved NUE via increased biomass has been well reported as a result of gene expression, including GS1 Fuentes et al. Increasing crop production is largely associated with fertilizer use and application rates. The optimum supply of nutrients plays a significant role in increasing crop production and NUE Erisman et al.

In agricultural farming systems, N management should achieve higher crop productivity without polluting the environment Klerkx et al. In the form of nitrate, N is a mobile nutrient that severely impacts the environment through GHGs emissions Hristov et al.

Plants obtain N from different sources, including residual N, organic matter decomposition, and biological N fixation, and it is imperative to understand the contribution of these sources to enhance NUE Plett et al. Various approaches have been used in recent years to manage N and enhance the NUE.

Soil and plant-based analysis, based on SOM, yield goal, N credit from the previous crop, manure, and irrigation water, is among the most commonly used techniques for N management in different crops Dobermann and Cassman, According to a recent study by Guo et al.

Variables such as slopes, soil depth, and drainage within a landscape significantly affected seed yield. Higher N fertility status has been reported in foot slopes due to higher SOM content and flow of water, while it is also well established that soils with upper landscape positions are poor with SOM Sharma et al.

Compared to other nutrients, N is more prone to many soil transformations that occur within the soil, particularly above the soil layer, and can influence NUE Yadav et al. Significant N losses have been reported owing to leaching, soil runoff, and volatilization. Therefore, it is necessary to choose appropriate methods of N application to maximize N availability to crop plants and NUE Sharma et al.

The broadcasting method of N application is not recommended because it causes severe losses in crop yield, and N is applied through volatilization and immobilization Lasisi et al. Sensitive plants have been used for a long time as a marker of soil nutrient status.

Some crop species are good markers for overall growing conditions, as they are immediately correlated with climatic conditions and soil management techniques, as discussed recently by Sharma and Bali A positive correlation between chlorophyll content, corn yield, and N accumulation has been reported previously Han et al.

Breeding for improved NUE can be attained through an assortment of different components Cormier et al. However, omics-based studies offer results that enable us to focus on routes for improvement Cormier et al.

In addition, high-throughput phenotyping using high-throughput genotyping techniques will promote research on variable environments and species, which could significantly enhance their nutrients Banerjee et al.

This review critically assessed various agronomic and molecular approaches for quick and efficient NUE in cotton production. However, several concerns remain to be addressed. These could improve metabolic activities, the role of nitrogen transporters, signaling and sensing of metabolic pathways, and the relationship between sources and sinks.

Ultimately, we recognize that improving NUE in cotton will be equally beneficial for the environment and growers to maximize their profits. Understanding and following these motives will assist in building better education and other activities to eliminate barriers to nitrogen use efficiency in cotton farming.

MC, QA, LZ, and LS-L: conceptualization, visualization, and writing—original draft. LZ and LS-L: writing—review and editing, validation, conceptualization, supervision, and funding acquisition. MH, SH, MA, TJ, TM, MS, AU, WA, and SN: writing—review and editing.

All authors contributed to the article and approved the submitted version. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers.

Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher. Abenavoli, M. Phenotyping two tomato genotypes with different nitrogen use efficiency.

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Appropriate inputs to grow these diverse foods must also be available so local production can meet demand. Local supply and demand may also be influenced not only by market prices but also by SBC, nutrition knowledge, and social marketing, which may help drive consumer preferences.

At the same time, household investments in health, including potable water sources and toilets, preventive care, and other basic necessities, are crucial to supporting good nutrition, especially for women and young children. All rural farm households must balance their spending decisions between farm production and marketing investments and the immediate purchases of food, health, and care necessities.

The effect of income on nutrition is not direct or easily predictable; it is always modified by what is available, affordable, and convenient to purchase; who decides what is purchased; and the myriad factors that drive that decision. Women's empowerment incorporates multiple aspects, including the decision-making power related to income, time, labor, assets, and knowledge or preferences of female community members.

Increasing the agricultural income that women can control strengthens the income pathway to nutrition. Women's income enables expenditures on food and health care, affecting diet and health status. Research shows that in many places around the world, income controlled by women is more frequently used on food and health care for the family, particularly for children UNICEF ; Smith et al.

Often, the best way for women to influence how household income is spent is by earning their own income. For women in rural areas, an agriculture-related livelihood is the most common way a family makes a living. Women's decision-making also affects what is produced on the farm, and women's control of income and assets can affect productivity based on their spending decisions and on the social networks and cultural norms that influence those decisions Food and Agriculture Organization of the United Nations [FAO] Training female and male farmers in farm management and business skills can optimize the income earned with the available time, labor, assets, and capital.

a vital step in improving nutrition in a household with an agricultural livelihood requires that farming business decisions give attention to how women are involved Agricultural development interventions can strongly affect women's use of time as well as their labor burden.

Women are typically responsible for a wide range of household and agricultural tasks, including child and infant care and feeding and their own self-care. Activities that influence the amount of time or labor women spend on agriculture- related tasks can affect their own health and energy expenditure, and in turn their capacity to feed and care for infants, young children, and themselves.

For this reason, a vital step in improving nutrition in a household with an agricultural livelihood requires that farming business decisions give attention to how women are involved in agriculture activities. For example, if agriculture development activities strive to promote the production of various nutritious foods with high market value to help increase women's income, they must be designed and monitored to also ensure they are not contributing to women's time and labor burdens.

The pathways between agriculture and nutrition are influenced by several key contributors to the enabling environment, which are factors at the community, regional, or national level affecting the household-level pathways.

The enabling environment is shown as the shaded box behind the pathways in the figure above. Its key components include the food market environment; the natural resources environment; the health, water, and sanitation environment; and knowledge and norms.

It should be noted that agricultural interventions and policies can affect these components. The interaction between the various components of the enabling environment and the agriculture-to-nutrition pathways are described in the following section.

Feed the Future promotes inclusive agriculture sector growth that expands markets and trade for smallholder farmers. The food market environment affects the kinds of foods that are available and likely to be purchased, as well as those that are likely to be produced by farm households as a response to price signals and market incentives.

Farm households determine what gets sold in markets and what is consumed at home largely as a response to the food market environment. Both government policies and the actions of the private sector impact the availability and affordability of food in the market.

For example, open international trade policies may increase the availability in local markets of imported food and beverages that can significantly affect local diets.

By the same token, favorable tax policies may increase household access to nutrient-dense food products. Public and private investments in food value chains meanwhile determine the processing, storage, and marketing of food, affecting the quantity and quality including safety of food in the market.

Finally, agriculture and food systems contribute greatly to the food market environment in how nutrition messages are conveyed to consumers.

Labeling and social marketing, for example, are tools that have been used by the food marketing industry and other value chain actors to influence food purchase decisions and consumption habits. This type of marketing may influence what people eat more extensively than nutrition education.

Purchase decisions are affected not only by the relative price of different foods, but also factors such as convenience of purchase and preparation, available information about foods, and related perceptions of quality and safety. The last two factors in particular are influenced by marketing efforts of the private and public sectors.

The food environment therefore interacts with household decision-making and food purchases in many ways and has a significant influence on household and individual nutrition. All pathways between agriculture and nutrition are affected by natural resources: water, soil, climate, and biodiversity.

Natural resource endowment affects agricultural production potential and, therefore, management strategies for income generation and food availability.

Appropriate management of often scarce natural resources, such as sustainable harvesting, use and drainage of water, soil fertility management, and managing access to productive land, is critical to a successful farming business.

Rainfall patterns directly impact production cycles of farms without access to irrigation; and water availability, often a cause of human conflict, determines the type of viable farming systems.

Access to potable water is essential for human health and nutrition—for sustenance, food preparation, and hygiene and sanitation. Irrigation for agriculture can impact human health, especially in areas of intensive cultivation that use chemical inputs.

successful interventions along any of the pathways will require purposeful planning toward nutritional goals while mitigating ever-changing natural resource constraints.

Soil quality directly affects the quality and yield of crops, and maintaining its fertility over time is a primary consideration in farming as a source of food and income. Therefore, the appropriate management of scarce natural resources has direct consequences for the livelihoods of food insecure and nutritionally vulnerable families.

With changing climate patterns, the predictability of farm production cycles is also affected. These challenges require farmers to continually adapt their agricultural livelihood strategies to maintain the viability of crops and livestock.

Therefore, successful interventions along any of the pathways will require purposeful planning toward nutritional goals while mitigating ever-changing natural resource constraints.

Nutritional status is strongly influenced by the health, water, and sanitation environment and access to health services. Agricultural production interacts with the health, water, and sanitation environment.

For example, some agricultural practices may contaminate water available for household use e. Infants and young children may be at risk of illness when livestock or agricultural production diminishes household sanitary conditions. With compromised systems, children are unable to properly absorb the nutrients they are consuming, thus negating any potential positive nutrition outcomes from increases in agriculture production or income.

A key component of nutrition-sensitive agriculture therefore includes consideration of the activities' potential effects on the health, water, and sanitation environment. Illness and poor health, whether resulting from agricultural practices or not, may affect household agricultural productivity as a whole.

For example, in households or communities experiencing chronic or seasonal illness, food production and income generation are compromised by a lack of labor. The knowledge held by key family and community members has a major bearing on the decisions made within households related to agriculture and nutrition.

For example, Feed the Future activities that promote knowledge of nutrition and health may affect decisions around food production, purchase, and consumption to enhance positive outcomes for both the agriculture and nutrition sectors while avoiding negative impacts.

An example of this can be seen in activities that promote farm management and business planning skills, as these have proven to be essential for successful farmers.

Business planning should take household expense and cash flow needs, both planned and unplanned, into account. Including costs for the purchase of a healthy diet, antenatal care, or unforeseen illness as a part of a smallholder's business plan is not only beneficial to the family's livelihood but also to its nutrition, health, and well-being.

Decisions that result in improved market access and income for farm households require knowledge and skills in production, storage, processing, selling, and marketing, to name a few of the many areas in which farmers are expected to be "experts.

For example, nutrition-sensitive livestock-raising practices may change how animals are kept in relation or proximity to the home, or nutrition-sensitive irrigation practices may affect how water is managed for agriculture to avoid household consumption of contaminated water.

SBC activities promoting nutritious diets and healthy practices— whether provided within an extension system or as part of a collaboration with other sectors—can further enhance the impact of agriculture activities on nutrition.

The current global consensus of Key Recommendations for Improving Nutrition through Agriculture reflects the agriculture-nutrition pathways identified in this brief. The United States Agency for International Development contributed to the identification and sharpening of these recommendations within a broad consultation process 2 that included discussions and country presentations at regional Agriculture and Nutrition Global Learning and Evidence Exchange workshops.

This collaborative process yielded a consensus list of 10 key principles for programming and five principles for policy above right and in full in Annex 3.

The pathways framework is envisioned as a conceptual tool for activity planners to explore ways in which interventions may impact human nutrition. The framework outlines key theoretical steps needed to reach outcomes on dietary consumption or women's income or to have an impact on nutritional status.

While these pathways are not linear, and the interactions in some contexts are quite complex, the framework can be a useful tool in activity design.

It is also useful for making decisions about how best to measure the success of an approach on its intended outcomes. The key principles can be used as a broad checklist in the design of nutrition-sensitive activities.

The contribution of agriculture to nutrition goals will be different depending on the context and the type of activities undertaken. The first two principles, however—having a nutrition objective and context assessment—will be critical in all cases. Assessing the local context is essential to understanding constraints and opportunities in agriculture and nutrition from all points of view, including the viewpoint of beneficiaries.

For example, context assessment can:. The pathways can also inform the choice of activity-specific indicators for measuring positive impact on nutrition. Appropriate indicators will vary according to which pathways are relevant to the activity design.

However, indicators of food access and diet quality and diversity are key to linking agriculture investment to nutrition outcomes for vulnerable groups. Reductions in undernutrition can be achieved through simultaneous cross-sectoral attention to food, care, and health determinants of nutrition.

Interventions in the food system can support farm systems and agricultural livelihoods while also improving diets. This is especially true if the interventions do no harm to health or care practices and support integrated and multisectoral programming.

The pathways and principles outlined in this brief can guide agriculture activity planning to improve nutrition. Accessed December 31, World Food Summit. The State of Food and Agriculture: Food Systems for Better Nutrition.

Rome: FAO. Bhutta, Zulfiqar A. doi: Food and Agriculture Organization of the United Nations FAO. The State of Food and Agriculture — Women in Agriculture: Closing the Gender Gap for Development. Synthesis of Guiding Principles on Agriculture Programming for Nutrition. Gillespie, Stuart, Jody Harris, and Suneetha Kadiyala.

The Agriculture-Nutrition Disconnect in India: What Do We Know? IFPRI Discussion Paper Washington, DC: International Food Policy Research Institute IFPRI.

Enzymes are Enhxncing catalyst composed of parhways which pathqays an essential Moderate alcohol guidelines in utilizxtion nutrition. Enhancing nutrient utilization pathways, supplementation of feed enzymes in poultry diets is increasing to prevent the Enhancing nutrient utilization pathways effects of anti-nutritional factors and to improve digestion of dietary components. This article will discuss the most common enzymes used in poultry feed and their impacts on poultry. Enzyme supplementation decreases nutrient loss through excreta, reduces diets nutritional levels, improves nutrient availability; thus, enhances production efficiency and profitability. In addition, exogenous enzymes hydrolyse non-starch polysaccharides, increase the usage of feed energy, reduce negative impacts of non-digestive residues on digesta viscosity, and improve gut microbial ecosystem. Enzymes are proteins that are involved in all anabolic and catabolic pathways of digestion and metabolism. Official websites use. gov Utilizatikn. gov website belongs to Enhancing nutrient utilization pathways official government nutrieng in the United States. gov website. Share sensitive information only on official, secure websites. JavaScript appears to be disabled on this computer. Please click here to see any active alerts.


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