Plant Macronutrient Research Articles

Impact of various irrigation levels and nitrogen rates on wheat (Triticum aestivum L.) yield and nitrate leaching

BackgroundNitrogen (N) is a crucial macronutrient for plants and serves as a significant measure of soil productivity. The leaching of N-nitrate creates significant hazards for human health and ground water quality. Supplemental irrigation applied to various field crops significantly alters crop yield and nitrate (NO3–) leaching within the soil. Determining the influence of various N rates and irrigation levels on yield and NO3– leaching could help to select the optimum combination of irrigation and N. MethodsThe influence of various irrigation levels and N rates on NO3– leaching, soil physicochemical characteristics and grain yield of wheat crop was investigated. Two irrigation levels, i.e., I1 and I2 (60% and 75% of field capacity) and three N levels, i.e., 105, 130 and 160 kg/ha named as N1, N2 and N3 were included in the study. The irrigation and N levels were optimized in preliminary studies. Data relating to yield-related characteristics of wheat and soil physicochemical properties were recorded. ResultsThe growth and yield traits of the wheat crop were considerably influenced by varying degrees of irrigation N application. The interactive effect of I2N3 resulted in the highest numbers of tillers m−2 (18.9), 1000-grain weight (40.3 g), and straw (5.87 t ha−1) and grain (4.17 t ha−1) yields. Irrigation significantly affected infiltration rate, hydraulic conductivity of the saturated soil and soil strength. The bulk density of soil increased, while soil porosity decreased with increasing depth. Economic analysis revealed that higher irrigation and N levels, i.e., I2N3 resulted in the highest net economic returns. The NO3– concentration was significantly affected by soil depth and time after application of fertilizer. The NO3– concentration exhibited its greatest value at a depth of 0.35 m, while its lowest value was seen at a depth of 1 m. In addition, the concentration of NO3– exhibited a decline throughout the course of time after the administration of N. ConclusionIt is concluded that higher application of irrigation water and N fertilizer increased wheat yield and economic returns, and NO3– leaching. Therefore, alternative N sources with lower NO3– leaching must be used to reduce the adverse impacts on groundwater and environment.

Nitrogen addition and mowing had only weak interactive effects on macronutrients in plant-soil systems of a typical steppe in Inner Mongolia

Effective management of macronutrients is pivotal in the optimization and provisioning of ecosystem services in grassland areas, particularly in degraded grasslands. In such instances where mowing and nitrogen (N) fertilization have emerged as predominant management strategies, nutrient management is especially important. However, the precise effects of these concurrent practices on the distribution of macronutrients in plant-soil systems remain unclear. Here we evaluated the effects of 12 years of N addition (2, 10, and 50 g N m−2 year−1) and mowing on the concentrations and pools of six macronutrients (i.e., N; phosphorus P; sulfur S, calcium Ca, magnesium Mg, and potassium K) in three plant components (aboveground plants, litter, and belowground roots) at the community level and in the soil in a typical steppe in Inner Mongolia. Our results revealed that N addition generally raised the N concentration in the entire plant-soil system, regardless of whether plots were mowed. Higher N addition (10 and 50 g N m−2 year−1) also led to higher concentrations of P (+22%, averaging two N addition rates), S (+16%), K (+22%), Ca (+22%), and Mg (+24%) in plants but lower concentrations of these nutrients in the litter. Similar decreases in K (−9%), Ca (−46%), and Mg (−8%) were observed in the roots. In light of the observed increases in vegetation biomass and the lack of pronounced changes in soil bulk density, we found that the ecosystem N enrichment resulted in increased pools of all measured macronutrients in plants, litter, and roots (with the exception of Ca in the roots) while concurrently decreased the pools of P (−20%, averaging two higher N addition rates), S (−12%), K (−10%), Ca (−37%), and Mg (−19%) in the soil, with no obvious effect of the mowing practice. Overall, mowing exhibited a very limited capacity to alleviate the effects of long-term N addition on macronutrients in the plant-soil system. These findings highlight the importance of considering the distribution of macronutrients across distinct plant organs and the dynamic nutrient interplay between plants and soil, particularly in the context of long-term fertilization and mowing practices, when formulating effective grassland management strategies.

Precise analysis of potassium isotopic composition in plant materials by multi-collector inductively coupled plasma mass spectrometry

Potassium (K) is a crucial macronutrient for plants and is the predominant inorganic cation in plants, constituting up to 10% of plant biomass on a dry weight basis and originating from the soil. The utilization of potassium isotopes enables the examination of potassium cycling in the soil-plant. In this investigation, the potassium isotopic composition (δ41K) of five certified plant reference materials with varying potassium concentrations (BCR 679, GSV-2, GSB-2a, GSB-3 and GSB-6a) was assessed using multi-collector inductively coupled plasma mass spectrometry technique, employing a reduced Radio Frequency (RF) forward power and low-resolution mode without collision cell. The δ41K values of the plant reference materials BCR 679, GSV-2, GSB-2a, GSB-3 and GSB-6a are reported as −2.44 ± 0.03‰, −0.37 ± 0.04‰, −0.37 ± 0.05‰, −1.27 ± 0.04‰ and − 0.62 ± 0.01‰, respectively. This study not only presents the δ41K values of plants but also establishes a methodology for the pre-treatment and determination of δ41K in plant. Additionally, the observed variations in δ41K values among the plant reference materials suggest that δ41K has the potential to serve as a significant tracer in “soil-plant systems” within ecosystems.

Proteaceae species show different strategies for phosphorus acquisition and utilisation in P poor soils in the Mediterranean-type Fynbos ecosystem

Phosphorus is an essential plant macronutrient, but is deficient in soils of nutrient-poor ecosystems. Proteaceae members are characteristic of P-impoverished soils and as such, they have a specialised root adaptation, namely proteoid roots. Proteoid or cluster roots increase P acquisition from the soil for various families that occur in P-impoverished soils. Cluster root function has been shown to be dependent on edaphic features such as soil pH and P availability. Thus, the aim of this study was to assess whether two Protea proteoid rooted systems function with similar adaptive acquisition and utilisation strategies in different P-impoverished soils. Plant and soil material were sampled from two Protea species, P. repens (L.) L. and P. longifolia (A.) A., in their natural habitat. Ecto- and endo-enzymatic activities from samples were conducted to assess their acquisition and utilisation strategies each species employs, as a response to P deficiency. Protea longifolia ecto- and endo-enzymatic activities were significantly higher compared to P. repens. As P. longifolia occurred in more P-deficient soils, the ability to increase P acquisition and utilisation would be beneficial in maintaining its position in the ecosystem. Therefore, P utilisation and acquisition by these two species appear to be influenced by soil P bioavailability; playing an important role in determining adaptive mechanisms utilised by proteoid rooted species.

The transcription factor BnaA9.WRKY47 coordinates leaf senescence and nitrogen remobilization in Brassica napus.

Nitrogen (N) is an essential macronutrient for plants, and N remobilization is key for plant adaptation to N deficiency stress. However, there is a limited understanding of the regulatory mechanisms of N remobilization in Brassica napus. Here, we report a transcription factor, BnaA9.WRKY47, induced by N starvation. At the seedling stage, BnaA9.WRKY47-OE lines displayed earlier senescence of older leaves and preferential growth of juvenile leaves compared to the wild-type 'Westar 10' under N starvation. At the field scale, the seed yield was significantly increased in BnaA9.WRKY47-OE lines compared to 'Westar 10' grown under N deficiency conditions and, conversely, reduced in BnaA9.WRKY47-mutants. Biochemical analyses demonstrate that BnaA9.WRKY47 directly activates BnaC7.SGR1 to accelerate older leaf senescence. In line with leaf senescence, the amino acid concentration was elevated, and the N distribution was reduced in the older leaves of OE lines. This result is because BnaA9.WRKY47 activates the amino acid permease BnaA9.AAP1 and the nitrate transporter BnaA2.NRT1.7. Therefore, the expression of BnaA9.WRKY47 efficiently facilitates N remobilization from older to younger leaves or seeds. Taken together, the results of this study demonstrate that BnaA9.WRKY47 upregulates the expression of BnaC7.SGR1, BnaA2.NRT1.7 and BnaA9AAP1 thus promoting the remobilization of N in B. napus under N starvation.

Effect of Plant Defenses and Plant Nutrients on the Performance of Specialist and Generalist Herbivores of Datura: A Macroevolutionary Study.

Macroevolutionary patterns in the association between plant species and their herbivores result from ecological divergence promoted by, among other factors, plants' defenses and nutritional quality, and herbivore adaptations. Here, we assessed the performance of the herbivores Lema trilineata daturaphila, a trophic specialist on Datura, and Spodoptera frugiperda, a polyphagous pest herbivore, when fed with species of Datura. We used comparative phylogenetics and multivariate methods to examine the effects of Datura species' tropane alkaloids, leaf trichomes, and plant macronutrients on the two herbivores´ performances (amount of food consumed, number of damaged leaves, larval biomass increment, and larval growth efficiency). The results indicate that species of Datura do vary in their general suitability as food host for the two herbivores. Overall, the specialist performs better than the generalist herbivore across Datura species, and performance of both herbivores is associated with suites of plant defenses and nutrient characteristics. Leaf trichomes and major alkaloids of the Datura species are strongly related to herbivores' food consumption and biomass increase. Although hyoscyamine better predicts the key components of the performance of the specialist herbivore, scopolamine better predicts the performance of the generalist; however, only leaf trichomes are implicated in most performance components of the two herbivores. Nutrient quality more widely predicts the performance of the generalist herbivore. The contrasting effects of plant traits and the performances of herbivores could be related to adaptive differences to cope with plant toxins and achieve nutrient balance and evolutionary trade-offs and synergisms between plant traits to deal with a diverse community of herbivores.

Transhumance, shielings and soil fertility – land-use legacies in Menstrie Glen, Scotland

ABSTRACT Whilst transhumance has been researched as a livestock and land management system, its legacy on soil- nutrient levels is unknown. This study addresses changes in soil chemistry associated with historical transhumance grazing management with the aim of establishing if soil-nutrient levels can shed new insights into land-use legacies originating from past transhumance in Scotland. The study is focused on one aspect of transhumance, the shielings associated with milking livestock formerly operating in the uplands of the Scottish Midland Valley. A literature review is presented focusing on the history, functioning and geographic distribution of transhumance systems in Scotland set within a global context. This is followed by a detailed examination of two shieling sites in Menstrie Glen in the Ochil Hills. Their relationship to topography is considered, with vegetation survey and chemical analyses for plant macronutrients of soils collected in the vicinity also carried out. Underpinned by theories integrating biogeochemical fluxes and agropastoral activities it is established that there is moderate enrichment of local nutrient levels still evident at the Menstrie Glen shieling sites today. Review of historical and environmental sources suggests that local nutrient levels reflect temporal dynamics of shieling establishment, functioning and abandonment with limited evidence to suggest this was driven by population pressure and adaptation to Little Ice Age climate change. The analyses lead to insights about wider ecological impacts of different forms of land use in the face of climate change and population pressure, carrying implications for land use in Scotland and the challenges facing extant transhumance systems in countries where both these issues are pressing today.

Improvement of Nutrient Uptake, Yield of Black Sesame (Sesamum indicum L.), and Alluvial Soil Fertility in Dyke by Spent Rice Straw from Mushroom Cultivation as Biofertilizer Containing Potent Strains of Rhodopseudomonas palustris.

The aim of the current research was to evaluate the effects of members of purple nonsulfur bacteria (PNSB), Rhodopseudomonas palustris strains of VNW02, TLS06, VNW64, and VNS89, mixed with spent rice straw (SRS) from mushroom cultivation as a carrier on promoting sesame growth and yield, and ameliorating the alluvial soil (AS) fertility in dykes. A 4 × 3 factorial experiment consisting of different levels of the solid PNSB biofertilizer mixture at 0, 3, 4, and 5 t·ha-1 (0, 1.81 × 108, 2.24 × 108, and 2.68 × 108 cells pot-1, respectively), and nitrogen (N) and phosphorus (P) inorganic fertilizer rates (100, 75, and 50 kg·N·ha-1; 60, 45, and 30 kg P2O5·ha-1, respectively) was performed in pots with the sesame variety of ADB1 in the dyked AS. The solid PNSB biofertilizer mixture at at least 3 t·ha-1 significantly enhanced the sesame seed yield by providing higher macronutrients for plants by increasing available N and soluble P concentrations in the soil. The solid PNSB biofertilizer mixture in addition to 75% of the recommended N and P fertilizers produced an equivalent yield in comparison to the utilized 100% of N and P inorganic fertilizers. The solid PNSB biofertilizer mixture in the SRS from the mushroom production reduced at least 25% of N and P chemical fertilizers for gaining the maximal seed yield and enriched soil characteristics for the sustainable black sesame cultivation in the dyked AS.

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.).

Nitrogen (N) is an essential macronutrient for plants, acting as a common limiting factor for crop yield. The application of nitrogen fertilizer is related to the sustainable development of both crops and the environment. To further explore the molecular response of sugar beet under low nitrogen (LN) supply, transcriptome analysis was performed on the LN-tolerant germplasm '780016B/12 superior'. In total, 580 differentially expressed genes (DEGs) were identified in leaves, and 1,075 DEGs were identified in roots (log2 |FC| ≥ 1; q value < 0.05). Gene Ontology (GO), protein-protein interaction (PPI), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses clarified the role and relationship of DEGs under LN stress. Most of the downregulated DEGs were closely related to "photosynthesis" and the metabolism of "photosynthesis-antenna proteins", "carbon", "nitrogen", and "glutathione", while the upregulated DEGs were involved in flavonoid and phenylalanine biosynthesis. For example, GLUDB (glutamate dehydrogenase B) was identified as a key downregulated gene, linking carbon, nitrogen, and glutamate metabolism. Thus, low nitrogen-tolerant sugar beet reduced energy expenditure mainly by reducing the synthesis of energy-consuming amino acids, which in turn improved tolerance to low nitrogen stress. The glutathione metabolism biosynthesis pathway was promoted to quench reactive oxygen species (ROS) and protect cells from oxidative damage. The expression levels of nitrogen assimilation and amino acid transport genes, such as NRT2.5 (high-affinity nitrate transporter), NR (nitrate reductase [NADH]), NIR (ferredoxin-nitrite reductase), GS (glutamine synthetase leaf isozyme), GLUDB, GST (glutathione transferase) and GGT3 (glutathione hydrolase 3) at low nitrogen levels play a decisive role in nitrogen utilization and may affect the conversion of the carbon skeleton. DFRA (dihydroflavonol 4-reductase) in roots was negatively correlated with NIR in leaves (coefficient = -0.98, p < 0.05), suggesting that there may be corresponding remote regulation between "flavonoid biosynthesis" and "nitrogen metabolism" in roots and leaves. FBP (fructose 1,6-bisphosphatase) and PGK (phosphoglycerate kinase) were significantly positively correlated (p < 0.001) with Ci (intercellular CO2 concentration). The reliability and reproducibility of the RNA-seq data were further confirmed by real-time fluorescence quantitative PCR (qRT-PCR) validation of 22 genes (R2 = 0.98). This study reveals possible pivotal genes and metabolic pathways for sugar beet adaptation to nitrogen-deficient environments.

Warming reduces both photosynthetic nutrient use efficiency and water use efficiency in Mediterranean shrubsWarming reduces nutrient use efficiency

The ratio between net photosynthetic rates and the foliar contents of essential plant macronutrients (N, P, K) is termed photosynthetic nutrient use efficiency (PNutUE). A universal trade-off exists whereby plants cannot maximize their PNutUE and their intrinsic water use efficiency (WUEi, carbon gain per unit water spent) simultaneously, because any increase in intercellular CO2 concentration (ci) through a greater stomatal opening would increase PNutE but also enhances transpiration and therefore decreases WUEi. Rising temperatures associated with climate change can result in large decreases in WUEi in semiarid shrubs through photosynthetic machinery impairment and enhanced stomatal conductance and transpiration, but we know remarkably little about the influence of warming and drought on PNutUE and its interplay with WUEi in dryland vegetation. Using a 6-year (2011–2017) manipulative field experiment, we examined the effects of warming (2.5ºC, W), rainfall reduction (30%, RR), and their combination (W+RR) on the photosynthetic use efficiency of three essential nutrients (PNUE, PPUE and PKUE) and on WUEi in three shrub species growing at two semiarid shrublands for the years 2015–2017. Across species, warming (W and W+RR) reduced PNUE by 42.9%, PPUE by 43.8% and PKUE by 41.5% on average relative to shrubs growing under ambient temperatures, whereas RR did not significantly affect their PNutUE. These drastic reductions in PNutUE with warming were mainly driven by non-stomatal and largely non-nutritional decreases in net photosynthetic rates, which were almost halved in warmed shrubs. The photosynthetic use efficiencies of N, P and K were inversely related to foliar δ13C, a proxy for time integrated WUEi, in both ambient (control and RR) and warmed (W and W+RR) shrubs, but with significantly smaller slopes and intercepts for warmed shrubs. Thus, plants achieve a smaller gain in PNutUE for any given increase in stomatal conductance (and reduction in WUEi) under warmer climatic conditions. The strong negative impact of warming on PNutE, along with the warming-induced shift in the trade-off between PNutUE and WUEi, could be indicative of an increasing inability of native plants to cope with warmer conditions, with dire implications for dryland vegetation productivity and survival under climate change.

The alleviation of ammonium toxicity in plants.

Nitrogen (N) is an essential macronutrient for plants and profoundly affects crop yields and qualities. Ammonium (NH4 + ) and nitrate (NO3 - ) are major inorganic N forms absorbed by plants from the surrounding environments. Intriguingly, NH4 + is usually toxic to plants when it serves as the sole or dominant N source. It is thus important for plants to coordinate the utilization of NH4 + and the alleviation of NH4 + toxicity. To fully decipher the molecular mechanisms underlying how plants minimize NH4 + toxicity may broadly benefit agricultural practice. In the current minireview, we attempt to discuss recent discoveries in the strategies for mitigating NH4 + toxicity in plants, which may provide potential solutions for improving the nitrogen use efficiency (NUE) and stress adaptions in crops.

Effect of mycorrhizae on phosphate fertilization efficiency and maize growth under field conditions

Phosphorus (P) is a plant macronutrient that is indispensable for maize (Zea mays L.) production. However, P is difficult to manage in weathered soils, and its fertilization practice has low efficiency because it becomes unavailable for absorption by plant roots. Symbiosis of plants with arbuscular mycorrhizal fungi increases plant growth and enhances P uptake from the soil that is not directly available to the roots. Thus, the objective of this study was to determine how inoculation with Rhizophagus intraradices and phosphate fertilization interacts and influences the development and productivity of second-crop maize. The experiment was conducted in Selvíria, Mato Grosso do Sul, Brazil, in 2019 and 2020, both in a Typic Haplorthox. A randomized block design in subdivided plots was used for the phosphate application during crop sowing (0, 25, 50, 75, and 100% concentrations of the recommended level), and the secondary treatments were the doses of mycorrhizal inoculant (0, 60, 120 and 180 g ha−1) applied to the seed using a dry powder inoculant containing 20,800 infectious propagules per gram of the arbuscular mycorrhizal fungus R. intraradices. Only in the first year of the experiment, inoculation and phosphate fertilization promoted benefits to the maize crop, indicating potential to increase yield.

Fertiliser Properties of Wastewater Sludge and Sludge Ash - A Case Study from the Finnish Forest Industry

Abstract In this case study we compared the fertiliser properties of an industrial wastewater treatment sludge and a sludge ash to the requirements of the Finnish Fertiliser Product Decree. The sludge was obtained from the activated sludge wastewater treatment plant of a Finnish non-integrated pulp mill. The sludge was furthermore incinerated at a laboratory in a muffle furnace (850 °C) to obtain sludge ash. The total Cd (4.9 mg/kg d.m.) concentration in the pulp sludge exceeded the Finnish limit value (1.5 mg/kg d.m.) for fertiliser products used in agriculture. In the sludge ash, the total concentration of Cd (39 mg/kg; d.m.) exceeded the Finnish limit value (25 mg/kg d.m.) for ash fertilisers used in forestry. These results restrict the potential reuse options of these residues. However, from the utilisation point of view, the enrichment of essential plant macro-nutrients was most notable, resulting to the following total concentrations of these elements in the sludge ash: P (26,000 mg/kg d.m.), S (40,000 mg/kg d.m.), K (11,000 mg/kg d.m.), Ca (83,000 mg/kg d.m.) and Mg (10,000 mg/kg d.m.). Therefore, we conclude that, the converting of sludge into ash may promote the reuse of this wastewater treatment residue to a more value-adding fertiliser by-product to be used as a soil improver and growing medium in landscaping or landfills sites or other closed industrial areas, where heavy metal limit values for fertilisers are not applied in Finland.

Nitrogen Nutrition Differentially Affects Concentrations of Photosynthetic Pigments and Antioxidant Compounds in Mexican Marigold (Tagetes erecta L.)

Nitrogen is a major plant macronutrient and its supply affects the entire metabolism of plants. This study evaluated the effect of different nitrogen concentrations in the nutrient solution: 0, 4.2, 8.4, and 12.6 mg L−1 Mexican marigold (Tagetes erecta L.) var. Inca plants in an open soilless culture system under greenhouse conditions on the concentration of chlorophylls, carotenoids, phenolics, and flavonoids derived from the secondary metabolism, as well as on the antioxidant activity in different tissues. With the 12.6 mg N L−1 dose, chlorophylls a, b, and total chlorophyll concentrations increased by 98.8, 11.9, and 56.6%, respectively. The highest concentrations of total carotenoids in flowers, 28–30%, were recorded in plants with doses of 8.4 mg N L−1. With doses of 12.6 mg N L−1, phenolic compounds and total flavonoids increased in leaves, but decreased in flowers. The low and medium N concentrations increased the antioxidant activity with respect to the control without N by 53% and 50.2%, respectively. We conclude that the applications of N in Tagetes erecta differentially affected the concentrations of photosynthetic pigments and biomolecules with antioxidant capacity, and that such effects were dependent on the doses of N tested and the plant organ evaluated.

CONVERSION OF KITCHEN FOOD WASTE TO HALAL ORGANIC FERTILIZERS

Food produced for human consumption can be wasted up to one-third of the time, causing economic, social, and environmental harm. The value of kitchen food waste is being increasingly recognised, and Brunei Darussalam ranks among the highest in the region, with a solid waste output of 1.4 kg per capita per day. However, just 11.3% of food waste is estimated to have been recycled, with the remainder ending up in landfills. In this context, the purpose of this paper is to provide recommendations for the most environmentally friendly means of disposing of kitchen food waste, with composting providing natural, halal, eco-friendly fertiliser. Thus, a two-month experiment was conducted to produce compost-based fertilizer from kitchen food waste. The nutritional value of the plant was then ascertained by fertilizing one plant of bird’s eye chillies (Capsicum frutescens L) with compost-based fertilizer (CBF) and another plant with clay-based soil (CBS). The results of this study showed that almost all the macronutrients in CBF plants are in the accepted range and show good compost fertilisation. Thus, it demonstrates how composting food waste from households can aid in the management of waste reduction for sustainable and a healthy environment, and nutrient recycling in agriculture.

Transcription factor OsNAC016 negatively regulates phosphate-starvation response in rice

Phosphate (Pi), the main form of inorganic phosphorus that can be absorbed by plants, is one of the most limiting macro-nutrients in plants. However, the underlying molecular mechanism determining how plants sense external Pi levels and reprogram transcriptional and adaptive responses is incompletely understood. At present, few rice NAC members have been reported to be involved in the signaling pathways of Pi homeostasis in plants. Here, our research demonstrated that OsNAC016, a Pi-starvation responsive gene in rice, was regulated by PHOSPHATE STARVATION RESPONSE protein 1 (OsPHR1) and OsPHR4. Under Pi-starvation stress, the root growth of OsNAC016-overexpression lines was inhibited more severely, and overexpression plants had lower Pi content than wild type, while osnac016 mutant was hyposensitive to Pi starvation, indicating that OsNAC016 negatively modulates rice Pi-starvation response. Chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) analysis and transient transactivation assays indicated that OsNAC016 could activate the SPX-domain-containing protein 2 (OsSPX2) gene through binding to its promoter. Further, we found that Pi starvation enhanced OsNAC016 binding to the OsSPX2 promoter, thus strongly promoting OsSPX2 expression. At the same time, Pi starvation induced OsNAC016 protein accumulation in plants. Moreover, similar to OsSPX2, OsNAC016 negatively regulates leaf inclination by repressing the cell elongation in lamina joint in rice under Pi-starvation stress. Together, our findings demonstrate that OsNAC016 negatively regulates rice phosphate-starvation response and leaf inclination by activating OsSPX2 expression under Pi-starvation conditions. These data provide a strategy to create smart crops with ideal shoot architecture and high phosphorus utilization efficiency.

Macronutrient omission influences morphological parameters, growth, and yield in Arracacia xanthorrhiza Bancroft

Mineral nutrition in arracacha is a critical production factor that conditions harvest yield. Few studies have been developed in nutrition and physiology, this does not allow to the design of ideal fertilization programs; consequences are increased production costs, soil degradation, and low-quality storage roots. Therefore, this study aimed to characterize the symptoms associated with macronutrient deficiency in arracacha plants and its effect on morphological parameters, the accumulation of fresh and dry biomass, and the distribution of dry matter in the different organs. Under greenhouse conditions, the experiment was conducted in Cajamarca, Tolima, Colombia. A completely randomized design was implemented, with seven treatments and six replicates (6 solutions lacking N, P, K, Ca, Mg, and S and Hoagland complete solution). Forty-two seedlings were transplanted, to which the complete solution was applied for 75 days, increasing the concentrations from 0.25 M to 1 M, and then nutritional deficiencies were induced. Deficiencies caused by macronutrients in arracacha plants exhibited visual symptoms and changes in their morphology. The omission of N, Ca, and S generated the most severe symptoms, drastically affecting plant height, leaf width, number of leaves, and plant mass accumulation. In the case of P, leaves became small and intense green with a violet margin. The Mg and K generated leaves with interveinal and margin chlorosis. Plants with the omission of macronutrients allocated dry mass in the following order: stem, storage roots, propagules, and leaves.

The anion channel SLAH3 interacts with potassium channels to regulate nitrogen-potassium homeostasis and the membrane potential in Arabidopsis.

Nitrogen (N) and potassium (K) are essential macronutrients for plants. Sufficient N and K uptake from the environment is required for successful growth and development. However, how N and K influence each other at the molecular level in plants is largely unknown. In this study, we found loss-of-function mutation in SLAH3 (SLAC1 HOMOLOGUE 3), encoding a NO3- efflux channel in Arabidopsis thaliana, enhanced tolerance to high KNO3 concentrations. Surprisingly, slah3 mutants were less sensitive to high K+ but not NO3-. Addition of NO3- led to reduced phenotypic difference between wild-type and slah3 plants, suggesting SLAH3 orchestrates NO3--K+ balance. Non-invasive Micro-test Technology analysis revealed reduced NO3- efflux and enhanced K+ efflux in slah3 mutants, demonstrating that SLAH3-mediated NO3- transport and SLAH3-affected K+ flux are critical in response to high K +. Further investigation showed that two K+ efflux channels, GORK (GATED OUTWARDLY-RECTIFYING K+ CHANNEL) and SKOR (STELAR K+ OUTWARD RECTIFIER), interacted with SLAH3 and played key roles in high K+ response. The gork and skor mutants were slightly more sensitive to high K+ conditions. Less depolarization occurred in slah3 mutants and enhanced depolarization was observed in gork and skor mutants upon K+ treatment, suggesting NO3-/K+ efflux-mediated membrane potential regulation is involved in high K+ response. Electrophysiological results showed that SLAH3 partially inhibited the activities of GORK and SKOR in Xenopus laevis oocytes. This study revealed that the anion channel SLAH3 interacts with the potassium channels GORK and SKOR to modulate membrane potential by coordinating N-K balance.

Calcium's multifaceted functions: From nutrient to secondary messenger during stress

An essential macronutrient for plants, calcium (Ca2+) is needed for a variety of functions both under normal and stressful situations. It displays characteristics of a structural component and acts as a secondary messenger during several physiological processes. It behaves as a signaling molecule while under stress. It manifests a variety of symptoms, such as weakening the cell wall, at lower concentrations or in insufficient situations, demonstrating its significant significance at peak levels. Calcium is taken up by roots through a variety of channels or proteins that are positioned on the plasma membrane. These channels are divided into three categories based on their electrophysiological properties: voltage-independent channels (VICs), hyperpolarization-activated channels (HACCs), and depolarization-activated channels (DACCs). Protein channels allow it to enter the cytosol, where it is then exported towards the apoplast or xylem by Ca2+/H+ antiporters or Ca2+-ATPases. In addition to these, Ca2+ also functions as a secondary messenger throughout physiological, stress-related, and developmental events. The interaction of pumps and influx exporters/channels, also known as calcium signatures, is what causes the signal to be produced. The primary decoding proteins for reactions are calmodulins (CaM), calmodulin-like proteins (CMLs), calcineurin B-like proteins (CBLs), CBL-interacting protein kinases (CIPKs), and calcium-dependent protein kinases (CDPKs/CPKs). After the signals have been processed, transporters, transcription factors, and channels then transmit them into outputs, which lead to the shutting of stomata and gene expression. Ca2+ homeostasis is also preserved during signaling by several transporting components that control the outflow and import of Ca2+, respectively. These transporters include Ca2+-ATPases, Ca2+/H+ exchangers, Mechanosensitive channels (MSLs), Cyclic nucleotide-gated channels (CNGCs), Two Pore Channels (TPCs), Glutamate-like Receptor channels (GLRs), and Ca2+/cation exchangers (CCXs). Due to their sessile nature, plants have been subjected to a range of environmental challenges, including nutrient deficit, metal stress, temperature stress and drought. To investigate the many roles that calcium plays, this review has gone into detail about the various processes via which Ca2+ has been studied to play a part throughout these stresses.

Breeding and genomics approaches for improving phosphorus-use efficiency in grain legumes

Phosphorus (P) is an essential plant macronutrient, but P sources for plant growth are non-renewable, causing great concern for future sustainable agriculture and global food security. Thus, enhancing plant P-use efficiency (PUE) by improving P-acquisition and P-utilization efficiencies is urgently needed in various crops, including grain legumes, for intensive cropping systems. This review discusses how to harness the genetic variability in PUE traits across grain legume gene pools to improve PUE using various conventional breeding approaches and emerging breeding tools. The genetic architecture of PUE traits is complex, being quantitatively inherited and highly influenced by the environment. Thus, we discuss how the biparental QTL mapping approach has been used to dissect the genetic architecture of PUE traits. Unprecedented advances in legume genomics resources, especially high-throughput single nucleotide polymorphisms, have facilitated uncovering genomic regions related to PUE across the whole genome using a genome-wide association mapping approach. Likewise, the availability of complete genome sequence information, pangenome sequences, and the whole-genome resequencing approach have provided novel insights into structural variation, including presence/absence and copy number variations, underpinning PUE. Simultaneously, progress in functional genomics, including transcriptomics and computational biology, has facilitated the discovery of various underlying transcription factors and the corresponding downstream P signal perception genes and candidate gene(s) controlling PUE and conferring low-P tolerance in various legumes with putative function. We also discuss updated metabolomics and proteomics approaches that have improved our understanding of various gene networks, P-starvation signaling pathways, and P acquisition and utilization of molecular mechanisms important for PUE. Finally, we summarize how novel breeding schemes, including genomic selection, speed breeding, and emerging CRISPR/Cas9-based genome editing tools, will assist in designing P-use-efficient cultivars and adapting grain legumes to low-P environments. Thus, enhancing PUE by integrating various ‘omics’ approaches could improve P-acquisition and P-utilization efficiencies in various modern grain legume cultivars grown in intensive cropping systems to restrict P-fertilizer overuse and preserve the declining non-renewable global rock phosphate reservoir for securing an economical and sustainable future agriculture. • Phosphorus (P) is one of the most essential nutrients required for plant growth and development. • P fertilizers being non-renewable, judicious utilization of P fertilizer is urgently needed for sustaining legume yield for ensuring global food security. • Plants have evolved several molecular, physiological and biochemical mechanisms to sense, acquire and utilize soil P and adapt under P impoverished environments. • ‘Omics’ approach could greatly assist in unraveling the underlying genomic regions with their function contributing to improving phosphorus use efficiency in legume crops.