Functions In Plant Metabolism Research Articles

A review of potassium significance and management approaches in potato production under sandy soils

AbstractThis review focuses on the critical role of potassium (K) in potato cultivation, addressing its essential functions in plant metabolism and the challenges in managing soil K levels, specifically under sandy soils. The K use efficiency is higher in potatoes, with the maximum potential up to 55%, compared to cereals at 19%. Potatoes require high quantities of K, especially in well‐drained sandy soils, to maximise growth and yield. Because K is a highly leaching‐prone nutrient in these soils, its deficiencies could affect plant health, metabolism (K is required to activate more than 60 enzymes) and productivity. Optimal potato growth necessitates maintaining 1.8% K in the tubers, corresponding to a need of 0.22 kg K2O ac−1 for a substantial yield. The review article highlights the significant use of potash fertilisers in the United States, with an average consumption of 4.43 million metric tons between 2010 and 2021, underscoring the importance of K in agricultural practices. The paper also highlights the difference in K requirement and removal among different potato varieties that require the maximum amount in processing types. This manuscript discusses K's management schemes through soil testing, plant tissue analysis and artificial intelligence. The integration of various machine‐learning methods could offer promising prospects for predicting K response in potatoes, aiming to improve nutrient management and sustainable crop production. By synthesising current knowledge and advancements in K fertilisation techniques, this paper provides insights into overcoming the challenges of K management in potato cultivation, ultimately contributing to increased productivity and improved crop quality.

Combine Application of Zinc and Boron Improves Pearl Millet (Pennisetum glaucum) Performance Under No Tillage and Plough Tillage

No-tillage (NT) and crop rotation with green manure crops is a best alternative to plough tillage because it sustains environmental health, conserves natural resources and also improves crop growth and yield Conventional tillage practices result in losses of soil, water, and nutrients in the field, as well as degraded soils with low organic matter content and unstable physical structures, resulting in low crop yields and inefficient water and fertilizer usage. Micronutrient deficiencies, such as zinc (Zn) deficiency, is becoming more common in various annual crops as a result of continuous tillage. Zn has specific and essential physiological functions in plant metabolism, influencing yield and quality. Boron (B) plays an important role in the physiological process of plants, such as cell elongation, cell maturation, meristematic tissue development, and protein synthesis. To evaluate the role of Zn and B this experiment was performed in College of Agriculture BZU Bahaddar Sub Campus Layyah. Experiment was comprised of two tillage systems (No tillage and plough tillage) and three treatments application including (Zn, B, Zn+B) compared with control. These treatments were arranged according to RCBD split plot arrangement with net plot size of 1.8×4m. Findings of this study revealed that combine application of Zn and B boosted pearl millet growth and yield under no-tillage. Maximum relative water contents (RWC), membrane stability index (MSI), chlorophyll pigment, plant height, tillers per plant, leaf area index (LAI), stem diameter, length of ear head, seeds per ear, grain mass, grain yield, biological yield and 1000 grains were recorded when combine application of Zn and B was done under no-tillage. From the results it was concluded that pearl millet growth and yield can be maximized through combine application of Zn and B under no tillage.

Molecular hydrogen positively regulates nitrate uptake and seed size by targeting nitrate reductase.

Although the sources of molecular hydrogen (H2) synthesis in plants remain to be fully elucidated, ample evidence shows that plant-based H2 can regulate development and stress responses. Here, we present genetic and molecular evidence indicating that nitrate reductase (NR) might be a target of H2 sensing that positively regulates nitrogen use efficiency (NUE) and seed size in Arabidopsis (Arabidopsis thaliana). The expression level of NR and changes of NUE under control and, in particular, low nitrogen supply were positively associated with H2 addition supplied exogenously or through genetic manipulation. The improvement in nitrate assimilation achieved by H2 was also mediated via NR dephosphorylation. H2 control of seed size was impaired by NR mutation. Further genetic evidence revealed that H2, NR, and nitric oxide can synergistically regulate nitrate assimilation in response to N starvation conditions. Collectively, our data indicate that NR might be a target for H2 sensing, ultimately positively regulating nitrate uptake and seed size. These results provide insights into H2 signaling and its functions in plant metabolism.

Calcium isotope fractionation associated with adsorption and desorption on/from δ-MnO2

Small mineral particles present in soils, such as clay minerals and some oxyhydroxides, constitute important nutrient reservoirs. This behavior is due to the negative charges and high specific surface areas of these particles allowing them to adsorb cations such as calcium (Ca), a macronutrient that occupies key physiological and structural functions in plant metabolism. Although the chemical reactivity of clay minerals is rather well-known in the literature, especially toward macronutrients such as Ca, that of oxyhydroxides such as phyllomanganate minerals remains largely unexplored.To enhance our understanding of the mechanisms at the origin of the storage/release of the different isotopes of Ca in a soil solution, the possible fractionation between 40Ca and 44Ca during adsorption and desorption of Ca on a synthetic phyllomanganate, abiotically precipitated in the laboratory [synthetic analog of vernadite (δ-MnO2)], was studied. Experiments were performed in batch (closed system), and several parameters (time, pH of the solution, Ca concentration and nature and concentration of the desorbent) were tested to cover a large range of physicochemical conditions.This study demonstrated that the light 40Ca isotope is preferentially adsorbed on δ-MnO2, with Δ44/40Ca (the apparent fractionation of the aqueous solution at the stationnary state of adsorption compared to the initial one) of the adsorbed Ca that can reach 1.19 ± 0.15‰. The results showed that this isotopic fractionation occurs at chemical equilibrium in a closed system and that the isotopic fractionation measured in this study during Ca adsorption on phyllomanganate is significantly higher than that reported in the literature during Ca adsorption on other soil constituents such as clay minerals. At pH below 4 Ca occupies only the interlayer/basal sites whereas above this pH Ca fills interlayer/basal sites (∼86%) and edges sites (∼14%). By combining the experimental data obtained at different pH values, initial Ca concentrations and interaction times, our results suggest that isotopic signature of the Ca adsorbed on δ-MnO2 is dependent on the nature of the site involved in the adsorption step (i.e., enriched in 40Ca in the interlayer with Δ44/40Ca equal to −0.43‰ and enriched in 44Ca when bound to the edges with Δ44/40Ca equal to +3.5‰). As revealed by surface complexation modeling, such contrasting behavior between the two types of adsorption sites could be due to the bidendate nature of the Ca adsorption occurring on edges and to ion exchange of Ca2+ with H+ in the interlayer sites. Finally, desorption experiments point to total but not instantaneous Ca desorption, probably due to a partial collapse of the interlayer with some ions used to desorb Ca2+ (K+, NH4+, hexaamine-cobalt). This suggests that the amount of bioavailable Ca in soils by simple ion-exchange reactions is highly dependent on the nature of the ions which could desorb Ca present in the soil solution.

Macronutrients for Plants Growth and Humans Health

Macronutrients are crucial for the growth, and development of plants due to their roles as structural components and redox-sensitive agents. Generally, the application of macronutrients leads to increased crop output, growth, and overall quality. While macronutrients play a role in every stage of a plant's life, scientists in fields such as plant physiology, biotechnology, and eco-physiology have recently focused on exploring additional aspects of these minerals, and their potential. Each macronutrient has a unique function in plant metabolism, and this study aims to examine the latest advancements in understanding the specific roles of macronutrients in plant growth and acclimatization. Furthermore, the study also discusses future research prospects in this field, highlighting the importance of ongoing investigations in maximizing plant productivity, and resilience.

Plant mineral nutrition and disease resistance: A significant linkage for sustainable crop protection.

Complete and balanced nutrition has always been the first line of plant defense due to the direct involvement of mineral elements in plant protection. Mineral elements affect plant health directly by modulating the activity of redox enzymes or improving the plant vigor indirectly by altering root exudates, and changing microflora population dynamics, rhizosphere soil nutrient content, pH fluctuation, lignin deposition, and phytoalexin biosynthesis. Nitrogen (N) is one of the most important macronutrients having a significant impact on the host-pathogen axis. N negatively affects the plant's physical defense along with the production of antimicrobial compounds, but it significantly alleviates defense-related enzyme levels that can eventually assist in systemic resistance. Potassium (K) is an essential plant nutrient, when it is present in adequate concentration, it can certainly increase the plant's polyphenolic concentrations, which play a critical role in the defense mechanism. Although no distinguished role of phosphorus (P) is observed in plant disease resistance, a high P content may increase the plant's susceptibility toward the invader. Manganese (Mn) is one of the most important micronutrients, which have a vital effect on photosynthesis, lignin biosynthesis, and other plant metabolic functions. Zinc (Zn) is a part of enzymes that are involved in auxin synthesis, infectivity, phytotoxin, and mycotoxin production in pathogenic microorganisms. Similarly, many other nutrients also have variable effects on enhancing or decreasing the host susceptibility toward disease onset and progression, thereby making integrative plant nutrition an indispensable component of sustainable agriculture. However, there are still many factors influencing the triple interaction of host-pathogen-mineral elements, which are not yet unraveled. Thereby, the present review has summarized the recent progress regarding the use of macro- and micronutrients in sustainable agriculture and their role in plant disease resistance.

Effects of fused and blended fertilizers on maize yield and soil properties

AbstractThe deficiency of secondary and micronutrients negatively affects plant metabolic functions and reduces crop yields. These nutrients are applied in small quantities (<10 kg ha−1) and are physically blended or chemically fused with primary nutrients to enhance uniformity of application. A 3‐yr study (2012–2014) was conducted to evaluate the effects of fall or spring‐applied fertilizer N with or without P and N–P fertilizers containing S and Zn (blended or fused) on soil properties, leaf chlorophyll, and maize (Zea mays L.) yield in Nebraska. Response variables were measured for additional 2 yr (2015–2016; residual years [RYs]). Soil Mehlich‐3 P was low (14 mg kg−1) at the onset of the experiment and adding P increased grain yield by 10% compared with N only treatment in 2013–2015. Grain yields were similar in treatments with S and Zn fused (9.7–12.4 Mg ha−1) or blended (9.7–12.2 Mg ha−1) in all years (2012–2016). A yield benefit of adding S and Zn was recorded only 1 yr (2015: the first RY) (12.3 and 11.6 Mg ha−1 in NP treatments with and without S and Zn). Except for 2012, all fertilized treatments had greater yields than the control in 2013–2016. The 2012 was a dry year, where yield was low across the treatments (1.6–2.1 Mg ha−1) suggesting minimal benefits of adding primary nutrients (N, P), let alone S or Zn, when moisture is limiting. It is warranted that blended and fused fertilizers are evaluated under specific conditions where soils are deficient in constituent nutrients.

An Archaic Approach to a Modern Issue: Endophytic Archaea for Sustainable Agriculture

Archaea have existed for over 3.5 billion years, yet they were detected in the plant endosphere only in the recent past and still, not much is known about them. Archaeal endophytes may be important microorganisms for sustainable agriculture, particularly in the face of climate change and increasing food demand due to population growth. Recent advances in culture-independent methods of research have revealed a diverse abundance of archaea from the phyla Euryarchaeota, Crenarchaeaota, and Thaumarchaeota globally that are associated with significant crops such as maize, rice, coffee, and olive. Novel insights into the plant microbiome have revealed specific genes in archaea that may be involved in numerous plant metabolic functions including amino acid production and phytohormone modulation. This is the first review article to address what is known about archaea as endophytes, including their patterns of colonization and abundance in various parts of different crop plants grown under diverse environmental conditions. This review aims to facilitate mainstream discussions and encourage future research regarding the occurrence and role of endophytic archaea in plants, particularly in relation to agricultural applications.

Enantioselectivity and mechanisms of chiral herbicide biodegradation in hydroponic systems

This study demonstrates the enantioselective removal dynamics and mechanisms of the chiral herbicide metolachlor in a hydroponic system of Phragmites australis. It presents the first work to elucidate plant-microbial driven enantioselective degradation processes of chiral chemicals. The results showed a degradation efficiency of up to 95.07 ± 2.81% in the hydroponic system driven by a notably high degradation rate constant of 0.086 d−1. P. australis was demonstrated to rapidly increase the contribution of biodegradation pathways in the hydroponic system to 82.21 ± 4.81% within 4 d with an enantiomeric fraction (EF) drop to 0.26 ± 0.02 to favour the enantioselective degradation of S-Metolachlor (kS-Metolachlor = 0.568 d−1 and kR-Metolachlor = 0.147 d−1). Comparatively, the biodegradation pathways in the control constituted less than 25%, with an EF value of circa 0.5. However, the enantioselective biodegradation pathways exhibited complete reversal after about 4 d to favour R-Metolachlor. Plants promoted the degradation of R-Metolachlor, evidenced by an increase in EF to 0.59 ± 0.03. Nonetheless, metolachlor showed an inhibitory effect on plants reflected by the reduction of plant growth rate, chlorophyll content, and electron transport rate to −7.85 ± 1.52%, 1.33 ± 0.43 mg g−1, 4.03 ± 1.33 μmol (m2 s)−1, respectively. However, rhizosphere microorganisms aided plants to catalyze excessive reactive oxygen species production by the antioxidant enzymes to protect plants from oxidative damage and restore their physiological activities. High-throughput analysis of microbial communities demonstrated the enrichment of Massilia (40.63%) and Pseudomonas (8.16%) in the initial stage to promote the rapid degradation of S-Metolachlor. By contrast, the proliferation of Brevundimonas (32.29%) and Pseudarthrobacter (11.03%) in the terminal stage was closely associated with the degradation of R-Metolachlor. Moreover, as symbiotic bacteria of plants, these bacteria aided plants protection from reactive oxygen damages and promoted the recovery of plant metabolic functions and photosynthesis. Overall, these results demonstrate biodegradation mediated by plant-microbe mechanisms as the main driver for the enantioselective degradation of metolachlor in hydroponic systems.

A Circular Economy Approach to Restoring Soil Substrate Ameliorated by Sewage Sludge with Amendments.

This study examined the use of an artificial soil substrate in a mine waste reclamation area and its effect on plant metabolic functions. Research was conducted by determining the relationship between the plants’ biochemical features and the properties of plant growth medium derived from post-flotation coal waste, sewage sludge, crushed stone and fly ash on the surface of the mine waste disposal area. Trees and shrubs were established on the material and allowed to grow for eight years. The study determined that the applied plants and the naturally occurring Taraxacum officinale were suitable for physio-biochemical assessment, identification of derelict areas and reclamation purposes. An evaluation of a soil substrate applied to post-mining areas indicated that it was beneficial for plant growth since it activated the metabolic functions of herbaceous plants, shrubs, and trees. The study showed that soil substrate can be targeted to improve plant stress tolerance to potentially toxic elements (PTEs). These data suggest the potential for growth and slower susceptible response to Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. It is possible that the constructed soil-substitute substrate (biosolid material) would be an effective reclamation treatment in areas where natural soil materials are polluted by PTEs. This observation may reflect a more efficient use of soil substrate released from the cycling of organic biogene pools, in accordance with the circular economy approach. In further studies related to land reclamation using sewage sludge amendments, it would be necessary to extend the research to other stress factors, such as salinity or water deficiency.

What is a plant nutrient? Changing definitions to advance science and innovation in plant nutrition

Current definitions of essential or beneficial elements for plant growth rely on narrowly defined criteria that do not fully represent a new vision for plant nutrition and compromise fertilizer regulation and practice. A new definition of what is a plant nutrient that is founded in science and relevant in practice has the potential to revitalize innovation and discovery. A proposed new definition might read: A mineral plant nutrient is an element which is essential or beneficial for plant growth and development or for the quality attributes of the plant or harvested product, of a given plant species, grown in its natural or cultivated environment. A plant nutrient may be considered essential if the life cycle of a diversity of plant species cannot be completed in the absence of the element. A plant nutrient may be considered beneficial if it does not meet the criteria of essentiality, but can be shown to benefit plant growth and development or the quality attributes of a plant or its harvested product. It includes elements currently identified as essential, elements for which a clear plant metabolic function has been identified, as well as elements that have demonstrated clear benefits to plant productivity, crop quality, resource use efficiency, stress tolerance or pest and disease resistance. We propose an open scientific debate to refine and implement this updated definition of plant nutrients. Other outcomes of this debate could be a more precise definition of the experimental evidence required to classify an element as a plant nutrient, and an independent scientific body to regularly review the list of essential and beneficial nutrients. The debate could also attempt to refine the definition of plant nutrients to better align with nutrients deemed essential for animal and human nutrition, thus following a more holistic ’one nutrition‘ concept.

Agronomic Efficiency of Phosphorus Fertilizers With Associate Technology in Soy Crop in Cerrado Soil

For commercial soybean production, the presence of phosphorus in the soil is essential, not only to increase productivity but also because it affects basic functions in plant metabolism. Phosphate fertilizers have low efficiency in Cerrado soils. For this reason, the use of technologies associated with phosphate fertilizers is important to increase their efficiency in the soil. The experiment was conducted at Fazenda Rio Brilhante in Coromandel, MG. The experiment was laid out in a randomized block design in a 4 × 4 + 1 factorial arrangement. Treatments consisted of four phosphate fertilizer sources (MAPCONVENCIONAL, MAPpol 1, MAPpol 2, and FOM), four P2O5 doses (40, 80, 120, and 160 kg ha-1), and the control treatment (no phosphorus application). The soybean cultivar RK8115 IPRO with a plant population of 340 thousand plants per hectare was used. The experimental plots consisted of five planting lines with a spacing of 0.5 meters and a length of 7 meters. In the experiment, phosphorus leaf, morphological evaluation of plant height, stem diameter, number of stems, and pods were measured. For plant biomass, the dry matter of leaves, stems, and pods were determined. For yield evaluation, the calculation of productivity and RAE was compared with MAPCONVENCIONAL. For sources, data were subjected to analysis of variance, and means were separated by Tukey’s rate test (p < 0.05). For P2O5 doses, regression model fitting was performed using the ExpDes.pt package of R Studio software. Morphological assessments responded linearly to P doses, except for DPM. Leaves and pods P content and yield were affected by P dosage and P sources, with a quadratic response to P dosage. Maximum yield efficiency was achieved at P2O5 doses of 122.73; 145.07; 112.03; and 94.71 kg ha-1, with yields of 3818.30; 4064.67; 4089.03; and 3952.63 kg ha-1 for MAPCONVENCIONAL, MAPpol 2, MAPpol 1, and FOM, respectively. However, MAPpol 1 and FOM provided a dose reduction of 26 and 15 compared to the maximum yield of MAPCONVENCIONAL, respectively.

Olive Nutritional Status and Tolerance to Biotic and Abiotic Stresses.

The role of nutrients in plant growth is generally explained in terms of their functions in plant metabolism. Nevertheless, there is evidence that plant tolerance or resistance to biotic or abiotic stresses could be affected by the nutritional status. Although not well studied, an adequate nutritional status for optimal plant growth is thought to also be optimal for plant tolerance to stress. Considering the current global trend toward sustainability, studies that clarify the relationships between nutrition and stress are of great interest. For example, potassium plays an important role in the regulation of water status in the olive, improving drought tolerance, while calcium is involved in sodium exclusion mechanism, which can increase tolerance to salinity. Nitrogen excess, in contrast, increases susceptibility to spring frost and olive leaf spot. Silicon is not an essential element for plant growth, but it is considered a beneficial element; among its roles in the control of pests and diseases is the formation of a physical barrier that occurs through silicon deposition in the epidermal cells of the leaves. The presence of soluble silicon also facilitates the deposition of phenolic and other compounds at sites of infection, which is a general defense mechanism to pathogen attack. In olive, silicon application, either by foliar sprays or through irrigation water, reduces the incidence of olive leaf spot. This review summarizes the current status of olive nutrition, the relationships with biotic and abiotic stresses, and the effects of silicon.

Mediator function in plant metabolism revealed by large-scale biology.

Mediator is a multisubunit transcriptional co-regulator that is involved in the regulation of an array of processes including plant metabolism. The pathways regulated by Mediator-dependent processes include those for the synthesis of phenylpropanoids (MED5), cellulose (MED16), lipids (MED15 and CDK8), and the regulation of iron homeostasis (MED16 and MED25). Traditional genetic and biochemical approaches laid the foundation for our understanding of Mediator function, but recent transcriptomic and metabolomic studies have provided deeper insights into how specific subunits cooperate in the regulation of plant metabolism. In this review, we highlight recent developments in the investigation of Mediator and plant metabolism, with particular emphasis on the large-scale biology studies of med mutants.

English

Cadmium (Cd) toxicity has been a wide-spread phenomenon affecting plant metabolic functions due to excessive production of reactive oxygen species. This study was aimed at medium supplementation of optimized levels of growth modulators viz., salicylic acid (SA, 500 µM), ascorbic acid (AsA, 500 µM), thiourea (TU, 400 µM) and hydrogen peroxide (H2O2, 100 µM) in improving Cd tolerance in maize (Zea mays L. hybrid P-1543) in sand culture under net house conditions. All treatments were applied in the growing medium by dissolving in water. Results revealed that Cd stress (1000 µM) severely reduced the shoot and root dry mass and leaf area per plant and endogenous production of osmoprotectants (soluble sugars, free proline and glycinebetaine), phenolic compounds (soluble phenolics, flavonoids and anthocyanins) and vitamins (ascorbic acid, niacin and riboflavin) in shoot and root tissues indicating that Cd was highly toxic to the metabolic pathways. However, medium supplementation of the selected growth modulators was quite effective in reversing the Cd toxicity effect. Among the medium supplemented compounds, SA and AsA were more effective in reversing the Cd toxicity effect than TU and H2O2. Presence of tight correlations of growth attributes with metabolites levels substantiated that medium supplementation was greatly effective in orchestrating the endogenous metabolite levels and supporting maize growth under Cd toxicity. A greater effectiveness of the SA, AsA and TU can be attributed to their molecular structure and physiological properties in scavenging ROS and reducing oxidative stress. The results may have great promise and practical implications for growing maize successfully in the marginally Cd contaminated soils.

Ultrastructure of plastids serves as reliable abiotic and biotic stress marker.

Plastids perform many essential functions in plant metabolism including photosynthesis, synthesis of metabolites, and stress signaling. The most prominent type in green leaves is the chloroplast which contains thylakoids, plastoglobules, and starch. As these structures are closely linked to the metabolism of chloroplasts, changes during plant growth and development and during environmental stress situations are likely to occur. The aim of this study was to characterize changes in size and ultrastructure of chloroplast on cross-sections of leaves during high light stress, Botrytis infection, and dark induced senescence by quantitative transmission electron microscopy (TEM).The size of chloroplasts on cross sections of leaves decreased significantly when plants were subject to high light (49%), Botrytis infection (58%), and senescence (71%). The number of chloroplasts on cross sections of the palisade cell layer and spongy parenchyma, respectively, decreased significantly in plants exposed to high light conditions (48% and 29%), infected with Botrytis (48% and 46%), and during senescence (78% and 80%). Thylakoids on cross-sections of chloroplasts decreased significantly in plants exposed to high light (22%), inoculated with Botrytis cinerea (36%), and senescence (51%). This correlated with a massive increase in plastoglobules on cross-sections of chloroplasts of 88%, 2,306% and 19,617%, respectively. Starch contents on cross sections of chloroplasts were completely diminished in all three stress scenarios. These results demonstrate that the decrease in the number and size of chloroplasts is a reliable stress marker in plants during abiotic and biotic stress situations which can be easily detected with a light microscope. Further, lack of starch, the occurrence of large plastoglobules and decrease in thylakoids can also be regarded as reliable stress marker in plants which can be detected by TEM.

Proteomic analysis dissects the impact of nodulation and biological nitrogen fixation on Vicia faba root nodule physiology.

Symbiotic nitrogen fixation in root nodules of legumes is a highly important biological process which is only poorly understood. Root nodule metabolism differs from that of roots. Differences in root and nodule metabolism are expressed by altered protein abundances and amenable to quantitative proteome analyses. Differences in the proteomes may either be tissue specific and related to the presence of temporary endosymbionts (the bacteroids) or related to nitrogen fixation activity. An experimental setup including WT bacterial strains and strains not able to conduct symbiotic nitrogen fixation as well as root controls enables identification of tissue and nitrogen fixation specific proteins. Root nodules are specialized plant organs housing and regulating the mutual symbiosis of legumes with nitrogen fixing rhizobia. As such, these organs fulfill unique functions in plant metabolism. Identifying the proteins required for the metabolic reactions of nitrogen fixation and those merely involved in sustaining the rhizobia:plant symbiosis, is a challenging task and requires an experimental setup which allows to differentiate between these two physiological processes. Here, quantitative proteome analyses of nitrogen fixing and non-nitrogen fixing nodules as well as fertilized and non-fertilized roots were performed using Vicia faba and Rhizobium leguminosarum. Pairwise comparisons revealed altered enzyme abundance between active and inactive nodules. Similarly, general differences between nodules and root tissue were observed. Together, these results allow distinguishing the proteins directly involved in nitrogen fixation from those related to nodulation. Further observations relate to the control of nodulation by hormones and provide supportive evidence for the previously reported correlation of nitrogen and sulfur fixation in these plant organs. Additionally, data on altered protein abundance relating to alanine metabolism imply that this amino acid may be exported from the symbiosomes of V. faba root nodules in addition to ammonia. Data are available via ProteomeXchange with identifier PXD008548.

Boron, Copper, and Zinc Affect the Productivity, Cup Quality, and Chemical Compounds in Coffee Beans

Micronutrients perform specific and essential functions in plant metabolism, and their deficiency may lead to metabolic disturbances that affect coffee production and quality beverage. In Brazil, the B, Cu, and Zn are the main micronutrients, and these are provided by soil or foliar fertilization, frequently with low recovery efficiency. This work objected verifying the feasibility of supplying of B, Cu, and Zn via insertion of tablets in the orthotropic branch ofCoffea arabica, as well as to evaluate the coffee plant response in terms of productivity and quality of the beverage. Adult plants received B, Cu, and Zn, each micronutrient alone or combined with the other two, by foliar fertilization or by tablets inserted in the trunk base. The productivity, cupping quality, and some chemical indicators of beans quality were evaluated in two crop seasons. Boron, copper, and zinc supplied by foliar spray or solid injections in the trunk influenced the chemical composition and quality of the coffee beans, characterized by the cupping test and the levels of caffeine, trigonelline, sucrose, glucose, arabinose, mannose, 3-caffeoylquinic acid, 5-caffeoylquinic acid, polyphenol oxidase activity, and total phenolic compounds. Copper and zinc were equivalent in either form of supply regarding the production and quality of coffee.

Diurnal cycling of rhizosphere bacterial communities is associated with shifts in carbon metabolism

BackgroundThe circadian clock regulates plant metabolic functions and is an important component in plant health and productivity. Rhizosphere bacteria play critical roles in plant growth, health, and development and are shaped primarily by soil communities. Using Illumina next-generation sequencing and high-resolution mass spectrometry, we characterized bacterial communities of wild-type (Col-0) Arabidopsis thaliana and an acyclic line (OX34) ectopically expressing the circadian clock-associated cca1 transcription factor, relative to a soil control, to determine how cycling dynamics affected the microbial community. Microbial communities associated with Brachypodium distachyon (BD21) were also evaluated.ResultsSignificantly different bacterial community structures (P = 0.031) were observed in the rhizosphere of wild-type plants between light and dark cycle samples. Furthermore, 13% of the community showed cycling, with abundances of several families, including Burkholderiaceae, Rhodospirillaceae, Planctomycetaceae, and Gaiellaceae, exhibiting fluctuation in abundances relative to the light cycle. However, limited-to-no cycling was observed in the acyclic CCAox34 line or in soil controls. Significant cycling was also observed, to a lesser extent, in Brachypodium. Functional gene inference revealed that genes involved in carbohydrate metabolism were likely more abundant in near-dawn, dark samples. Additionally, the composition of organic matter in the rhizosphere showed a significant variation between dark and light cycles.ConclusionsThe results of this study suggest that the rhizosphere bacterial community is regulated, to some extent, by the circadian clock and is likely influenced by, and exerts influences, on plant metabolism and productivity. The timing of bacterial cycling in relation to that of Arabidopsis further suggests that diurnal dynamics influence plant-microbe carbon metabolism and exchange. Equally important, our results suggest that previous studies done without relevance to time of day may need to be reevaluated with regard to the impact of diurnal cycles on the rhizosphere microbial community.

Effect of root morphological traits on zinc efficiency in Iranian bread wheat genotypes

ABSTRACTZinc (Zn) has a vast number of functions in plant metabolism, the lack of which had dramatic effects on growth and yield of plants. Plants have morphological and biochemical responses to enhance mineral solubility in the soil and facilitate uptake, such as root plasticity, secretion processes and symbioses. Root architecture modification is an important plant response to nutrient availability. The aim of this study was to identify root morphological reactions to Zn efficiency in Iranian bread wheat genotypes. Soil and solution cultures were used to survey Zn efficiency. In soil culture, six and seven genotypes with high and low Zn contents were selected among 110 Iranian bread wheat genotypes, respectively. The solution culture experiments were set up in a completely randomized block design and plants fed with Johnson’s grass solution. All traits were assessed at 30 and 60 DAPs (days after planting). Our results showed a significant difference between two groups of efficient and inefficient genotypes only at 60 DAP, and Zn-efficient genotypes showed 1.63-, 1.50-, 1.69- and 1.92-fold increases in root diameter, surface area density, shoot and root dry weight, respectively, compared to inefficient genotypes. In contrast, Zn-inefficient genotypes had 1.20- and 2.62-fold more root length and fineness, respectively, than efficient genotypes. The positive significant correlations were observed between shoot and Zn uptake as well as root dry weight and Zn uptake at both stages. Furthermore, shoot and root dry weight showed a significant correlation with root fineness, diameter and surface area density at both stages. The path analysis showed indirect effects on Zn uptake through root traits. Our results showed that roots have a major role in Zn efficiency. Therefore, the better growth and greater Zn uptake in efficient genotypes, compared to inefficient ones, can be attributed to greater root diameter and surface area density, and lower root fineness in these genotypes.