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The symbiosis between legumes and nitrogen-fixing bacteria (rhizobia) is instrumental in sustaining the nitrogen cycle and providing fixed nitrogen to the food chain. Both partners must maintain an efficient nutrient exchange to ensure a successful symbiosis. This mini-review highlights the intricate phosphate and iron uptake and homeostasis processes taking place in legumes during their interactions with rhizobia. The coordination of transport and homeostasis of these nutrients in host plants and rhizobia ensures an efficient nitrogen fixation process and nutrient use. We discuss the genetic machinery controlling the uptake and homeostasis of these nutrients in the absence of rhizobia and under symbiotic conditions with this soil bacterium. We also highlight the genetic impact of the availability of phosphate and iron to coordinate the activation of the genetic programs that allow legumes to engage in symbiosis with rhizobia. Finally, we discuss how the transcription factor phosphate starvation response might be a crucial genetic element to integrate the plant's needs of nitrogen, iron and phosphate while interacting with rhizobia. Understanding the coordination of the iron and phosphate uptake and homeostasis can lead us to better harness the ecological benefits of the legume-rhizobia symbiosis, even under adverse environmental conditions. [ABSTRACT FROM AUTHOR]

Chromium (Cr) is an extremely toxic metal for all living organisms and its concentration in the environment is constantly increasing due to human activities. Plants quickly absorb Cr. Subsequently, it enters the human food chain and poses serious health risks. Chromium toxicity causes a significant reduction in plant growth by inducing oxidative damage and disturbing protein synthesis, enzyme activity, and nutrient uptake. Plants use diverse mechanisms to mitigate Cr toxicity; however, they are inadequate in the face of higher concentrations of Cr. Thus, it is essential to decrease Cr toxicity and increase the ability of plants to tolerate Cr stress. Nanoparticles (NPs) mitigate the toxicity of Cr by reducing its uptake and accumulation and improving antioxidant activities, nutrient homeostasis, photosynthetic efficiency, osmolyte synthesis, and hormonal balance. The complex interactions between NPs and microbes, signaling molecules, and hormones also significantly counter Cr toxicity. The present review discusses the various mechanisms of NPs for mitigating Cr toxicity. This review also addresses various research gaps to encourage the better utilization of NPs to mitigate Cr toxicity and improve crop growth and yield. This review offers new insights into the role of NPs in mitigating Cr toxicity. [ABSTRACT FROM AUTHOR]

Coating high concentrations of copper (Cu) on the inner wall of containers can efficiently inhibit root entanglement of container-grown seedlings. However, how the protective and defensive responses of roots maintain root structure and function during Cu-root pruning is still unclear. Here, Duranta erecta L. seedlings were planted in the containers coated with 40 (T1), 80 (T2), 100 (T3), 120 (T4), 140 (T5) and 160 (T6) g L−1 Cu(OH)2 with containers without Cu(OH)2 as the control. Although T5 and T6 produced the best inhibitory effect on root entanglement, root anatomy structure was damaged. T1 and T2 not only failed to completely control root circling, but also led to decreased root activity and stunted growth. Cu(OH)2 treatments significantly increased lignin concentration of roots with the highest values at T3 and T4. Compared with T3, seedlings at T4 had higher height, biomass and root activity, and no significant root entanglement. Excessive Cu accumulation in Cu(OH)2 treatments changed the absorption of other mineral nutrients and their allocation in the roots, stems and leaves. Overall, Ca was decreased while Mg, Mn, Fe and K were increased, especially K and Mn at T4 which is related to defense capacity. The results indicate that there is a Cu threshold to balance root entanglement control, defense capacity and nutrient uptake function under excessive Cu for container-grown D. erecta seedlings. [ABSTRACT FROM AUTHOR]

Plants are constantly challenged with numerous adverse environmental conditions, including biotic and abiotic stresses. Coordinated regulation of plant responses requires crosstalk between regulatory pathways initiated by different external cues. Stress induced by excessiveness or deficiency of nutrients has been shown to positively or negatively interact with pathogen-induced immune responses. Also, colonization by arbuscular mycorrhizal (AM) fungi can improve plant nutrition, mainly phosphorus and resistance to pathogen infection. The proposed review addresses these issues about a new question that integrates adaptation to nutrient stress and disease resistance. The main goal of the current review is to provide insights into the interconnected regulation between nutrient signaling and immune signaling pathways in rice, focusing on phosphate, potassium and iron signaling. The underpinnings of plant/pathogen/AM fungus interaction concerning rice/M. oryzae/R. irregularis is highlighted. The role of microRNAs (miRNAs) involved in Pi (miR399, miR827) and Fe (miR7695) homeostasis in pathogenic/symbiotic interactions in rice is discussed. The intracellular dynamics of membrane proteins that function in nutrient transport transgenic rice lines expressing fluorescent protein fusion genes are outlined. Integrating functional genomic, nutritional and metal content, molecular and cell biology approaches to understand how disease resistance is regulated by nutrient status leading to novel concepts in fundamental processes underlying plant disease resistance will help to devise novel strategies for crop protection with less input of pesticides and fertilizers. [ABSTRACT FROM AUTHOR]

Plant organ growth is controlled by various internal and external cues. However, the underlying molecular mechanisms that coordinate plant organ growth and nutrient homeostasis remain largely unknown. Recently, Zheng et al. identified the key regulators SOD7 (suppressor of da1-1) and GRF-INTERACTING FACTOR1 (GIF1) that control organ size and iron uptake in arabidopsis (Arabidopsis thaliana). Plant organ growth is controlled by various internal and external cues. However, the underlying molecular mechanisms that coordinate plant organ growth and nutrient homeostasis remain largely unknown. Recently, Zheng et al. identified the key regulators SOD7 (suppressor of da1-1) and GRF-INTERACTING FACTOR1 (GIF1) that control organ size and iron uptake in arabidopsis (Arabidopsis thaliana). [ABSTRACT FROM AUTHOR]

SUMMARY: Efficiently regulating growth to adapt to varying resource availability is crucial for organisms, including plants. In particular, the acquisition of essential nutrients is vital for plant development, as a shortage of just one nutrient can significantly decrease crop yield. However, plants constantly experience fluctuations in the presence of multiple essential mineral nutrients, leading to combined nutrient stress conditions. Unfortunately, our understanding of how plants perceive and respond to these multiple stresses remains limited. Unlocking this mystery could provide valuable insights and help enhance plant nutrition strategies. This review focuses specifically on the regulation of phosphorous homeostasis in plants, with a primary emphasis on recent studies that have shed light on the intricate interactions between phosphorous and other essential elements, such as nitrogen, iron, and zinc, as well as non‐essential elements like aluminum and sodium. By summarizing and consolidating these findings, this review aims to contribute to a better understanding of how plants respond to and cope with combined nutrient stress. Significance Statement: Plant growth, resource adaptation, and nutrient acquisition are crucial. Combined nutrient stress from fluctuating mineral levels is challenging. Our understanding of plant responses is limited. This review emphasizes phosphorus homeostasis, and recent research on element interactions, aiming to enhance plant nutrition under combined stress. [ABSTRACT FROM AUTHOR]

The hypothalamus is a key integrating center that is involved in the initiation of the corticosteroid stress response, and in regulating nutrient homeostasis. Although cortisol, the principal glucocorticoid in humans and teleosts, plays a central role in feeding regulation, the mechanisms are far from clear. We tested the hypothesis that the metabolic changes to cortisol exposure signal an energy excess in the hypothalamus, leading to feeding suppression during stress in fish. Rainbow trout (Oncorhynchus mykiss) were administered a slow-release cortisol implant for 3 days, and the metabolite profiles in the plasma, hypothalamus, and the rest of the brain were assessed. Also, U-13C-glucose was injected into the hypothalamus by intracerebroventricular (ICV) route, and the metabolic fate of this energy substrate was followed in the brain regions by metabolomics. Chronic cortisol treatment reduced feed intake, and this corresponded with a downregulation of the orexigenic gene agrp, and an upregulation of the anorexigenic gene cart in the hypothalamus. The U-13C-glucose-mediated metabolite profiling indicated an enhancement of glycolytic flux and tricarboxylic acid intermediates in the rest of the brain compared with the hypothalamus. There was no effect of cortisol treatment on the phosphorylation status of AMPK or mechanistic target of rapamycin in the brain, whereas several endogenous metabolites, including leucine, citrate, and lactate were enriched in the hypothalamus, suggesting a tissue-specific metabolic shift in response to cortisol stimulation. Altogether, our results suggest that the hypothalamus-specific enrichment of leucine and the metabolic fate of this amino acid, including the generation of lipid intermediates, contribute to cortisol-mediated feeding suppression in fish. [ABSTRACT FROM AUTHOR]

Salicylic acid (SA) has emerged as an excellent phyto-hormone to improve stress tolerance in plants. However, no information is available about the role of SA under combined SS and HS. Therefore, this study was performed to underpin the potential role of SA to mitigate SS and HS in wheat crop. The study was comprised of different treatments: control, SS (8 dS m-1), HS (imposed at flag leaf stage) and combination of SS (8 dS m-1) and HS and different levels of SA: control, 50 mM, 100 mM and 150 mM. Salinity and HS substantially decreased the growth, and yield traits of wheat that was linked with increased electrolyte leakage (EL), malondialdehyde (MDA) and hdrogen peroxid (H2O2) production, sodium (Na+) and chloride (Cl-) accumulation and decrease in relative water contents (RWC), photosynthetic pigments, total soluble proteins (TSP) and free amino acids (FAA) accumulation and nutrient uptake. Nonetheless, foliar applied SA particularly 150 mM appreciably improved the growth and yield of wheat crop by increasing RWC, antioxidant activity soluble sugars, proline, TSP, FAA accumulation, nutrient uptake and decreasing EL, electrolyte leakage, MDA and H2O2 and restricting the entry of toxic ions. Therefore, these findings suggested that SA could improve the growth and yield of wheat under SS and HS stresses by improving physiological activity, photosynthetic pigments, antioxidant activity and accumulation of osmolytes. [ABSTRACT FROM AUTHOR]

Soil salinization has increased over recent years and is negatively affecting crop productivity. Nutrient application is an effective strategy to improve abiotic stress tolerance in crops. The application of coated fertilizers has emerged as an excellent approach to mitigate the adverse impacts of soil salinity. Therefore, the present study was conducted to determine the effects of zinc and sulfur coated urea on the performance of wheat growing under saline conditions. The study comprised of diverse salinity stress levels; 0, 6 and 12 dS m-1, cross combined with normal urea (NU), zinc coated urea (ZCU) and sulfur coated urea (SCU). Salinity stress reduced wheat yield by impairing leaf water status, reducing photosynthetic pigments, osmolytes accumulation, potassium (K) and nitrogen (N) uptake while increasing sodium (Na) and chloride (Cl) uptake and hydrogen peroxide (H2O2), malondialdehyde (MDA) and electrolyte leakage (EL) accumulation. The application of ZCU increased the wheat yield by enhancing photosynthetic pigments, leaf water status, antioxidant activities, osmolytes accumulation, and reducing H2O2, MDA and EL accumulation. Furthermore, the significant increase in growth and yield of wheat with ZCU and SCU was also linked with improved K and N uptake, higher nitrogen use efficiency (NUE) and reduced Na and Cl concentration. Thus, the application of ZCU could be an effective approach to improve wheat productivity under saline conditions.

Cadmium (Cd) is one of the most toxic elements in soil, affecting morphological, physiological, and biochemical processes in plants. Mineral plant nutrition was tested as an effective approach to mitigate Cd stress in several crop species. In this regard, the present study aimed to elucidate how different phosphorus (P) fertilization regimes can improve some bio-physiological processes in tomato plants exposed to Cd stress. In a hydroponic experiment, the impact of two phosphorus fertilizer forms (Polyphosphate (poly-P): condensed P-form with 100% polymerization rate and orthophosphate (ortho-P): from orthophosphoric acid) on the photosynthetic activity, plant growth, and nutrient uptake was assessed under three levels of Cd stress (0, 12, and 25 µM of CdCl2). The obtained results confirmed the negative effects of Cd stress on the chlorophyll content and the efficiency of the photosynthesis machinery. The application of poly-P fertilizer significantly improved the chlorophyll stability index (82%) under medium Cd stress (Cd12), as compared to the ortho-P form (55%). The analysis of the chlorophyll α fluorescence transient curve revealed that the amplitude of Cd effect on the different steps of electron transfer between PSII and PSI was significantly reduced under the poly-P fertilization regime compared to ortho-P, especially under Cd12. The evaluation of the RE0/RC parameter showed that the electron flux reducing end electron acceptors at the PSI acceptor side per reaction center was significantly improved in the poly-P treatment by 42% under Cd12 compared to the ortho-P treatment. Moreover, the use of poly-P fertilizer enhanced iron uptake and its stoichiometric homeostasis in the shoot tissue which maintained an adequate absorption of iron under Cd stress conditions. Findings from this study revealed for the first time that inorganic polyphosphate fertilizers can reduce Cd toxicity in tomato plants by enhancing photosynthesis activity, nutrient uptake, plant growth, and biomass accumulation despite the high level of cadmium accumulation in shoot tissues.

Salinity stress is serious threat to crop productivity and globe food security. This study investigated the impact of NaCl (neutral salt) and basic salt (basic salt) on seed germination physiological and biochemical traits of Amorpha fruticosa. Salt stress had no significant effect on seed germination rate, however, alkali stress significantly decreased (p≤0.05) rate of germination. Both stresses also negatively affected the growth of radicle and germination (P

Macroautophagy/autophagy is a highly conserved catabolic process vital for cellular stress responses and maintaining equilibrium within the cell. Malfunctioning autophagy has been implicated in the pathogenesis of various diseases, including certain neurodegenerative disorders, diabetes, metabolic diseases, and cancer. Cells face diverse metabolic challenges, such as limitations in nitrogen, carbon, and minerals such as phosphate and iron, necessitating the integration of complex metabolic information. Cells utilize a signal transduction network of sensors, transducers, and effectors to coordinate the execution of the autophagic response, concomitant with the severity of the nutrient‐starvation condition. This review presents the current mechanistic understanding of how cells regulate the initiation of autophagy through various nutrient‐dependent signaling pathways. Emphasizing findings from studies in yeast, we explore the emerging principles that underlie the nutrient‐dependent regulation of autophagy, significantly shaping stress‐induced autophagy responses under various metabolic stress conditions. [ABSTRACT FROM AUTHOR]

Soil salinization has increased over recent years and is negatively affecting crop productivity. Nutrient application is an effective strategy to improve abiotic stress tolerance in crops. The application of coated fertilizers has emerged as an excellent approach to mitigate the adverse impacts of soil salinity. Therefore, the present study was conducted to determine the effects of zinc and sulfur coated urea on the performance of wheat growing under saline conditions. The study comprised of diverse salinity stress levels; 0, 6 and 12 dS m-1, cross combined with normal urea (NU), zinc coated urea (ZCU) and sulfur coated urea (SCU). Salinity stress reduced wheat yield by impairing leaf water status, reducing photosynthetic pigments, osmolytes accumulation, potassium (K) and nitrogen (N) uptake while increasing sodium (Na) and chloride (Cl) uptake and hydrogen peroxide (H2O2), malondialdehyde (MDA) and electrolyte leakage (EL) accumulation. The application of ZCU increased the wheat yield by enhancing photosynthetic pigments, leaf water status, antioxidant activities, osmolytes accumulation, and reducing H2O2, MDA and EL accumulation. Furthermore, the significant increase in growth and yield of wheat with ZCU and SCU was also linked with improved K and N uptake, higher nitrogen use efficiency (NUE) and reduced Na and Cl concentration. Thus, the application of ZCU could be an effective approach to improve wheat productivity under saline conditions. [ABSTRACT FROM AUTHOR]

Alternative splicing (AS) is a gene regulatory mechanism modulating gene expression in multiple ways. AS is prevalent in all eukaryotes including plants. AS generates two or more mRNAs from the precursor mRNA (pre-mRNA) to regulate transcriptome complexity and proteome diversity. Advances in next-generation sequencing, omics technology, bioinformatics tools, and computational methods provide new opportunities to quantify and visualize AS-based quantitative trait variation associated with plant growth, development, reproduction, and stress tolerance. Domestication, polyploidization, and environmental perturbation may evolve novel splicing variants associated with agronomically beneficial traits. To date, pre-mRNAs from many genes are spliced into multiple transcripts that cause phenotypic variation for complex traits, both in model plant Arabidopsis and field crops. Cataloguing and exploiting such variation may provide new paths to enhance climate resilience, resource-use efficiency, productivity, and nutritional quality of staple food crops. This review provides insights into AS variation alongside a gene expression analysis to select for novel phenotypic diversity for use in breeding programs. AS contributes to heterosis, enhances plant symbiosis (mycorrhiza and rhizobium), and provides a mechanistic link between the core clock genes and diverse environmental clues. [ABSTRACT FROM AUTHOR]

Plant growth and development depend on sufficient nutrient availability in soils. Agricultural soils are generally nitrogen (N) deficient, and thus soils need to be supplemented with fertilizers. Ammonium (NH4+) is a major inorganic N source. However, at high concentrations, NH4+ becomes a stressor that inhibits plant growth. The cause of NH4+ stress or toxicity is multifactorial, but the interaction of NH4+ with other nutrients is among the main determinants of plants' sensitivity towards high NH4+ supply. In addition, NH4+ uptake and assimilation provoke the acidification of the cell external medium (apoplast/rhizosphere), which has a clear impact on nutrient availability. This review summarizes current knowledge, at both the physiological and the molecular level, of the interaction of NH4+ nutrition with essential mineral elements that are absorbed as cations, both macronutrients (K+, Ca2+, Mg2+) and micronutrients (Fe2+/3+, Mn2+, Cu+/2+, Zn2+, Ni2+). We hypothesize that considering these nutritional interactions, and soil pH, when formulating fertilizers may be key in order to boost the use of NH4+-based fertilizers, which have less environmental impact compared with nitrate-based ones. In addition, we are convinced that better understanding of these interactions will help to identify novel targets with the potential to improve crop productivity. [ABSTRACT FROM AUTHOR]

Ionomics and transcriptomics were applied to demonstrate response of rice to arsenite [As(III)] stress in the current study. Rice plants were cultured in nutrient solutions treated with 0, 100 and 500 μg/L As(III) coded as CK, As1 and As5, respectively. The rice ionomes exhibited discriminatory response to environmental disturbances. Solid evidence of the effects of As(III) stress on binding, transport or metabolism of P, K, Ca, Zn and Cu was obtained in this work. Differentially expressed genes (DEGs) in the shoots were identified in three datasets: As1 vs CK, As5 vs CK and As5 vs As1. DEGs identified simultaneously in two or three datasets were selected for subsequent interaction and enrichment analyses. Upregulation of genes involved in protein kinase activity, phosphorus metabolic process and phosphorylation were detected in the rice treated with As(III), resulting in the maintenance of P homeostasis in the shoots. Zn and Ca binding genes were up-regulated since excess As inhibited the translocation of Zn and Ca from roots to shoots. Increased expression of responsive genes including HMA, WRKY, NAC and PUB genes conferred As tolerance in the rice plants to cope with external As(III) stress. The results suggested that As(III) stress could disturb the uptake and translocation of macro and essential elements by rice. Plants could regulate the expression of corresponding genes to maintain mineral nutrient homeostasis for essential metabolic processes. [ABSTRACT FROM AUTHOR]

Natural variation among individuals and populations exists in all species, playing key roles in response to environmental stress and adaptation. Micro- and macronutrients have a wide range of functions in photosynthetic organisms, and mineral nutrition thus plays a sizable role in biomass production. To maintain nutrient concentrations inside the cell within physiological limits and prevent the detrimental effects of deficiency or excess, complex homeostatic networks have evolved in photosynthetic cells. The microalga Chlamydomonas reinhardtii (Chlamydomonas) is a unicellular eukaryotic model for studying such mechanisms. In this work, 24 Chlamydomonas strains, comprising field isolates and laboratory strains, were examined for intraspecific differences in nutrient homeostasis. Growth and mineral content were quantified in mixotrophy, as full nutrition control, and compared with autotrophy and nine deficiency conditions for macronutrients (–Ca, –Mg, –N, –P, and –S) and micronutrients (–Cu, –Fe, –Mn, and –Zn). Growth differences among strains were relatively limited. However, similar growth was accompanied by highly divergent mineral accumulation among strains. The expression of nutrient status marker genes and photosynthesis were scored in pairs of contrasting field strains, revealing distinct transcriptional regulation and nutrient requirements. Leveraging this natural variation should enable a better understanding of nutrient homeostasis in Chlamydomonas. [ABSTRACT FROM AUTHOR]

Modern agriculture is facing the challenges of salinity and heat stresses, which pose a serious threat to crop productivity and global food security. Thus, it is necessary to develop the appropriate measures to minimize the impacts of these serious stresses on field crops. Silicon (Si) is the second most abundant element on earth and has been recognized as an important substance to mitigate the adverse effects of abiotic stresses. Thus, the present study determined the role of Si in mitigating adverse impacts of salinity stress (SS) and heat stress (HS) on wheat crop. This study examined response of different wheat genotypes, namely Akbar-2019, Subhani-2021, and Faisalabad-2008, under different treatments: control, SS (8 dSm−1), HS, SS + HS, control + Si, SS + Si, HS+ Si, and SS + HS+ Si. This study's findings reveal that HS and SS caused a significant decrease in the growth and yield of wheat by increasing electrolyte leakage (EL), malondialdehyde (MDA), and hydrogen peroxide (H2O2) production; sodium (Na+) and chloride (Cl−) accumulation; and decreasing relative water content (RWC), chlorophyll and carotenoid content, total soluble proteins (TSP), and free amino acids (FAA), as well as nutrient uptake (potassium, K; calcium, Ca; and magnesium, Mg). However, Si application offsets the negative effects of both salinity and HS and improved the growth and yield of wheat by increasing chlorophyll and carotenoid contents, RWC, antioxidant activity, TSP, FAA accumulation, and nutrient uptake (Ca, K, and Mg); decreasing EL, electrolyte leakage, MDA, and H2O2; and restricting the uptake of Na+ and Cl−. Thus, the application of Si could be an important approach to improve wheat growth and yield under normal and combined saline and HS conditions by improving plant physiological functioning, antioxidant activities, nutrient homeostasis, and osmolyte accumulation. [ABSTRACT FROM AUTHOR]

The high concentration of bicarbonate ion (HCO3-) in irrigation water or soil is a limiting factor for the growth and production of kiwifruit vineyards. Especially the high concentration of bicarbonate in irrigation water can cause negative effects on the development of many plants at different rates. In this study, the effects of different concentrations (0, 170, 350, and 550 mg L-1) of bicarbonate ion (HCO3-) in irrigation water on six kiwifruit seedlings (DA1, DA2, CK1, CK2, CK3, AA) were studied in the greenhouse condition. The six kiwifruit seedlings used in the study belong to a total of 3 different species (A. deliciosa, A. chinensis, and A. arguta) and also have different ploidy levels (2n, 4n, and 6n). The highest (16.6%) leaf abscission was found in AA (A. arguta) seedlings when exposed to HCO3- stress, and the lowest value (1.19%) was found in DA1 (A. deliciosa cv. 'Bruno') seedlings. Depending on the cultivar or species, bicarbonate caused leaf chlorosis at different rates in kiwifruit seedlings. CK1 (A. chinensis) seedlings showed the highest (38.46%) leaf chlorosis and DA2 (A. deliciosa) seedlings showed the lowest (6.95%) leaf chlorosis. Bicarbonate reduced chlorophylls and carotenoid content in all kiwifruit genotypes. Furthermore, it induced leaf iron (Fe), manganese (Mn), and zinc (Zn) deficiency. Seedlings of 'Bruno' showed the lowest decline of leaf iron (Fe) and Zinc (Zn) content when exposed to HCO3- stress. In contrast, a high level of Manganese (Mn) was found in seedlings of CK3. Overall, it was detected a close relationship between bicarbonate stress and nutrient homeostasis in different kiwifruit genotypes. [ABSTRACT FROM AUTHOR]

Aims: Drought stress is one of the most limiting factors for agriculture and ecosystem productivity. Climate change exacerbates this threat by inducing increasingly intense and frequent drought events. Root plasticity during both drought and post-drought recovery is regarded as fundamental to understanding plant climate resilience and maximizing production. We mapped the different research areas and trends that focus on the role of roots in plant response to drought and rewatering and asked if important topics were overlooked. Methods: We performed a comprehensive bibliometric analysis based on journal articles indexed in the Web of Science platform from 1900-2022. We evaluated a) research areas and temporal evolution of keyword frequencies, b) temporal evolution and scientific mapping of the outputs over time, c) trends in the research topics analysis, d) marked journals and citation analysis, and e) competitive countries and dominant institutions to understand the temporal trends of root plasticity during both drought and recovery in the past 120 years. Results: Plant physiological factors, especially in the aboveground part (such as "photosynthesis", "gas-exchange", "abscisic-acid") in model plants Arabidopsis, crops such as wheat and maize, and trees were found to be the most popular study areas; they were also combined with other abiotic factors such as salinity, nitrogen, and climate change, while dynamic root growth and root system architecture responses received less attention. Co-occurrence network analysis showed that three clusters were classified for the keywords including 1) photosynthesis response; 2) physiological traits tolerance (e.g. abscisic acid); 3) root hydraulic transport. Thematically, themes evolved from classical agricultural and ecological research via molecular physiology to root plasticity during drought and recovery. The most productive (number of publications) and cited countries and institutions were situated on drylands in the USA, China, and Australia. In the past decades, scientists approached the topic mostly from a soilplant hydraulic perspective and strongly focused on aboveground physiological regulation, whereas the actual belowground processes seemed to have been the elephant in the room. There is a strong need for better investigation into root and rhizosphere traits during drought and recovery using novel root phenotyping methods and mathematical modeling. [ABSTRACT FROM AUTHOR]

Salinity and waterlogging stresses have catastrophic effects on plants. Physiological and molecular mechanisms of plant responses to individual salinity and waterlogging stresses have been widely investigated. Several research studies have been conducted to understand the combined effects of salinity and waterlogging on plant growth, photosynthesis, and mineral homeostasis, but no systematic review has been performed yet to comprehend the cumulative effects of salinity and waterlogging on plants. This work employed a systematic approach to examine how plants respond to combined salinity and waterlogging stress compared to individual stresses, and to identify potential research gaps in this field. Our analysis indicates that combined salinity and waterlogging stress inhibits growth processes more strongly than salinity or waterlogging stress alone. In addition, the combined effect of salinity and waterlogging on photosynthesis and ionic homeostasis is greater than the sum of the individual effect of each. Our analysis further implies that tolerance to combined salinity and waterlogging stress is mostly determined by salinity tolerance. An examination of subgroups found that hydrophytes are more vulnerable to combined salinity and waterlogging than halophytes. We identified several research gaps that should be addressed in future research to enhance plant salinity and waterlogging stress tolerance.

While the individual influences of melatonin (MT) and polyamines (PAs) have been widely studied under various abiotic stresses, little is known about their interaction under salinity stress. In the present study, salt stress applied by 50 mM of sodium chloride (NaCl) on snap bean seedlings has been supplemented with 20 μM of MT and/or 100 μM of putrescine (Put) (individually and in combination). The results indicated that under salinity stress, the combination of MT + Put achieved the highest significant increase in shoot fresh and dry weight, chlorophyll (Chl a), Chl a + b, carotenoids, total soluble sugars, proline, K, Ca, and cell membrane stability index (CMSI), as well as catalase (CAT) and peroxidase (POX) activities. This improvement was associated with an obvious decrease in Na, Na/K ratio, and oxidative damage as indicated by reducing leaf contents of methylglyoxal (MG), hydrogen peroxide (H2O2), and the rate of lipid peroxidation (malondialdehyde; MDA). Moreover, the combination of MT + Put demonstrated a significant decrease in the activities of diamine oxidase (DAO) and polyamine oxidase (PAO) leading to the reduction of the rate of polyamine oxidation. Meanwhile, MT applied individually gave the highest significant increase in leaf relative water content (RWC), Chl b, superoxide dismutase (SOD), and ascorbate peroxidase (APX). Conclusively, the combination treatment of MT + Put could decrease the degradation of polyamines and enhance tolerance to salinity stress in snap bean seedlings. [ABSTRACT FROM AUTHOR]

During their lifespan, sessile plants have to cope with bioavailability of the suboptimal nutrient concentration and have to constantly sense/evolve the connecting web of signal cascades for efficient nutrient uptake, storage, and translocation for proper growth and metabolism. However, environmental fluctuations and escalating anthropogenic activities are making it a formidable challenge for plants. This is adding to (micro)nutrient-deficient crops and nutritional insecurity. Biofortification is emerging as a sustainable and efficacious approach which can be utilized to combat the micronutrient malnutrition. A biofortified crop has an enriched level of desired nutrients developed using conventional breeding, agronomic practices, or advanced biotechnological tools. Nutrient homeostasis gets hampered under nutrient stress, which involves disturbance in short-distance and long-distance cell–cell/cell-organ communications involving multiple cellular and molecular components. Advanced sequencing platforms coupled with bioinformatics pipelines and databases have suggested the potential roles of tiny signaling molecules and post-transcriptional regulators, the microRNAs (miRNAs) in key plant phenomena including nutrient homeostasis. miRNAs are seen as emerging targets for biotechnology-based biofortification programs. Thus, understanding the mechanistic insights and regulatory role of miRNAs could open new windows for exploring them in developing nutrient-efficient biofortified crops. This review discusses significance and roles of miRNAs in plant nutrition and nutrient homeostasis and how they play key roles in plant responses to nutrient imbalances/deficiencies/toxicities covering major nutrients—nitrogen (N), phosphorus (P), sulfur (S), magnesium (Mg), iron (Fe), and zinc (Zn). A perspective view has been given on developing miRNA-engineered biofortified crops with recent success stories. Current challenges and future strategies have also been discussed. [ABSTRACT FROM AUTHOR]

Plants engage in symbiotic relationships with soil microorganisms to overcome nutrient limitations in their environment. Among the best studied endosymbiotic interactions in plants are those with arbuscular mycorrhizal (AM) fungi and N-fixing bacteria called rhizobia. The mechanisms regulating plant nutrient homeostasis and acquisition involve small mobile molecules such as peptides and micro RNAs (miRNAs). A large number of CLE (CLAVATA3/EMBRYO SURROUNDING REGION-RELATED) and CEP (C-TERMINALLY ENCODED PEPTIDE) peptide hormones as well as certain miRNAs have been reported to differentially respond to the availability of essential nutrients such as nitrogen (N) and phosphorus (P). Interestingly, a partially overlapping pool of these molecules is involved in plant responses to root colonization by rhizobia and AM fungi, as well as mineral nutrition. The crosstalk between root endosymbiosis and nutrient availability has been subject of intense investigations, and new insights in locally or systemically mobile molecules in nutrient- as well as symbiosis-related signaling continue to arise. Focusing on the key roles of peptides and miRNAs, we review the mechanisms that shape plant responses to nutrient limitation and regulate the establishment of symbiotic associations with beneficial soil microorganisms. [ABSTRACT FROM AUTHOR]

The phytohormone cytokinin is implicated in a range of growth, developmental, and defense processes. A growing body of evidence supports a crosstalk between cytokinin and nutrient signaling pathways, such as nitrate availability. Cytokinin signaling regulates sulfur-responsive gene expression, but the underlying molecular mechanisms and their impact on sulfur-containing metabolites have not been systematically explored. Using a combination of genetic and pharmacological tools, we investigated the interplay between cytokinin signaling and sulfur homeostasis. Exogenous cytokinin triggered sulfur starvation-like gene expression accompanied by a decrease in sulfate and glutathione content. This process was uncoupled from the activity of the major transcriptional regulator of sulfate starvation signaling SULFUR LIMITATION 1 and an important glutathione-degrading enzyme, γ-glutamyl cyclotransferase 2;1, expression of which was robustly up-regulated by cytokinin. Conversely, glutathione accumulation was observed in mutants lacking the cytokinin receptor ARABIDOPSIS HISTIDINE KINASE 3 and in cytokinin-deficient plants. Cytokinin-deficient plants displayed improved root growth upon exposure to glutathione-depleting chemicals which was attributed to a higher capacity to maintain glutathione levels. These results shed new light on the interplay between cytokinin signaling and sulfur homeostasis. They position cytokinin as an important modulator of sulfur uptake, assimilation, and remobilization in plant defense against xenobiotics and root growth. [ABSTRACT FROM AUTHOR]

Symbiotic nitrogen fixation is an important component in the nitrogen cycle and is a potential solution for sustainable agriculture. It is the result of the interactions between the plant host, mostly restricted to legume species, and the rhizobial symbiont. From the first encounter between the host and the symbiont to eventual successful nitrogen fixation, there are delicate processes involved, such as nodule organogenesis, rhizobial infection thread progression, differentiation of the bacteroid, deregulation of the host defense systems, and reallocation of resources. All these processes are tightly regulated at different levels. Recent evidence revealed that non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), participate in these processes by controlling the transcription and translation of effector genes. In general, ncRNAs are functional transcripts without translation potential and are important gene regulators. MiRNAs, negative gene regulators, bind to the target mRNAs and repress protein production by causing the cleavage of mRNA and translational silencing. LncRNAs affect the formation of chromosomal loops, DNA methylation, histone modification, and alternative splicing to modulate gene expression. Both lncRNAs and circRNAs could serve as target mimics of miRNA to inhibit miRNA functions. In this review, we summarized and discussed the current understanding of the roles of ncRNAs in legume nodulation and nitrogen fixation in the root nodule, mainly focusing on their regulation of hormone signal transduction, the autoregulation of nodulation (AON) pathway and nutrient homeostasis in nodules. Unraveling the mediation of legume nodulation by ncRNAs will give us new insights into designing higher-performance leguminous crops for sustainable agriculture. [ABSTRACT FROM AUTHOR]

Proline plays adaptive roles in plant tolerance to cadmium (Cd)-induced stress, but many gaps remain to be elucidated as the responses triggered by exogenously supplied proline or endogenously overproduction are not well known. Thus, we assayed the nutritional status, metabolite profiling, and antioxidative responses in wild type and transgenic tobacco (Nicotiana tabacum L.) containing the P5CSF129A gene under control of the cauliflower mosaic virus (CaMV35S) or stress inducible rd29A promoters. The plants were exposed or unexposed to Cd (0 and 50 μmol L−1 CdCl2·H2O) for 24 and 72 h. The wild type plants were also treated with or without exogenous proline (1 mmol L−1). Plants supplied with exogenous proline exhibited lower Cd translocation from roots to leaves than plants overproducing proline, avoiding oxidative damages in the leaves of these plants. Meanwhile, tobacco overproducing proline was less susceptible to Cd-induced nutritional changes than wild type plants and presented better metabolic adjustment under Cd exposure compared to plants supplied with exogenous proline. Plants overproducing proline increased the synthesis of sugars and organic acids under Cd exposure, which contributed to absence of oxidative stress, since both superoxide dismutase and catalase were not active against Cd-induced oxidative stress in these genotypes. Plants overproducing proline under the control of rd29A presented higher proline concentration in comparison to the CaMV35S promoter. With exception of rd29A plants that presented high proline and reduced glutathione (GSH) concentrations, the other plants presented an inverse correlation between proline and GSH synthesis after 72 h of Cd exposure. [ABSTRACT FROM AUTHOR]

MePMTR1 and ZmPMTR1 are membrane proteins that show a high affinity for melatonin binding and are required for melatonin-mediated drought resistance and alleviation of darkness-induced leaf senescence and stomatal closure. Identification of melatonin in plants and its effects on plasma melatonin levels and binding to melatonin receptors in vertebrates. PP2C1 fine-tunes melatonin biosynthesis and phytomelatonin receptor PMTR1 binding to melatonin in cassava. Keywords: Phytomelatonin; phytohormone; signaling pathways; metabolism; nutrient homeostasis; stress resistance EN Phytomelatonin phytohormone signaling pathways metabolism nutrient homeostasis stress resistance 5773 5778 6 10/04/22 20220930 NES 220930 Melatonin ( I N i -acetyl-5-methoxytryptamine) synthesized by plants is known as phytomelatonin. [Extracted from the article]

Plants engage in mutually beneficial relationships with microbes, such as arbuscular mycorrhizal fungi or nitrogen-fixing rhizobia, for optimized nutrient acquisition. In return, the microbial symbionts receive photosynthetic carbon from the plant. Both symbioses are regulated by the plant nutrient status, indicating the existence of signaling pathways that allow the host to fine-tune its interactions with the beneficial microbes depending on its nutrient requirements. Peptide hormones coordinate a plethora of developmental and physiological processes and, recently, various peptide families have gained special attention as systemic and local regulators of plant–microbe interactions and nutrient homeostasis. In this review, we identify five 'rules' or guiding principles that govern peptide function during symbiotic plant–microbe interactions, and highlight possible points of integration with nutrient acquisition pathways. Plant interactions with arbuscular mycorrhizal fungi, beneficial soil bacteria, and nutrient homeostasis are optimized by an interconnected network of peptide signals. Symbiosis-regulating signaling peptides are members of large protein families, often with a variety of functions in plant physiology and development. The mechanism of peptide-signaling specificity in the context of plant–microbe interactions, nutrient homeostasis, and cross-kingdom peptide mimicry involves antagonism and coordination between individual peptide signals. Although many of the symbiosis-associated peptide signaling pathways converge at common downstream signaling hubs and intersect with phytohormone signaling, the signaling outcomes are, at least partially, unique. [ABSTRACT FROM AUTHOR]

Modern agriculture is facing the challenges of salinity and heat stresses, which pose a serious threat to crop productivity and global food security. Thus, it is necessary to develop the appropriate measures to minimize the impacts of these serious stresses on field crops. Silicon (Si) is the second most abundant element on earth and has been recognized as an important substance to mitigate the adverse effects of abiotic stresses. Thus, the present study determined the role of Si in mitigating adverse impacts of salinity stress (SS) and heat stress (HS) on wheat crop. This study examined response of different wheat genotypes, namely Akbar-2019, Subhani-2021, and Faisalabad-2008, under different treatments: control, SS (8 dSm−1), HS, SS + HS, control + Si, SS + Si, HS+ Si, and SS + HS+ Si. This study’s findings reveal that HS and SS caused a significant decrease in the growth and yield of wheat by increasing electrolyte leakage (EL), malondialdehyde (MDA), and hydrogen peroxide (H2O2) production; sodium (Na+) and chloride (Cl−) accumulation; and decreasing relative water content (RWC), chlorophyll and carotenoid content, total soluble proteins (TSP), and free amino acids (FAA), as well as nutrient uptake (potassium, K; calcium, Ca; and magnesium, Mg). However, Si application offsets the negative effects of both salinity and HS and improved the growth and yield of wheat by increasing chlorophyll and carotenoid contents, RWC, antioxidant activity, TSP, FAA accumulation, and nutrient uptake (Ca, K, and Mg); decreasing EL, electrolyte leakage, MDA, and H2O2; and restricting the uptake of Na+ and Cl−. Thus, the application of Si could be an important approach to improve wheat growth and yield under normal and combined saline and HS conditions by improving plant physiological functioning, antioxidant activities, nutrient homeostasis, and osmolyte accumulation.

Main conclusion: This minireview details the impact of iron–phosphate and zinc–phosphate interactions in plants and provides perspectives for further areas of research regarding nutrient homeostasis. Iron (Fe) and zinc (Zn) are among the most important micronutrients for plant growth and have numerous implications for human health and agriculture. While plants have developed efficient uptake and transport mechanisms for Fe and Zn, emerging research has shown that the availability of other nutrients in the environment influences the homeostasis of Fe and Zn within plants. In this minireview, we present the current knowledge regarding homeostatic interactions of Fe and Zn with the macronutrient phosphorous (P) and the resulting physiological responses to combined deficiencies of these nutrients. Fe and P interactions have been shown to influence root development, photosynthesis, and biological processes aiding Fe uptake. Zn and P interactions also influence root growth, and coordination of Zn-dependent transcriptional regulation contributes to phosphate (Pi) transport in the plant. Understanding homeostatic interactions among these different nutrients is of critical importance to obtain a more complete understanding of plant nutrition in complex soil environments. [ABSTRACT FROM AUTHOR]

Salinity is a global conundrum that negatively affects various biometrics of agricultural crops. Jasmonic acid (JA) is a phytohormone that reinforces multilayered defense strategies against abiotic stress, including salinity. This study investigated the effect of JA (60 μM) on two wheat cultivars, namely ZM9 and YM25, exposed to NaCl (14.50 dSm−1) during two consecutive growing seasons. Morphologically, plants primed with JA enhanced the vegetative growth and yield components. The improvement of growth by JA priming is associated with increased photosynthetic pigments, stomatal conductance, intercellular CO2, maximal photosystem II efficiency, and transpiration rate of the stressed plants. Furthermore, wheat cultivars primed with JA showed a reduction in the swelling of the chloroplast, recovery of the disintegrated thylakoids grana, and increased plastoglobuli numbers compared to saline-treated plants. JA prevented dehydration of leaves by increasing relative water content and water use efficiency via reducing water and osmotic potential using proline as an osmoticum. There was a reduction in sodium (Na+) and increased potassium (K+) contents, indicating a significant role of JA priming in ionic homeostasis, which was associated with induction of the transporters, viz., SOS1, NHX2, and HVP1. Exogenously applied JA mitigated the inhibitory effect of salt stress in plants by increasing the endogenous levels of cytokinins and indole acetic acid, and reducing the abscisic acid (ABA) contents. In addition, the oxidative stress caused by increasing hydrogen peroxide in salt-stressed plants was restrained by JA, which was associated with increased α-tocopherol, phenolics, and flavonoids levels and triggered the activities of superoxide dismutase and ascorbate peroxidase activity. This increase in phenolics and flavonoids could be explained by the induction of phenylalanine ammonia-lyase activity. The results suggest that JA plays a key role at the morphological, biochemical, and genetic levels of stressed and non-stressed wheat plants which is reflected in yield attributes. Hierarchical cluster analysis and principal component analyses showed that salt sensitivity was associated with the increments of Na+, hydrogen peroxide, and ABA contents. The regulatory role of JA under salinity stress was interlinked with increased JA level which consequentially improved ion transporting, osmoregulation, and antioxidant defense.

Durum wheat is one of the most important agricultural crops, currently providing 18% of the daily intake of calories and 20% of daily protein intake for humans. However, being wheat that is cultivated in arid and semiarid areas, its productivity is threatened by drought stress, which is being exacerbated by climate change. Therefore, the identification of drought tolerant wheat genotypes is critical for increasing grain yield and also improving the capability of crops to uptake and assimilate nutrients, which are seriously affected by drought. This work aimed to determine the effect of arbuscular mycorrhizal fungi (AMF) on plant growth under normal and limited water availability in two durum wheat genotypes (Svevo and Etrusco). Furthermore, we investigated how the plant nutritional status responds to drought stress. We found that the response of Svevo and Etrusco to drought stress was differentially affected by AMF. Interestingly, we revealed that AMF positively affected sulfur homeostasis under drought conditions, mainly in the Svevo cultivar. The results provide a valuable indication that the identification of drought tolerant plants cannot ignore their nutrient use efficiency or the impact of other biotic soil components (i.e., AMF). [ABSTRACT FROM AUTHOR]

While the individual influences of melatonin (MT) and polyamines (PAs) have been widely studied under various abiotic stresses, little is known about their interaction under salinity stress. In the present study, salt stress applied by 50 mM of sodium chloride (NaCl) on snap bean seedlings has been supplemented with 20 μM of MT and/or 100 μM of putrescine (Put) (individually and in combination). The results indicated that under salinity stress, the combination of MT + Put achieved the highest significant increase in shoot fresh and dry weight, chlorophyll (Chl a), Chl a + b, carotenoids, total soluble sugars, proline, K, Ca, and cell membrane stability index (CMSI), as well as catalase (CAT) and peroxidase (POX) activities. This improvement was associated with an obvious decrease in Na, Na/K ratio, and oxidative damage as indicated by reducing leaf contents of methylglyoxal (MG), hydrogen peroxide (H2O2), and the rate of lipid peroxidation (malondialdehyde; MDA). Moreover, the combination of MT + Put demonstrated a significant decrease in the activities of diamine oxidase (DAO) and polyamine oxidase (PAO) leading to the reduction of the rate of polyamine oxidation. Meanwhile, MT applied individually gave the highest significant increase in leaf relative water content (RWC), Chl b, superoxide dismutase (SOD), and ascorbate peroxidase (APX). Conclusively, the combination treatment of MT + Put could decrease the degradation of polyamines and enhance tolerance to salinity stress in snap bean seedlings.

Plants engage in symbiotic relationships with soil microorganisms to overcome nutrient limitations in their environment. Among the best studied endosymbiotic interactions in plants are those with arbuscular mycorrhizal (AM) fungi and N-fixing bacteria called rhizobia. The mechanisms regulating plant nutrient homeostasis and acquisition involve small mobile molecules such as peptides and micro RNAs (miRNAs). A large number of CLE (CLAVATA3/EMBRYO SURROUNDING REGION-RELATED) and CEP (C-TERMINALLY ENCODED PEPTIDE) peptide hormones as well as certain miRNAs have been reported to differentially respond to the availability of essential nutrients such as nitrogen (N) and phosphorus (P). Interestingly, a partially overlapping pool of these molecules is involved in plant responses to root colonization by rhizobia and AM fungi, as well as mineral nutrition. The crosstalk between root endosymbiosis and nutrient availability has been subject of intense investigations, and new insights in locally or systemically mobile molecules in nutrient- as well as symbiosis-related signaling continue to arise. Focusing on the key roles of peptides and miRNAs, we review the mechanisms that shape plant responses to nutrient limitation and regulate the establishment of symbiotic associations with beneficial soil microorganisms.

Iron (Fe) and phosphorus (P) are the essential mineral nutrients for plant growth and development. However, the molecular interaction of the Fe and P pathways in crops remained largely obscure. In this study, we provide a comprehensive physiological and molecular analysis of hexaploid wheat response to single (Fe, P) and its combinatorial deficiencies. Our data showed that inhibition of the primary root growth occurs in response to Fe deficiency; however, growth was rescued when combinatorial deficiencies occurred. Analysis of RNAseq revealed that distinct molecular rearrangements during combined deficiencies with predominance for genes related to metabolic pathways and secondary metabolite biosynthesis primarily include genes for UDP-glycosyltransferase, cytochrome-P450s, and glutathione metabolism. Interestingly, the Fe-responsive cis-regulatory elements in the roots in Fe stress conditions were enriched compared to the combined stress. Our metabolome data also revealed the accumulation of distinct metabolites such as amino-isobutyric acid, arabinonic acid, and aconitic acid in the combined stress environment. Overall, these results are essential in developing new strategies to improve the resilience of crops in limited nutrients. • This study attempts to understand the molecular changes occurring during the interaction of Phosphorus (P) and Iron (Fe) in hexaploid wheat roots. • P and Fe show cross-talk as Fe deficiency-induced phenotype that was restored by the withdrawal of P. • The –Fe–P deficiencies show predominance for UDP-glycosyltransferases, cytochrome-450 and glutathione-S-transferases transcripts. • The metabolomic changes identified the importance of amino-isobutyric acid, arabinonic acid and aconitic acid during dual deficiency. • This work provides a comprehensive insight to understand the molecular re-arrangements occurring in wheat roots during Fe and P interaction. [ABSTRACT FROM AUTHOR]

In nature, land plants as sessile organisms are faced with multiple nutrient stresses that often occur simultaneously in soil. Nitrogen (N), phosphorus (P), sulfur (S), zinc (Zn), and iron (Fe) are five of the essential nutrients that affect plant growth and health. Although these minerals are relatively inaccessible to plants due to their low solubility and relative immobilization, plants have adopted coping mechanisms for survival under multiple nutrient stress conditions. The double interactions between N, Pi, S, Zn, and Fe have long been recognized in plants at the physiological level. However, the molecular mechanisms and signaling pathways underlying these cross-talks in plants remain poorly understood. This review preliminarily examined recent progress and current knowledge of the biochemical and physiological interactions between macro- and micro-mineral nutrients in plants and aimed to focus on the cross-talks between N, Pi, S, Zn, and Fe uptake and homeostasis in plants. More importantly, we further reviewed current studies on the molecular mechanisms underlying the cross-talks between N, Pi, S, Zn, and Fe homeostasis to better understand how these nutrient interactions affect the mineral uptake and signaling in plants. This review serves as a basis for further studies on multiple nutrient stress signaling in plants. Overall, the development of an integrative study of multiple nutrient signaling cross-talks in plants will be of important biological significance and crucial to sustainable agriculture. [ABSTRACT FROM AUTHOR]

Zn deficiency is the most common micronutrient deficit in rice but Zn is also a widespread industrial pollutant. Zn deficiency responses in rice are well documented, but comparative responses to Zn deficiency and excess have not been reported. Therefore, we compared the physiological, transcriptional and biochemical properties of rice subjected to Zn starvation or excess at early and later treatment stages. Both forms of Zn stress inhibited root and shoot growth. Gene ontology analysis of differentially expressed genes highlighted the overrepresentation of Zn transport and antioxidative defense for both Zn stresses, whereas diterpene biosynthesis was solely induced by excess Zn. Divalent cations (Fe, Cu, Ca, Mn and Mg) accumulated in Zn‐deficient shoots but Mg and Mn were depleted in the Zn excess shoots, mirroring the gene expression of non‐specific Zn transporters and chelators. Ascorbate peroxidase activity was induced after 14 days of Zn starvation, scavenging H2O2 more effectively to prevent leaf chlorosis via the Fe‐dependent Fenton reaction. Conversely, excess Zn triggered the expression of genes encoding Mg/Mn‐binding proteins (OsCPS2/4 and OsKSL4/7) required for antimicrobial diterpenoid biosynthesis. Our study reveals the potential role of divalent cations in the shoot, driving the unique responses of rice to each form of Zn stress. Comprehensive responses to Zn deficiency and excess were compared in rice. We showed the differential expression of non‐specific Zn transporter and chelator genes alters the concentrations of divalent cations in shoots that potentially drives the unique responses of rice to each form of Zn stress. [ABSTRACT FROM AUTHOR]

Mechanisms of iron-deficiency tolerance and signalling were investigated in a dill (Anethum graveolens) cultivar using metabolic and physiological approaches. When grown under direct iron (Fe) deprivation, severe chlorosis symptoms and necrosis appeared. Such manifestations led to a significant reduction of photosynthetic gas exchange parameters, pigment contents along with changeability in mineral homeostasis. Roots were the main organ affected regarding variations in the phenolic pools and their respective functionalities. Methanolic extracts from Fe deficient roots showed a remarkable increase in total phenolic content (+26%) and total flavonoid content (+21%) when compared to equivalent extracts from control plants. Likewise, they exhibited a higher total antioxidant capacity and scavenging abilities toward ABTS•+ and RO2• radicals, as well as a noteworthy ferric reducing antioxidant power with efficient anti-LOX inhibitory activity. Overall, the tolerance of dill was associated to its suitable manipulation to produce antioxidants with an orderly regulation of nutrient homeostasis, notably in deficient Fe roots. [ABSTRACT FROM AUTHOR]

Abstract During past decades, many lakes underwent drastic human‐caused changes in trophic state with strong implications for population dynamics and food web processes. We investigated the influence of trophic state on nutrient allocation into Daphnia resting eggs. The production of resting eggs is an important survival strategy, allowing Daphnia to cope with unfavorable environmental conditions. Allocation of essential nutrients into resting eggs may crucially influence embryonic development and offspring survival and thus is of great ecological and evolutionary interest. The capacity of Daphnia to adjust the allocation of nutrients into resting eggs may depend on the dietary nutrient supply, which may vary with trophic state‐related changes in the phytoplankton community composition. Resting eggs were isolated from sediment cores taken from Lake Constance, a large prealpine lake with a distinct eutrophication and reoligotrophication history, and analyzed for elemental (carbon, nitrogen, and phosphorus) and biochemical (sterols and fatty acids) nutrients. Carbon allocation into Daphnia resting eggs continuously decreased over time, irrespective of changes in trophic state. The allocation of nitrogen into Daphnia resting eggs followed the changes in trophic state, that is, nitrogen concentrations in resting eggs increased with eutrophication and decreased again with reoligotrophication. The allocation of phosphorus, sterols and long‐chain polyunsaturated fatty acids, such as eicosapentaenoic acid, into Daphnia resting eggs did not change significantly over time. Changes in trophic state strikingly influenced all trophic levels in Lake Constance. However, nutrient allocation into Daphnia resting eggs was mostly resilient to changes in lake trophic state.

Nitrogen (N), phosphorus (P), sulfur (S), zinc (Zn), and iron (Fe) are some of the vital nutrients required for optimum growth, development, and productivity of plants. The deficiency of any of these nutrients may lead to defects in plant growth and decreased productivity. Plant responses to the deficiency of N, P, S, Fe, or Zn have been studied mainly as a separate event, and only a few reports discuss the molecular basis of biological interaction among the nutrients. Macro-nutrients like N, P, and/or S not only show the interacting pathways for each other but also affect micro-nutrient pathways. Limited reports are available on the investigation of two-by-two or multi-level nutrient interactions in plants. Such studies on the nutrient interaction pathways suggest that an MYB-like transcription factor, phosphate starvation response 1 (PHR1), acts as a master regulator of N, P, S, Fe, and Zn homeostasis. Similarly, light-responsive transcription factors were identified to be involved in modulating nutrient responses in Arabidopsis. This review focuses on the recent advances in our understanding of how plants coordinate the acquisition, transport, signaling, and interacting pathways for N, P, S, Fe, and Zn nutrition at the molecular level. Identification of the important candidate genes for interactions between N, P, S, Fe, and/or Zn metabolic pathways might be useful for the breeders to improve nutrient use efficiency and yield/quality of crop plants. Integrated studies on pathways interactions/cross-talks between macro‐ and micro-nutrients in the agronomically important crop plants would be essential for sustainable agriculture around the globe, particularly under the changing climatic conditions.