Plant Metabolism Responses Research Articles

Young Tomato Plants Respond Differently under Single or Combined Mild Nitrogen and Water Deficit: An Insight into Morphophysiological Responses and Primary Metabolism.

This study aimed to understand the morphophysiological responses and primary metabolism of tomato seedlings subjected to mild levels of nitrogen and/or water deficit (50% N and/or 50% W). After 16 days of exposure, plants grown under the combined deficit showed similar behavior to the one found upon exposure to single N deficit. Both N deficit treatments resulted in a significantly lower dry weight, leaf area, chlorophyll content, and N accumulation but in a higher N use efficiency when compared to control (CTR) plants. Moreover, concerning plant metabolism, at the shoot level, these two treatments also responded in a similar way, inducing higher C/N ratio, nitrate reductase (NR) and glutamine synthetase (GS) activity, expression of RuBisCO encoding genes as well as a downregulation of GS2.1 and GS2.2 transcripts. Interestingly, plant metabolic responses at the root level did not follow the same pattern, with plants under combined deficit behaving similarly to W deficit plants, resulting in enhanced nitrate and proline concentrations, NR activity, and an upregulation of GS1 and NR genes than in CTR plants. Overall, our data suggest that the N remobilization and osmoregulation strategies play a relevant role in plant acclimation to these abiotic stresses and highlight the complexity of plant responses under a combined N+W deficit.

Beneficial Role of Multi-Walled Carbon Nanotubes on Physiological and Phytochemical Responses of Mentha piperita L under Salinity Stress

MWCNTs (Multiwalled Carbon Nanotubes) are nanomaterials that can enter the soil through various sources. Our understanding of the effects of MWCNT on plant growth is not yet complete and needs to be further studied. In this study, the possible effects of MWCNTs (0, 50 μg/ml, 200 μg/ml) on the growth, physiological, and phytochemical performance of Mentha piperita plants under 50, 100, and 200 mM NaCl stress in greenhouse conditions were investigated. Changes in the essential oil of M. piperita were analyzed by GC. The most physiological and photosynthesis characteristics of M. piperita seedlings were negatively affected when plants were grown at different concentrations of NaCl. With increasing the salt concentration to 200 mM, a significant decrease was observed in the fresh and dry weight of the plant and the number of plant branches. The presence of both doses of MWCNTs significantly enhanced relative water content (RWC), chlorophyll content, growth indices, and essential oil percentage. Also, the plants treated with both MWCNTs and NaCl showed higher antioxidant enzyme activities such as superoxide catalase and peroxidase content under salinity stress. Among the different concentrations of carbon nanotubes, 200 μg/ml has a potential effect on physiological and biochemical parameters in plants under salinity stress. It is proposed that MWCNTs can significantly improve growth and salt tolerance in M. piperita plants by promoting water uptake, antioxidant enzyme activity, and photosynthesis performance. It can be concluded that MWCNTs improved the stress condition for the plant and reduced the plant's metabolic response to stress.

Smart Farming Enhances Bioactive Compounds Content of Panax ginseng on Moderating Scopolamine-Induced Memory Deficits and Neuroinflammation.

Korean ginseng (Panax ginseng) is a traditional herbal supplement known to have a variety of pharmacological activities. A smart farm system could provide potential standardization of ginseng seedlings after investigating plant metabolic responses to various parameters in order to design optimal conditions. This research was performed to investigate the effect of smart-farmed ginseng on memory improvement in a scopolamine-induced memory deficit mouse model and an LPS-induced microglial cell model. A smart farming system was applied to culture ginseng. The administration of its extract (S2 extract) under specific culture conditions significantly attenuated cognitive and spatial memory deficits by regulating AKT/ERK/CREB signaling, as well as the cortical inflammation associated with suppression of COX-2 and NLRP3 induced by scopolamine. In addition, S2 extract improved the activation of iNOS and COX-2, and the secretion of NO in LPS-induced BV-2 microglia. Based on the HPLC fingerprint and in vitro data, ginsenosides Rb2 and Rd were found to be the main contributors to the anti-inflammatory effects of the S2 extract. Our findings suggest that integrating a smart farm system may enhance the metabolic productivity of ginseng and provides evidence of its potential impact on natural bioactive compounds of medicinal plants with beneficial qualities, such as ginsenosides Rb2 and Rd.

Applications of Metabolomics for the Elucidation of Abiotic Stress Tolerance in Plants: A Special Focus on Osmotic Stress and Heavy Metal Toxicity.

Plants undergo metabolic perturbations under various abiotic stress conditions; due to their sessile nature, the metabolic network of plants requires continuous reconfigurations in response to environmental stimuli to maintain homeostasis and combat stress. The comprehensive analysis of these metabolic features will thus give an overview of plant metabolic responses and strategies applied to mitigate the deleterious effects of stress conditions at a biochemical level. In recent years, the adoption of metabolomics studies has gained significant attention due to the growing technological advances in analytical biochemistry (plant metabolomics). The complexity of the plant biochemical landscape requires sophisticated, advanced analytical methods. As such, technological advancements in the field of metabolomics have been realized, aided much by the development and refinement of separatory techniques, including liquid and gas chromatography (LC and GC), often hyphenated to state-of-the-art detection instruments such as mass spectrometry (MS) or nuclear resonance magnetic (NMR) spectroscopy. Significant advances and developments in these techniques are briefly highlighted in this review. The enormous progress made thus far also comes with the dawn of the Internet of Things (IoT) and technology housed in machine learning (ML)-based computational tools for data acquisition, mining, and analysis in the 4IR era allowing for broader metabolic coverage and biological interpretation of the cellular status of plants under varying environmental conditions. Thus, scientists can paint a holistic and comprehensive roadmap and predictive models for metabolite-guided crop improvement. The current review outlines the application of metabolomics and related technological advances in elucidating plant responses to abiotic stress, mainly focusing on heavy metal toxicity and subsequent osmotic stress tolerance.

Ammonium Uptake, Mediated by Ammonium Transporters, Mitigates Manganese Toxicity in Duckweed, Spirodela polyrhiza.

Nitrogen is an essential nutrient that affects all aspects of the growth, development and metabolic responses of plants. Here we investigated the influence of the two major sources of inorganic nitrogen, nitrate and ammonium, on the toxicity caused by excess of Mn in great duckweed, Spirodela polyrhiza. The revealed alleviating effect of ammonium on Mn-mediated toxicity, was complemented by detailed molecular, biochemical and evolutionary characterization of the species ammonium transporters (AMTs). Four genes encoding AMTs in S. polyrhiza, were classified as SpAMT1;1, SpAMT1;2, SpAMT1;3 and SpAMT2. Functional testing of the expressed proteins in yeast and Xenopus oocytes clearly demonstrated activity of SpAMT1;1 and SpAMT1;3 in transporting ammonium. Transcripts of all SpAMT genes were detected in duckweed fronds grown in cultivation medium, containing a physiological or 50-fold elevated concentration of Mn at the background of nitrogen or a mixture of nitrate and ammonium. Each gene demonstrated an individual expression pattern, revealed by RT-qPCR. Revealing the mitigating effect of ammonium uptake on manganese toxicity in aquatic duckweed S. polyrhiza, the study presents a comprehensive analysis of the transporters involved in the uptake of ammonium, shedding a new light on the interactions between the mechanisms of heavy metal toxicity and the regulation of the plant nitrogen metabolism.

Functional and biotechnological cues of potassium homeostasis for stress tolerance and plant development

ABSTRACT Potassium (K+) is indispensable for the regulation of a plethora of functions like plant metabolism, growth, development, and abiotic stress responses. K+ is associated with protein synthesis and entangled in the activation of scores of enzymes, stomatal regulation, and photosynthesis. It has multiple transporters and channels that assist in the uptake, efflux, transport within the cell as well as from soil to different tissues, and the grain filling sites. While it is implicated in ion homeostasis during salt stress, it acts as a modulator of stomatal movements during water deficit conditions. K+ is reported to abate the effects of chilling and photooxidative stresses. K+ has been found to ameliorate effectively the co-occurrence of drought and high-temperature stresses. Nutrient deficiency of K+ makes leaves necrotic, leads to diminished photosynthesis, and decreased assimilate utilization highlighting the role it plays in photosynthesis. Notably, K+ is associated with the detoxification of reactive oxygen species (ROS) when plants are exposed to diverse abiotic stress conditions. It is irrefutable now that K+ reduces the activity of NADPH oxidases and at the same time maintains electron transport activity, which helps in mitigating the oxidative stress. K+ as a macronutrient in plant growth, the role of K+ during abiotic stress and the protein phosphatases involved in K+ transport have been reviewed. This review presents a holistic view of the biological functions of K+, its uptake, translocation, signaling, and the critical roles it plays under abiotic stress conditions, plant growth, and development that are being unraveled in recent times.

Identification and Characterization of AP2/ERF Transcription Factors in Yellow Horn

The AP2/ERF gene family involves numerous plant processes, including growth, development, metabolism, and various plant stress responses. However, several studies have been conducted on the AP2/ERF gene family in yellow horn, a new type of oil woody crop and an essential oil crop in China. According to sequence alignment and phylogenetic analyses, one hundred and forty-five AP2/ERF genes were detected from the yellow horn genome. They were divided into four relatively conserved subfamilies, including 21 AP2 genes, 119 ERBP genes, 4 RAV genes, and 1 Soloist gene. Gene analysis of XsAP2/ERF TFs showed 87 XsAP2/ERF TFs lacked introns. There were 75 pairs of collinearity relationships between X. sorbifolium and Arabidopsis, indicating a close similarity. In addition, the expression patterns of XsAP2/ERF TFs under cold treatments confirmed that the XsAP2/ERF TFs play essential roles in abiotic stress response. The expression of eight XsAP2/ERF transcription factors was verified in different tissues and under various stress treatments using RT-qPCR. This study establishes a starting point for further research to explore the potential mechanisms of identifying candidate AP2/ERF TFs that could respond to the abiotic stress of yellow horn.

Environmental Signals Act as a Driving Force for Metabolic and Defense Responses in the Antarctic Plant Colobanthus quitensis.

During evolution, plants have faced countless stresses of both biotic and abiotic nature developing very effective mechanisms able to perceive and counteract adverse signals. The biggest challenge is the ability to fine-tune the trade-off between plant growth and stress resistance. The Antarctic plant Colobanthus quitensis has managed to survive the adverse environmental conditions of the white continent and can be considered a wonderful example of adaptation to prohibitive conditions for millions of other plant species. Due to the progressive environmental change that the Antarctic Peninsula has undergone over time, a more comprehensive overview of the metabolic features of C. quitensis becomes particularly interesting to assess its ability to respond to environmental stresses. To this end, a differential proteomic approach was used to study the response of C. quitensis to different environmental cues. Many differentially expressed proteins were identified highlighting the rewiring of metabolic pathways as well as defense responses. Finally, a different modulation of oxidative stress response between different environmental sites was observed. The data collected in this paper add knowledge on the impact of environmental stimuli on plant metabolism and stress response by providing useful information on the trade-off between plant growth and defense mechanisms.

Targeted and non-targeted analysis for the investigation of pesticides influence on wheat cultivated under field conditions

A comprehensive approach was applied to evaluate the effects of pesticides on the metabolism of wheat (Triticum aestivum L). The application of commercially available pesticide formulations under field cultivation conditions provided a source of metabolic data unlimited by model conditions, representing a novel approach to study the effects of pesticides on edible plants. Gas and liquid chromatography coupled to tandem mass spectrometry were employed for targeted and non-targeted analysis of wheat roots and shoots sampled six times during the six-week experiment. The applied pesticides: prothioconazole, tebuconazole, fluoxastrobin, diflufenican, florasulam, and penoxulam were found at concentrations ranging 0.0070–25.20 mg/kg and 0.0020–2.2 mg/kg in the wheat roots and shoots, respectively. The following pesticide metabolites were identified in shoots: prothioconazole-desthio (prothioconazole metabolite), 5-(4-chlorophenyl)-2,2-dimethyl-3-(1,2,4-triazol-1-ylmethyl)pentane-1,3-diol (tebuconazole metabolite), and N-(5,8-dimethoxy[1,2,4]triazolo[1,5-c]pyrimidin-2-yl)-2,4-dihydroxy-6-(trifluoromethyl)benzene sulphonamide (penoxulam metabolite). The metabolic fingerprints and profiles changed during the experiment, reflecting the cumulative response of wheat to both its growth environment and pesticides, as well as their metabolites. Approximately 15 days after the herbicide treatment no further changes in the plant metabolic profiles were observed, despite the presence of pesticide and their metabolites in both roots and shoots. This is the first study to combine the determination of pesticides and their metabolites plant tissues with the evaluation of plant metabolic responses under field conditions. This exhaustive approach contributes to broadening the knowledge of pesticide effects on edible plants, relevant to food safety.

Identification and characteristics of SnRK genes and cold stress-induced expression profiles in Liriodendron chinense

BackgroundThe sucrose non-fermenting 1 (SNF1)-related protein kinases (SnRKs) play a vivid role in regulating plant metabolism and stress response, providing a pathway for regulation between metabolism and stress signals. Conducting identification and stress response studies on SnRKs in plants contributes to the development of strategies for tree species that are more tolerant to stress conditions.ResultsIn the present study, a total of 30 LcSnRKs were identified in Liriodendron chinense (L. chinense) genome, which was distributed across 15 chromosomes and 4 scaffolds. It could be divided into three subfamilies: SnRK1, SnRK2, and SnRK3 based on phylogenetic analysis and domain types. The LcSnRK of the three subfamilies shared the same Ser/Thr kinase structure in gene structure and motif composition, while the functional domains, except for the kinase domain, showed significant differences. A total of 13 collinear gene pairs were detected in L. chinense and Arabidopsis thaliana (A. thaliana), and 18 pairs were detected in L. chinense and rice, suggesting that the LcSnRK family genes may be evolutionarily more closely related to rice. Cis-regulation element analysis showed that LcSnRKs were LTR and TC-rich, which could respond to different environmental stresses. Furthermore, the expression patterns of LcSnRKs are different at different times under low-temperature stress. LcSnRK1s expression tended to be down-regulated under low-temperature stress. The expression of LcSnRK2s tended to be up-regulated under low-temperature stress. The expression trend of LcSnRK3s under low-temperature stress was mainly up-or down-regulated.ConclusionThe results of this study will provide valuable information for the functional identification of the LcSnRK gene in the future.

Proteome-wide identification of S-sulfenylated cysteines reveals metabolic response to freezing stress after cold acclimation in Brassica napus.

Redox regulation plays a wide role in plant growth, development, and adaptation to stresses. Sulfenylation is one of the reversible oxidative post-transcriptional modifications. Here we performed an iodoTMT-based proteomic analysis to identify the redox sensitive proteins in vivo under freezing stress after cold acclimation in Brassica napus. Totally, we obtained 1,372 sulfenylated sites in 714 proteins. The overall sulfenylation level displayed an increased trend under freezing stress after cold acclimation. We identified 171 differentially sulfenylated proteins (DSPs) under freezing stress, which were predicted to be mainly localized in chloroplast and cytoplasm. The up-regulated DSPs were mainly enriched in photosynthesis and glycolytic processes and function of catalytic activity. Enzymes involved in various pathways such as glycolysis and Calvin-Benson-Bassham (CBB) cycle were generally sulfenylated and the metabolite levels in these pathways was significantly reduced under freezing stress after cold acclimation. Furthermore, enzyme activity assay confirmed that the activity of cytosolic pyruvate kinase and malate dehydrogenase 2 was significantly reduced under H2O2 treatment. Our study provides a landscape of redox sensitive proteins in B. napus in response to freezing stress after cold acclimation, which proposes a basis for understanding the redox regulation in plant metabolic response to freezing stress after cold acclimation.

Phytoecdysteroids: Distribution, Structural Diversity, Biosynthesis, Activity, and Crosstalk with Phytohormones.

Phytoecdysteroids (PEs) are naturally occurring polyhydroxylated compounds with a structure similar to that of insect molting hormone and the plant hormone brassinosteroids. PEs have a four-ringed skeleton composed of 27, 28, 29, or 30 carbon atoms (derived from plant sterols). The carbon skeleton of ecdysteroid is known as cyclopentanoperhydrophenanthrene and has a β-sidechain on C-17. Plants produce PEs via the mevalonate pathway with the help of the precursor acetyl-CoA. PEs are found in algae, fungi, ferns, gymnosperms, and angiosperms; more than 500 different PEs are found in over 100 terrestrial plants. 20-hydroxyecdysone is the most common PE. PEs exhibit versatile biological roles in plants, invertebrates, and mammals. These compounds contribute to mitigating biotic and abiotic stresses. In plants, PEs play a potent role in enhancing tolerance against insects and nematodes via their allelochemical activity, which increases plant biological and metabolic responses. PEs promote enzymatic and non-enzymatic antioxidant defense systems, which decrease reactive oxygen species in the form of superoxide radicals and hydroxyl radicals and reduce malondialdehyde content. PEs also induce protein biosynthesis and modulate carbohydrate and lipid synthesis. In humans, PEs display biological, pharmacological, and medicinal properties, such as anti-diabetic, antioxidant, anti-microbial, hepatoprotective, hypoglycemic, anti-cancer, anti-inflammatory, antidepressant, and tissue differentiation activity.

Single, but not dual, attack by a biotrophic pathogen and a sap-sucking insect affects the oak leaf metabolome.

Plants interact with a multitude of microorganisms and insects, both below- and above ground, which might influence plant metabolism. Despite this, we lack knowledge of the impact of natural soil communities and multiple aboveground attackers on the metabolic responses of plants, and whether plant metabolic responses to single attack can predict responses to dual attack. We used untargeted metabolic fingerprinting (gas chromatography-mass spectrometry, GC-MS) on leaves of the pedunculate oak, Quercus robur, to assess the metabolic response to different soil microbiomes and aboveground single and dual attack by oak powdery mildew (Erysiphe alphitoides) and the common oak aphid (Tuberculatus annulatus). Distinct soil microbiomes were not associated with differences in the metabolic profile of oak seedling leaves. Single attacks by aphids or mildew had pronounced but different effects on the oak leaf metabolome, but we detected no difference between the metabolomes of healthy seedlings and seedlings attacked by both aphids and powdery mildew. Our findings show that aboveground attackers can have species-specific and non-additive effects on the leaf metabolome of oak. The lack of a metabolic signature detected by GC-MS upon dual attack might suggest the existence of a potential negative feedback, and highlights the importance of considering the impacts of multiple attackers to gain mechanistic insights into the ecology and evolution of species interactions and the structure of plant-associated communities, as well as for the development of sustainable strategies to control agricultural pests and diseases and plant breeding.

Identifying and expression analysis of WD40 transcription factors in walnut.

Walnut (Juglans regia L.) is an important woody oil plant and will be affected by abiotic and biological stress during its growth and development. The WD-repeat (WD40) protein is widely involved in plant growth, development, metabolism, and abiotic stress response. To explore the stress response mechanism of walnut, based on the complete sequencing results of the walnut genome, this study identified and analyzed the physiological, biochemical, genetic structure, and conservative protein motifs of 42 JrWD40 genes, whose expression to abnormal temperature were tested to predict the potential biological function. The results showed that the open reading frame (ORF) of theseWD40 genes were 807-2,460 bp, encoding peptides were 29,610.55-90,387.98 Da covering 268-819 amino acids, as well as 12-112 phosphorylation sites. JrWD40 proteins were highly conserved with four to five WD40 domains and shared certain similarity to WD40 proteins from Arabidopsis thaliana (L.) Heynh. JrWD40 genes can be induced to varying degrees by low and high temperature treatments. JrWD40-32, JrWD40-27, JrWD40-35, and JrWD40-21 are affected by high temperature more seriously and their expression levels are higher; while JrWD40-37, JrWD40-26, JrWD40-20, JrWD40-24, and other genes are inhibited under low temperature stress. JrWD40-40, JrWD40-28, and JrWD40-18 were first suppressed with low expression, while as the treatment time prolonging, the expression level was increased under cold condition. JrWD40-14, JrWD40-18, JrWD40-34, and JrWD40-3 displayed strong transcriptions response to both heat and cold stress. These results indicated that JrWD40 genes can participate in walnut adaptation to adversity and can be used as important candidates for walnut resistance molecular breeding.

Nitrogen Source Matters: High NH4/NO3 Ratio Reduces Cannabinoids, Terpenoids, and Yield in Medical Cannabis.

The N form supplied to the plant, ammonium (NH4+) or nitrate (NO3–), is a major factor determining the impact of N nutrition on plant function and metabolic responses. We have hypothesized that the ratio of NH4/NO3 supplied to cannabis plants affects the physiological function and the biosynthesis of cannabinoids and terpenoids, which are major factors in the cannabis industry. To evaluate the hypothesis we examined the impact of five supply ratios of NH4/NO3 (0, 10, 30, 50, and 100% N-NH4+, under a uniform level of 200 mg L–1 N) on plant response. The plants were grown in pots, under controlled environment conditions. The results revealed high sensitivity of cannabinoid and terpenoid concentrations and plant function to NH4/NO3 ratio, thus supporting the hypothesis. The increase in NH4 supply generally caused an adverse response: Secondary metabolite production, inflorescence yield, plant height, inflorescence length, transpiration and photosynthesis rates, stomatal conductance, and chlorophyll content, were highest under NO3 nutrition when no NH4 was supplied. Ratios of 10–30% NH4 did not substantially impair secondary metabolism and plant function, but produced smaller inflorescences and lower inflorescence yield compared with only NO3 nutrition. Under a level of 50% NH4, the plants demonstrated toxicity symptoms, which appeared only at late stages of plant maturation, and 100% NH4 induced substantial plant damage, resulting in plant death. This study demonstrates a dramatic impact of N form on cannabis plant function and production, with a 46% decrease in inflorescence yield with the increase in NH4 supply from 0 to 50%. Yet, moderate levels of 10–30% NH4 are suitable for medical cannabis cultivation, as they do not damage plant function and show only little adverse influence on yield and cannabinoid production. Higher NH4/NO3 ratios, containing above 30% NH4, are not recommended since they increase the potential for a severe and fatal NH4 toxicity damage.

Abscisic acid facilitates phosphate acquisition through the transcription factor ABA INSENSITIVE5 in Arabidopsis

Low phosphate (LP) in soil is a common nutrient stress that severely restricts agricultural production, but the role, if any, of the major stress phytohormone abscisic acid (ABA) in plant phosphate (Pi) starvation responses remains elusive. Here, we report that LP-induced ABA accumulation promotes Pi uptake in an ABA INSENSITIVE5 (ABI5)-dependent manner in Arabidopsis thaliana. LP significantly activated plant ABA biosynthesis, metabolism, and stress responses, suggesting a role of ABA in the plant response to Pi availability. LP-induced ABA accumulation and expression of two major high-affinity phosphate transporter genes PHOSPHATE TRANSPORTER1;1/1;4 (PHT1;1/1;4) were severely impaired in a mutant lacking BETA-GLUCOSIDASE1 (BG1), which converts conjugated ABA to active ABA, and the mutant had shorter roots and less Pi content than wild-type plants under LP conditions. Moreover, a mutant of ABI5, which encodes a central transcription factor in ABA signaling, also exhibited suppressed root elongation and had reduced Pi content under LP conditions. ABI5 facilitated Pi acquisition by activating the expression of PHT1;1 by directly binding to its promoter, while overexpression of PHT1;1 completely rescued its Pi content under LP conditions. Together, our findings illustrate a molecular mechanism by which ABA positively modulates phosphate acquisition through ABI5 in the Arabidopsis response to phosphate deficiency.

Molecular mechanisms underlying nitrate responses in plants

Nitrate is an important source of inorganic nitrogen. Nitrate modulates many plant metabolic, physiological, and developmental processes. This minireview highlights recent findings on the intricate molecular wiring that allows plants to adapt to environmental nitrate conditions. We focus on the role of regulatory pathways and their components - transporters, receptors, second messengers, kinases, and transcription factors - in mediating plant metabolic and developmental responses to nitrate. Work is still needed to identify missing components of the nitrate signaling pathway and their interplay with known and well-characterized master regulators and to validate their molecular interactions to explain the complexity of phenotypical responses to nitrate. Understanding how plants perceive nitrate and transduce it into responses at the molecular level is crucial to optimize nitrogen-use efficiency, improve crop yield and mitigate the adverse environmental impacts of fertilizer overuse in a changing world.

Root metabolome of plant-arbuscular mycorrhizal symbiosis mirrors the mutualistic or parasitic mycorrhizal phenotype.

The symbiosis of arbuscular mycorrhizal fungi (AMF) with plants, the most ancient and widespread association, exhibits phenotypes that range from mutualism to parasitism. However, we still lack an understanding of the cellular-level mechanisms that differentiate and regulate these phenotypes. We assessed the modulation in growth parameters and root metabolome of two sorghum accessions inoculated with two AMF species (Rhizophagus irregularis, Gigaspora gigantea), alone and in a mixture under phosphorus (P) limiting conditions. Rhizophagus irregularis exhibited a mutualistic phenotype with increased P uptake and plant growth. This positive outcome was associated with a facilitatory metabolic response including higher abundance of organic acids and specialized metabolites critical to maintaining a functional symbiosis. However, G. gigantea exhibited a parasitic phenotype that led to plant growth depression and resulted in inhibitory plant metabolic responses including the higher abundance of p-hydroxyphenylacetaldoxime with antifungal properties. These findings suggest that the differential outcome of plant-AMF symbiosis could be regulated by or reflected in changes in the root metabolome that arises from the interaction of the plant species with the specific AMF species. A mutualistic symbiotic association prevailed when the host plants were exposed to a mixture of AMF. Our results provide a metabolome-level landscape of plant-AMF symbiosis and highlight the importance of the identity of both AMF and crop genotypes in facilitating a mutualistic AMF symbiosis.

γ-Aminobutyric acid plays a key role in plant acclimation to a combination of high light and heat stress.

Plants are frequently subjected to different combinations of abiotic stresses, such as high light (HL) intensity, and elevated temperatures. These environmental conditions pose a threat to agriculture production, affecting photosynthesis, and decreasing yield. Metabolic responses of plants, such as alterations in carbohydrates and amino acid fluxes, play a key role in the successful acclimation of plants to different abiotic stresses, directing resources toward stress responses, and suppressing growth. Here we show that the primary metabolic response of Arabidopsis (Arabidopsis thaliana) plants to HL or heat stress (HS) is different from that of plants subjected to a combination of HL and HS (HL+HS). We further demonstrate that the combined stress results in a unique metabolic response that includes increased accumulation of sugars and amino acids coupled with decreased levels of metabolites participating in the tricarboxylic acid cycle. Among the amino acids exclusively accumulated during HL+HS, we identified the nonproteinogenic amino acid γ-aminobutyric acid (GABA). Analysis of different mutants deficient in GABA biosynthesis (GLUTAMATE DESCARBOXYLASE 3 [gad3]) as well as mutants impaired in autophagy (autophagy-related proteins 5 and 9 [atg5 and atg9]), revealed that GABA plays a key role in the acclimation of plants to HL+HS, potentially by promoting autophagy. Taken together, our findings identify a role for GABA in regulating plant responses to combined stress.

Mass Spectrometry Imaging Disclosed Spatial Distribution of Defense-Related Metabolites in Triticum spp.

Fusarium Head Blight is the most common fungal disease that strongly affects Triticum spp., reducing crop yield and leading to the accumulation of toxic metabolites. Several studies have investigated the plant metabolic response to counteract mycotoxins accumulation. However, information on the precise location where the defense mechanism is taking place is scarce. Therefore, this study aimed to investigate the specific tissue distribution of defense metabolites in two Triticum species and use this information to postulate on the metabolites’ functional role, unlocking the “location-to-function” paradigm. To address this challenge, transversal cross-sections were obtained from the middle of the grains. They were analyzed using an atmospheric-pressure (AP) SMALDI MSI source (AP-SMALDI5 AF, TransMIT GmbH, Giessen, Germany) coupled to a Q Exactive HF (Thermo Fisher Scientific GmbH, Bremen, Germany) orbital trapping mass spectrometer. Our result revealed the capability of (AP)-SMALDI MSI instrumentation to finely investigate the spatial distribution of wheat defense metabolites, such as hydroxycinnamic acid amides, oxylipins, linoleic and α-linoleic acids, galactolipids, and glycerolipids.