GABA signaling: a conserved and ubiquitous mechanism

Impact of germination on the techno-functional properties, nutritional composition, and health-promoting compounds of brown rice and its products: A review

Rice is a popular grain and forms part of the daily diet of people throughout the world. However, the consumption of rice and its products is sometimes limited by its high glycemic index due to its high starch content, low protein content and quality, and low bioavailability of minerals due to the presence of anti-nutritional factors. This has partly stimulated research interest in recent times toward the use of bioprocessing techniques such as germination as cheap and natural means to improve the nutritional quality, digestibility, and health properties of cereals, including rice, to partially achieve nutrition and food security in the developing regions of the world. This review highlights the impact of germination on the nutritional quality, health-promoting properties, and techno-functional characteristics of germinated brown rice grains and their products. The review demonstrated that germinated rice grains and their products have improved nutritional quality and digestibility, modified functional properties, and showed antioxidant, anti-inflammatory, anti-diabetic, anti-obesity, anti-cancer, and anti-cardiovascular activities. Germination appears to be a suitable bioprocessing method to improve the nutritional quality and bioactive constituents and modify the techno-functional properties of rice grains for diverse food applications and improved global nutrition and food safety.

CmCML11 interacts with CmCAMTA5 to enhance γ-aminobutyric acid (GABA) accumulation by regulating GABA shunt in fresh-cut cantaloupe

The effect of calcium chloride (CaCl2) treatment on γ-aminobutyric acid (GABA) accumulation in fresh-cut cantaloupe and the involved mechanisms were investigated. The result showed that 1% (w/v) CaCl2 treatment increased GABA content and activities of glutamate decarboxylase (GAD) and succinate semialdehyde dehydrogenase (SSADH), while decreased glutamate (Glu) content and GABA transaminase (GABA-T) activities in fresh-cut cantaloupe. CmCML11 and CmCAMTA5 expressions of CaCl2-treated fruit increased by 187.4% and 165.6% than control fruit in the initial 6 h. Besides, expressions of GABA shunt genes, including CmGAD1, CmGAD2, CmGABA-T and CmSSADH were also up-regulated by CaCl2 treatment during early storage. Moreover, acting as a transcriptional activator, CmCAMTA5 could bind to the CG-box in promoters of CmGAD1, CmGABA-T and CmSSADH and activate their transcription. Furthermore, the interaction between CmCML11 and CmCAMTA5 could enhance the transcriptional activation on GABA shunt genes which were regulated by CmCAMTA5. Collectively, our findings revealed that CaCl2 treatment promoted GABA accumulation in fresh-cut cantaloupe via the combined effect of CmCML11 and CmCAMTA5 in the regulation of expressions of CmGAD1, CmGABA-T, and CmSSADH in GABA shunt.

The GABA shunt contributes to ROS homeostasis in guard cells of Arabidopsis

γ-Aminobutyric acid (GABA) accumulates rapidly under stress via the GABA shunt pathway, which has been implicated in reducing the accumulation of stress-induced reactive oxygen species (ROS) in plants. γ-Aminobutyric acid has been demonstrated to act as a guard-cell signal in Arabidopsis thaliana, modulating stomatal opening. Knockout of the major GABA synthesis enzyme Glutamate Decarboxylase 2 (GAD2) increases the aperture of gad2 mutants, which results in greater stomatal conductance and reduces water-use efficiency compared with wild-type plants. Here, we found that the additional loss of GAD1, GAD4, and GAD5 in gad2 leaves increased GABA deficiency but abolished the more open stomatal pore phenotype of gad2, which we link to increased cytosolic calcium (Ca2+ ) and ROS accumulation in gad1/2/4/5 guard cells. Compared with wild-type and gad2 plants, glutamate was ineffective in closing gad1/2/4/5 stomatal pores, whereas lowering apoplastic calcium, applying ROS inhibitors or complementation with GAD2 reduced gad1/2/4/5 guard-cell ROS, restored the gad2-like greater stomatal apertures of gad1/2/4/5 beyond that of wild-type. We conclude that GADs are important contributors to ROS homeostasis in guard cells likely via a Ca2+ -mediated pathway. As such, this study reveals greater complexity in GABA's role as a guard-cell signal and the interactions it has with other established signals.

Biosynthesis of Gamma-Aminobutyric Acid (GABA) by Lactiplantibacillus plantarum in Fermented Food Production

In recent decades, given the important role of gamma-aminobutyric acid (GABA) in human health, scientists have paid great attention to the enrichment of this chemical compound in food using various methods, including microbial fermentation. Moreover, GABA or GABA-rich products have been successfully commercialized as food additives or functional dietary supplements. Several microorganisms can produce GABA, including bacteria, fungi, and yeasts. Among GABA-producing microorganisms, lactic acid bacteria (LAB) are commonly used in the production of many fermented foods. Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) is a LAB species that has a long history of natural occurrence and safe use in a wide variety of fermented foods and beverages. Within this species, some strains possess not only good pro-technological properties but also the ability to produce various bioactive compounds, including GABA. The present review aims, after a preliminary excursus on the function and biosynthesis of GABA, to provide an overview of the current uses of microorganisms and, in particular, of L. plantarum in the production of GABA, with a detailed focus on fermented foods. The results of the studies reported in this review highlight that the selection of new probiotic strains of L. plantarum with the ability to synthesize GABA may offer concrete opportunities for the design of new functional foods.

Survival mechanisms of chickpea (Cicer arietinum) under saline conditions

Salinity is a significant abiotic stress that is steadily increasing in intensity globally. Salinity is caused by various factors such as use of poor-quality water for irrigation, poor drainage systems, and increasing spate of drought that concentrates salt solutions in the soil; salinity is responsible for substantial agricultural losses worldwide. Chickpea (Cicer arietinum) is one of the crops most sensitive to salinity stress. Salinity restricts chickpea growth and production by interfering with various physiological and metabolic processes, downregulating genes linked to growth, and upregulating genes encoding intermediates of the tolerance and avoidance mechanisms. Salinity, which also leads to osmotic stress, disturbs the ionic equilibrium of plants. Survival under salinity stress is a primary concern for the plant. Therefore, plants adopt tolerance strategies such as the SOS pathway, antioxidative defense mechanisms, and several other biochemical mechanisms. Simultaneously, affected plants exhibit mechanisms like ion compartmentalization and salt exclusion. In this review, we highlight the impact of salinity in chickpea, strategies employed by the plant to tolerate and avoid salinity, and agricultural strategies for dealing with salinity. With the increasing spate of salinity spurred by natural events and anthropogenic agricultural activities, it is pertinent to explore and exploit the underpinning mechanisms for salinity tolerance to develop mitigation and adaptation strategies in globally important food crops such as chickpea.

Gamma-Aminobutyric Acid Supplementation Boosts the Phytohormonal Profile in 'Candidatus Liberibacter asiaticus'-Infected Citrus

The devastating citrus disease, Huanglongbing (HLB), is associated with 'Candidatus Liberibacter sp.' and transmitted by citrus psyllids. Unfortunately, HLB has no known sustainable cure yet. Herein, we proposed γ-aminobutyric acid (GABA) as a potential eco-friendly therapeutic solution to HLB. Herein, we used GC/MS-based targeted metabolomics combined with gene expression to investigate the role of GABA in citrus response against HLB and to better understand its relationship(s) with different phytohormones. GABA supplementation via root drench boosts the accumulation of endogenous GABA in the leaves of both healthy and 'Ca. L. asiaticus'-infected trees. GABA accumulation benefits the activation of a multi-layered defensive system via modulating the phytohormone levels and regulating the expression of their biosynthesis genes and some pathogenesis-related proteins (PRs) in both healthy and 'Ca. L. asiaticus'-infected plants. Moreover, our findings showed that GABA application stimulates auxin biosynthesis in 'Ca. L. asiaticus'-infected plants via the activation of the indole-3-pyruvate (I3PA) pathway, not via the tryptamine (TAM)-dependent pathway, to enhance the growth of HLB-affected trees. Likewise, GABA accumulation was associated with the upregulation of SA biosynthesis genes, particularly the PAL-dependent route, resulting in higher SA levels that activated CsPR1, CsPR2, CsPR5, and CsWRKY70, which are prominent to activation of the SA-mediated pathway. Additionally, higher GABA levels were correlated with an enhanced JA profile and linked with both CsPR3 and CsPR4, which activates the JA-mediated pathway. Collectively, our findings suggest that exogenous GABA application might be a promising alternative and eco-friendly strategy that helps citrus trees battle HLB.

Salicylic acid treatment and overexpression of a novel polyamine transporter gene for astaxanthin production in Phaffia rhodozyma

Phaffia rhodozyma represents an excellent microbial resource for astaxanthin production. However, the yeast's low astaxanthin productivity poses challenges in scaling up industrial production. Although P. rhodozyma originates from plant material, and phytohormones have demonstrated their effectiveness in stimulating microbial production, there has been limited research on the effects and mechanisms of phytohormones on astaxanthin biosynthesis in P. rhodozyma. In this study, the addition of exogenous salicylic acid (SA) at a concentration as low as 0.5 mg/L significantly enhanced biomass, astaxanthin content, and yield by 20.8%, 95.8% and 135.3% in P. rhodozyma, respectively. Moreover, transcriptomic analysis showed that SA had discernible impact on the gene expression profile of P. rhodozyma cells. Differentially expressed genes (DEGs) in P. rhodozyma cells between the SA-treated and SA-free groups were identified. These genes played crucial roles in various aspects of astaxanthin and its competitive metabolites synthesis, material supply, biomolecule metabolite and transportation, anti-stress response, and global signal transductions. This study proposes a regulatory mechanism for astaxanthin synthesis induced by SA, encompassing the perception and transduction of SA signal, transcription factor-mediated gene expression regulation, and cellular stress responses to SA. Notably, the polyamine transporter gene (PT), identified as an upregulated DEG, was overexpressed in P. rhodozyma to obtain the transformant Prh-PT-006. The biomass, astaxanthin content and yield in this engineered strain could reach 6.6 g/L, 0.35 mg/g DCW and 2.3 mg/L, 24.5%, 143.1% and 199.0% higher than the wild strain at the SA-free condition, respectively. These findings provide valuable insights into potential targets for genetic engineering aimed at achieving high astaxanthin yields, and such advancements hold promise for expediting the industrialization of microbial astaxanthin production.

Epigenetic regulation of neurotransmitter signaling in neurological disorders

Neurotransmission signaling is a highly conserved system attributed to various regulatory events. The excitatory and inhibitory neurotransmitter systems have been extensively studied, and their role in neuronal cell proliferation, synaptogenesis and dendrite formation in the adult brain is well established. Recent research has shown that epigenetic regulation plays a crucial role in mediating the expression of key genes associated with neurotransmitter pathways, including neurotransmitter receptor and transporter genes. The dysregulation of these genes has been linked to a range of neurological disorders such as attention-deficit/hyperactivity disorder, Parkinson's disease and schizophrenia. This article focuses on epigenetic regulatory mechanisms that control the expression of genes associated with four major chemical carriers in the brain: dopamine (DA), Gamma-aminobutyric acid (GABA), glutamate and serotonin. Additionally, we explore how aberrant epigenetic regulation of these genes can contribute to the pathogenesis of relevant neurological disorders. By targeting the epigenetic mechanisms that control neurotransmitter gene expression, there is a promising opportunity to advance the development of more effective treatments for neurological disorders with the potential to significantly improve the quality of life of individuals impacted by these conditions.

Heat stress and excessive maturity of fruiting bodies suppress GABA accumulation by modulating GABA metabolism in Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm

GABA is a health-promoting bioactive substance. Here, the GABA biosynthetic pathways were investigated, and then the dynamic quantitative changes in GABA and the expression levels of genes related to GABA metabolism under heat stress or at different developmental stages of fruiting bodies in Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm were determined. We found that the polyamine degradation pathway was the main route of GABA production under growth normal condition. The accumulation of GABA and the expression of most genes related to GABA biosynthesis, including genes encoding glutamate decarboxylase (PoGAD-2), polyamine oxidase (PoPAO-1), diamine oxidase (PoDAO) and aminoaldehyde dehydrogenase (PoAMADH-1 and PoAMADH-2), were significantly suppressed by heat stress and the excessive maturity of fruiting bodies. Finally, the effects of GABA on the mycelial growth, heat tolerance and the morphogenesis and development of fruiting bodies were studied, the results showed that the deficiency of endogenous GABA inhibited the mycelial growth and primordial formation and aggravated heat damage, whereas exogenous application of GABA could improve thermotolerance and promote the development of fruiting bodies.

Endocytosis of GABA receptor: Signaling in nervous system

GABA (ᵞ-aminobutyric acid), is the principal neurotransmitter known for its inhibitory role in chemical synapses. Being localized primarily in the central nervous system (CNS) it maintains a balance between excitatory (regulated by another neurotransmitter, glutamate) and inhibitory impulses. GABA acts by binding to their specific receptors GABA_A and GABA_B when released into the post-synaptic nerve terminal. Both of these receptors are responsible for fast and slow inhibition of neurotransmission, respectively. GABA_A is a ligand-gated ionopore receptor which opens the Cl^- ion channel and decreases the resting potential of the membrane resulting into inhibition of the synapse. On the other hand, GABA_B is a metabotropic receptor which increases the K⁺ ion levels preventing Ca⁺ ion release inhibiting the release of other neurotransmitters into the presynaptic membrane. The internalization and trafficking of these receptors is also conducted through distinct pathways and mechanism, discussed in detail in the chapter. Without the desired levels of GABA in the body, the psychological and neurological states of brain get hard to maintain. Various neurodegenerative diseases/disorders have been associated to low levels of GABA, such as anxiety, mood disorders, fear, schizophrenia, hungtington's chorea, seizures, epilepsy, etc. The allosteric sites present on GABA receptors have been proved to be potent drug targets to pacify the pathological states of these brain related disorders to an extent. Further in depth studies focussing on the subtypes of GABA receptors and their comprehensive mechanism are required to explore new drug targets and therapeutic avenues for effectual management of GABA related neurological diseases.

Enhancement of γ-aminobutyric acid content in shells of passion fruit (Passiflora edulis) under anoxic vacuum conditions

Passiflora edulis, commonly known as passion fruit, is a popular all-weather fruit eaten fresh or processed. Its shells, which currently are mostly discarded as waste and hurt the environment, account for more than half of the passion fruit. The shells contain gamma-aminobutyric acid (GABA) which is the main inhibitory neurotransmitter and has many proven medical values such as antidepressant, anti-anxiety, etc. Many studies have shown that GABA production in plants can be significantly increased by reverse stress. Taking Tainong 1 as a typical passion fruit cultivar, this study explored the optimal anoxic vacuum treatment for increasing the GABA content of passion fruit shells. The content increased to 2139.25 ± 26.69 mg/100 g on day 4 of chill storage after vacuum packing (63.68% higher than the control). The activities of glutamate decarboxylase (GAD) and diamine oxidase (DAO) were significantly higher in the vacuum-treated group than in the control group after 4 days of vacuum-chill storage. On day 5 of vacuum-chill storage, the activities of all measured enzymes decreased except for the increase of GABA transaminase (GABA-T), which was accompanied by a decrease in GABA content. Vacuum treatment and subsequent chill storage increased the content of GABA, thereby increasing functional value of passion fruit shells.

Secreted immune metabolites that mediate immune cell communication and function

Metabolites are emerging as essential factors for the immune system that are involved in both metabolic circuits and signaling cascades. Accumulated evidence suggests that altered metabolic programs initiated by the activation and maturation of immune cell types are accompanied by the delivery of various metabolites into the local environment. We propose that, in addition to protein/peptide ligands, secreted immune metabolites (SIMets) are essential components of immune communication networks that fine-tune immune responses under homeostatic and pathological conditions. We summarize recent advances in our understanding of SIMets and discuss the potential mechanisms by which some metabolites engage in immunological responses through receptor-, transporter-, and post-translational-mediated regulation. These insights may contribute to understanding physiology and developing effective therapeutics for inflammatory and immune-mediated diseases.

Multispecies transcriptomes reveal core fruit development genes

During angiosperm evolution there have been repeated transitions from an ancestral dry fruit to a derived fleshy fruit, often with dramatic ecological and economic consequences. Following the transition to fleshy fruits, domestication may also dramatically alter the fruit phenotype via artificial selection. Although the morphologies of these fruits are well documented, relatively less is known about the molecular basis of these developmental and evolutionary shifts. We generated RNA-seq libraries from pericarp tissue of desert tobacco and both cultivated and wild tomato species at common developmental time points and combined this with corresponding, publicly available data from Arabidopsis and melon. With this broadly sampled dataset consisting of dry/fleshy fruits and wild/domesticated species, we applied novel bioinformatic methods to investigate conserved and divergent patterns of gene expression during fruit development and evolution. A small set of 121 orthologous "core" fruit development genes show a common pattern of expression across all five species. These include key players in developmental patterning such as orthologs of KNOLLE, PERIANTHIA, and ARGONAUTE7. GO term enrichment suggests that these genes function in basic cell division processes, cell wall biosynthesis, and developmental patterning. We furthermore uncovered a number of "accessory" genes with conserved expression patterns within but not among fruit types, and whose functional enrichment highlights the conspicuous differences between these phenotypic classes. We observe striking conservation of gene expression patterns despite large evolutionary distances, and dramatic phenotypic shifts, suggesting a conserved function for a small subset of core fruit development genes.

Picrotoxin Delineates Different Transport Configurations for Malate and γ Aminobutyric Acid through TaALMT1

Plant-derived pharmacological agents have been used extensively to dissect the structure–function relationships of mammalian GABA receptors and ion channels. Picrotoxin is a non-competitive antagonist of mammalian GABAA receptors. Here, we report that picrotoxin inhibits the anion (malate) efflux mediated by wheat (Triticum aestivum) ALMT1 but has no effect on GABA transport. The EC50 for inhibition was 0.14 nM and 0.18 nM when the ALMTs were expressed in tobacco BY2 cells and in Xenopus oocytes, respectively. Patch clamping of the oocyte plasma membrane expressing wheat ALMT1 showed that picrotoxin inhibited malate currents from both sides of the membrane. These results demonstrate that picrotoxin inhibits anion efflux effectively and can be used as a new inhibitor to study the ion fluxes mediated by ALMT proteins that allow either GABA or anion transport.

Metabolomic Analysis Reveals Changes of Bioactive Compounds in Mung Beans (Vigna radiata) during γ-Aminobutyric Acid Enrichment Treatment

Soaking together with Heat and Relative Humidity (HRH) treatment has been applied successfully to enrich γ-aminobutyric acid (GABA) in mung beans. However, whether and how the above GABA enrichment processing influences the other bioactive molecules is elusive. In the present study, mung beans were soaked and then treated by HRH for 5 or 7 h. By using metabolomics techniques, the changes of 496 metabolites were determined. The relative content of flavonoids and phenolic acids increased during soaking but slightly decreased during HRH. Intriguingly, soaking and HRH had the opposite effects on the glycosylation of polyphenols. The relative content of glycosylated or un-glycosylated polyphenols increased during soaking or HRH, respectively. The relative content of α-ketoglutaric acid increased more than 20 times after 5 h HRH treatment. Bioactive molecules could be enriched during GABA enrichment processing. Depending on the desired bioactive compounds, soaking and different duration of HRH treatment could be selected.

Metabolite Profiling of Chestnut (Castanea crenata) According to Origin and Harvest Time Using 1H NMR Spectroscopy

Chestnuts are an important food crop commonly used as a food ingredient due to their nutritional properties and potential health benefits. In Korea, chestnuts have been crossbred to develop cultivars with insect resistance and high productivity, producing multiple chestnut varieties. This study classified 17 Castanea crenata cultivars produced in Korea according to origin and harvest time and determined the metabolites in chestnut kernels using ¹H nuclear magnetic resonance spectroscopy. The 17 C. crenata cultivars were divided into four groups based on their geographic origin: Korean native, Korean hybrid, Japanese native, and Japanese hybrid. The cultivars were also divided into three groups depending on their harvest period: early-ripening cultivar, mid-ripening cultivar, and late-ripening cultivar. The partial least squares-discriminant analysis score plot revealed differences among the groups. Identified metabolites, including amino acids, organic acids, and sugars, contributed to discriminating the origin and harvest time of the C. crenata chestnut kernels. Significant differences were observed, mainly in amino acids, which suggests that the composition of amino acids is one factor influenced by both the origin and harvest time of C. crenata. These results are useful to both growers and breeders because they identify the nutritional and metabolic characteristics of each C. crenata cultivar.

Polyamines Metabolism Interacts with γ-Aminobutyric Acid, Proline and Nitrogen Metabolisms to Affect Drought Tolerance of Creeping Bentgrass

Due to increased global warming and climate change, drought has become a serious threat to horticultural crop cultivation and management. The purpose of this study was to investigate the effect of spermine (Spm) pretreatment on metabolic alterations of polyamine (PAs), γ-aminobutyric acid (GABA), proline (Pro), and nitrogen associated with drought tolerance in creeping bentgrass (Agrostis stolonifera). The results showed that drought tolerance of creeping bentgrass could be significantly improved by the Spm pretreatment, as demonstrated by the maintenance of less chlorophyll loss and higher photosynthesis, gas exchange, water use efficiency, and cell membrane stability. The Spm pretreatment further increased drought-induced accumulation of endogenous PAs, putrescine, spermidine, and Spm, and also enhanced PAs metabolism through improving arginine decarboxylases, ornithine decarboxylase, S-adenosylmethionine decarboxylase, and polyamine oxidase activities during drought stress. In addition, the Spm application not only significantly improved endogenous GABA content, glutamate content, activities of glutamate decarboxylase and α-ketoglutarase, but also alleviated decline in nitrite nitrogen content, nitrate reductase, glutamine synthetase, glutamate synthetase, and GABA aminotransferase activities under drought stress. The Spm-pretreated creeping bentgrass exhibited significantly lower ammonia nitrogen content and nitrite reductase activity as well as higher glutamate dehydrogenase activity than non-pretreated plants in response to drought stress. These results indicated beneficial roles of the Spm on regulating GABA and nitrogen metabolism contributing towards better maintenance of Tricarboxylic acid (TCA) cycle in creeping bentgrass. Interestingly, the Spm-enhanced Pro metabolism rather than more Pro accumulation could be the key regulatory mechanism for drought tolerance in creeping bentgrass. Current findings provide a comprehensive understanding of PAs interaction with other metabolic pathways to regulate drought tolerance in grass species.

General anesthesia bullies the gut: a toxic relationship with dysbiosis and cognitive dysfunction

Perioperative neurocognitive disorder (PND) is a common surgery outcome affecting up to a third of the elderly patients, and it is associated with high morbidity and increased risk for Alzheimer's disease development. PND is characterized by cognitive impairment that can manifest acutely in the form of postoperative delirium (POD) or after hospital discharge as postoperative cognitive dysfunction (POCD). Although POD and POCD are clinically distinct, their development seems to be mediated by a systemic inflammatory reaction triggered by surgical trauma that leads to dysfunction of the blood-brain barrier and facilitates the occurrence of neuroinflammation. Recent studies have suggested that the gut microbiota composition may play a pivotal role in the PND development by modulating the risk of neuroinflammation establishment. In fact, modulation of gut microbiome composition with pre- and probiotics seems to be effective for the prevention and treatment of PND in animals. Interestingly, general anesthetics seem to have major responsibility on the gut microbiota composition changes following surgery and, consequently, can be an important element in the process of PND initiation. This concept represents an important milestone for the understanding of PND pathogenesis and may unveil new opportunities for the development of preventive or mitigatory strategies against the development of these conditions. The aim of this review is to discuss how anesthetics used in general anesthesia can interact and alter the gut microbiome composition and contribute to PND development by favoring the emergence of neuroinflammation.

Not Just a Cycle: Three gab Genes Enable the Non-Cyclic Flux Toward Succinate via GABA Shunt in 'Candidatus Liberibacter asiaticus'-Infected Citrus

Although the mitochondria retain all required enzymes for an intact tricarboxylic acid (TCA) cycle, plants might shift the cyclic flux from the TCA cycle to an alternative noncyclic pathway via γ-aminobutyric acid (GABA) shunt under specific physiological conditions. We hypothesize that several genes may ease this noncyclic flux and contribute to the citrus response to the phytopathogenic bacterium 'Candidatus Liberibacter asiaticus', the causal agent of Huanglongbing in citrus. To test this hypothesis, we used multiomics techniques (metabolomics, fluxomics, and transcriptomics) to investigate the potential roles of putative gab homologies from Valencia sweet orange (Citrus sinensis). Our findings showed that 'Ca. L. asiaticus' significantly increased the endogenous GABA and succinate content but decreased ketoglutarate in infected citrus plants. Citrus genome harbors three putative gab genes, including amino-acid permease (also known as GABA permease; CsgabP), GABA transaminase (CsgabT), and succinate-semialdehyde dehydrogenase (also known as GABA dehydrogenase; CsgabD). The transcript levels of CsgabP, CsgabT, and CsgabD were upregulated in citrus leaves upon the infection with 'Ca. L. asiaticus' and after the exogenous application of GABA or deuterium-labeled GABA isotope (GABA-D₆). Moreover, our finding showed that exogenously applied GABA is quickly converted to succinate and fed into the TCA cycle. Likewise, the fluxomics study showed that GABA-D₆ is rapidly metabolized to succinate-D₄. Our work proved that GABA shunt and three predicated gab genes from citrus, support the upstream noncyclic flux toward succinate rather than an intact TCA cycle and contribute to citrus defense responses to 'Ca. L. asiaticus'.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Evaluation of Associated Genes with Traumatic Pain: A Systematic Review

OBJECTIVES

The knowledge about the molecular pathway of traumatic pain relief is less documented. This systematic review study aimed to identify the genes and molecular pathways associated with various traumatic pains.

METHODS

The online databases such as EMBASE, MEDLINE, PubMed, Cochrane Library, International Clinical Trials Registry Platform, Clinical Trials, Google Scholar, Wiley, ISI Web of Knowledge, and Scopus were searched. Two review authors searched and screened all records' titles and abstracts, and the third expert reviewer author resolved their disagreement. The study's design, various trauma injuries, types of genes, and molecular pathways were recorded. The genes and molecular pathways data were obtained via GeneCards®: The Human Gene Database (https://www.genecards.org).

RESULTS

Studies on a variety of trauma injuries regarding nerve and Spinal Cord Injuries (SCIs) (12 records), Hypertrophic scar with Severe Pain (one record), severe post-traumatic musculoskeletal pain (MSP) (one record), and orthopedic trauma (one record) were included. The main molecular pathways such as the immune system, apoptosis, and death receptor signaling, T-cell antigen receptor (TCR) signaling pathway, oxidative stress, interleukin(s) mediated signaling pathway, biological oxidations, metabolic pathways (especially amino acid metabolism and amino group), focal adhesion, the proliferation of vascular, epithelial, and connective tissue cells, angiogenesis and neural development were identified.

CONCLUSION

The immune system, apoptosis, and metabolic pathways are crucial for understanding the roles of genes in traumatic pain. It is recommended that these identified pathways and related genes be considered therapeutical targets for pain management in patients with trauma injuries. In addition, different forms of trauma injuries require different pathways and related genes to be considered.

The emerging role of GABA as a transport regulator and physiological signal

While the proposal that γ-aminobutyric acid (GABA) acts a signal in plants is decades old, a signaling mode of action for plant GABA has been unveiled only relatively recently. Here, we review the recent research that demonstrates how GABA regulates anion transport through aluminum-activated malate transporters (ALMTs) and speculation that GABA also targets other proteins. The ALMT family of anion channels modulates multiple physiological processes in plants, with many members still to be characterized, opening up the possibility that GABA has broad regulatory roles in plants. We focus on the role of GABA in regulating pollen tube growth and stomatal pore aperture, and we speculate on its role in long-distance signaling and how it might be involved in cross talk with hormonal signals. We show that in barley (Hordeum vulgare), guard cell opening is regulated by GABA, as it is in Arabidopsis (Arabidopsis thaliana), to regulate water use efficiency, which impacts drought tolerance. We also discuss the links between glutamate and GABA in generating signals in plants, particularly related to pollen tube growth, wounding, and long-distance electrical signaling, and explore potential interactions of GABA signals with hormones, such as abscisic acid, jasmonic acid, and ethylene. We conclude by postulating that GABA encodes a signal that links plant primary metabolism to physiological status to fine tune plant responses to the environment.

Emerging Roles of γ Aminobutyric Acid (GABA) Gated Channels in Plant Stress Tolerance

The signaling role for γ-Aminobutyric acid (GABA) has been documented in animals for over seven decades. However, a signaling role for GABA in plants is just beginning to emerge with the discovery of putative GABA binding site/s and GABA regulation of anion channels. In this review, we explore the role of GABA in plant growth and development under abiotic stress, its interactions with other signaling molecules and the probability that there are other anion channels with important roles in stress tolerance that are gated by GABA.

γ-Aminobutyrate (GABA) Regulated Plant Defense: Mechanisms and Opportunities

Global climate change and associated adverse abiotic and biotic stress conditions affect plant growth and development, and agricultural sustainability in general. Abiotic and biotic stresses reduce respiration and associated energy generation in mitochondria, resulting in the elevated production of reactive oxygen species (ROS), which are employed to transmit cellular signaling information in response to the changing conditions. Excessive ROS accumulation can contribute to cell damage and death. Production of the non-protein amino acid γ-aminobutyrate (GABA) is also stimulated, resulting in partial restoration of respiratory processes and energy production. Accumulated GABA can bind directly to the aluminum-activated malate transporter and the guard cell outward rectifying K+ channel, thereby improving drought and hypoxia tolerance, respectively. Genetic manipulation of GABA metabolism and receptors, respectively, reveal positive relationships between GABA levels and abiotic/biotic stress tolerance, and between malate efflux from the root and heavy metal tolerance. The application of exogenous GABA is associated with lower ROS levels, enhanced membrane stability, changes in the levels of non-enzymatic and enzymatic antioxidants, and crosstalk among phytohormones. Exogenous GABA may be an effective and sustainable tolerance strategy against multiple stresses under field conditions.

Potential Roles for Gamma-Aminobutyric Acid Signaling in Bacterial Communities

It is now established that the gut microbiome influences human neurology and behavior, and vice versa. Distinct mechanisms underlying this bidirectional communication pathway, termed the gut-brain axis, are becoming increasingly uncovered. This review summarizes recent interkingdom signaling research focused on gamma-aminobutyric acid (GABA), a human neurotransmitter and ubiquitous signaling molecule found in bacteria, fungi, plants, invertebrates, and mammals. We detail how GABAergic signaling has been shown to be a crucial component of the gut-brain axis. We further describe how GABA is also being found to mediate interkingdom signaling between algae and invertebrates, plants and invertebrates, and plants and bacteria. Based on these emerging results, we argue that obtaining a complete understanding of GABA-mediated communication in the gut-brain axis will involve deciphering the role of GABA signaling and metabolism within bacterial communities themselves.

GABA signalling modulates stomatal opening to enhance plant water use efficiency and drought resilience

The non-protein amino acid γ-aminobutyric acid (GABA) has been proposed to be an ancient messenger for cellular communication conserved across biological kingdoms. GABA has well-defined signalling roles in animals; however, whilst GABA accumulates in plants under stress it has not been determined if, how, where and when GABA acts as an endogenous plant signalling molecule. Here, we establish endogenous GABA as a bona fide plant signal, acting via a mechanism not found in animals. Using Arabidopsis thaliana, we show guard cell GABA production is necessary and sufficient to reduce stomatal opening and transpirational water loss, which improves water use efficiency and drought tolerance, via negative regulation of a stomatal guard cell tonoplast-localised anion transporter. We find GABA modulation of stomata occurs in multiple plants, including dicot and monocot crops. This study highlights a role for GABA metabolism in fine tuning physiology and opens alternative avenues for improving plant stress resilience.

Priming with γ-Aminobutyric Acid against Botrytis cinerea Reshuffles Metabolism and Reactive Oxygen Species: Dissecting Signalling and Metabolism

The stress-inducible non-proteinogenic amino acid γ-aminobutyric acid (GABA) is known to alleviate several (a)biotic stresses in plants. GABA forms an important link between carbon and nitrogen metabolism and has been proposed as a signalling molecule in plants. Here, we set out to establish GABA as a priming compound against Botrytis cinerea in Arabidopsis thaliana and how metabolism and reactive oxygen species (ROS) are influenced after GABA treatment and infection. We show that GABA already primes disease resistance at low concentrations (100 µM), comparable to the well-characterized priming agent β-Aminobutyric acid (BABA). Treatment with GABA reduced ROS burst in response to flg22 (bacterial peptide derived from flagellum) and oligogalacturonides (OGs). Plants treated with GABA showed reduced H₂O₂ accumulation after infection due to increased activity of catalase and guaiacol peroxidase. Contrary to 100 µM GABA treatments, 1 mM exogenous GABA induced endogenous GABA before and after infection. Strikingly, 1 mM GABA promoted total and active nitrate reductase activity whereas 100 µM inhibited active nitrate reductase. Sucrose accumulated after GABA treatment, whereas glucose and fructose only accumulated in treated plants after infection. We propose that extracellular GABA signalling and endogenous metabolism can be separated at low exogenous concentrations.

A Targeted Bioinformatics Assessment of Adrenocortical Carcinoma Reveals Prognostic Implications of GABA System Gene Expression

Adrenocortical carcinoma (ACC) is a rare but deadly cancer for which few treatments exist. Here, we have undertaken a targeted bioinformatics study of The Cancer Genome Atlas (TCGA) ACC dataset focusing on the 30 genes encoding the γ-aminobutyric acid (GABA) system—an under-studied, evolutionarily-conserved system that is an emerging potential player in cancer progression. Our analysis identified a subset of ACC patients whose tumors expressed a distinct GABA system transcriptome. Transcript levels of ABAT (encoding a key GABA shunt enzyme), were upregulated in over 40% of tumors, and this correlated with several favorable clinical outcomes including patient survival; while enrichment and ontology analysis implicated two cancer-related biological pathways involved in metastasis and immune response. The phenotype associated with ABAT upregulation revealed a potential metabolic heterogeneity among ACC tumors associated with enhanced mitochondrial metabolism. Furthermore, many GABA_A receptor subunit-encoding transcripts were expressed, including two (GABRB2 and GABRD) prognostic for patient survival. Transcripts encoding GABA_B receptor subunits and GABA transporters were also ubiquitously expressed. The GABA system transcriptome of ACC tumors is largely mirrored in the ACC NCI-H295R cell line, suggesting that this cell line may be appropriate for future functional studies investigating the role of the GABA system in ACC cell growth phenotypes and metabolism.

Induction of γ-aminobutyric acid plays a positive role to Arabidopsis resistance against Pseudomonas syringae

Gamma-aminobutyric acid (GABA) is an important metabolite which functions in plant growth, development, and stress responses. However, its role in plant defense and how it is regulated are largely unknown. Here, we report a detailed analysis of GABA induction during the resistance response to Pseudomonas syringae in Arabidopsis thaliana. While searching for the mechanism underlying the pathogen-responsive mitogen-activated protein kinase (MPK)3/MPK6 signaling cascade in plant immunity, we found that activation of MPK3/MPK6 greatly induced GABA biosynthesis, which is dependent on the glutamate decarboxylase genes GAD1 and GAD4. Inoculation with Pseudomonas syringae pv tomato DC3000 (Pst) and Pst-avrRpt2 expressing the avrRpt2 effector gene induced GAD1 and GAD4 gene expression and increased the levels of GABA. Genetic evidence revealed that GAD1, GAD2, and GAD4 play important roles in both GABA biosynthesis and plant resistance in response to Pst-avrRpt2 infection. The gad1/2/4 triple and gad1/2/4/5 quadruple mutants, in which the GABA levels were extremely low, were more susceptible to both Pst and Pst-avrRpt2. Functional loss of MPK3/MPK6, or their upstream MKK4/MKK5, or their downstream substrate WRKY33 suppressed the induction of GAD1 and GAD4 expression after Pst-avrRpt2 treatment. Our findings shed light on both the regulation and role of GABA in the plant immunity to a bacterial pathogen.

GABA signaling in plants: targeting the missing pieces of the puzzle

The adaptation of plants to unstable environments relies on their ability to sense their surroundings and to generate and transmit corresponding signals to different parts of the plant to evoke changes necessary for optimizing growth and defense. Plants, like animals, contain a huge repertoire of intra- and intercellular signals, including organic and inorganic molecules. The occurrence of neurotransmitter-like signaling molecules in plants has been an intriguing field of research. Among these, γ-aminobutyric acid (GABA) was discovered in plants over half a century ago, and studies of its roles as a primary metabolite have been well documented, particularly in the context of stress responses. In contrast, evidence of the potential mechanism by which GABA acts as a signaling molecule in plants has only recently been reported. In spite of this breakthrough, the roles of GABA as a signaling molecule in plants have yet to be established and several aspects of the complexity of the GABA signaling system remain obscure. This review summarizes the uncertainties in GABA signaling in plants and suggests research directions and technologies that would help in answering unsolved questions.

Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review

Gamma-aminobutyric acid (GABA) is a non-proteinogenic amino acid and is the main inhibitory neurotransmitter in the mammalian brain. GABA's stress-reducing, and sleep enhancing effects have been established. However, although several human clinical trials have been conducted, results regarding the role of natural and/or biosynthetic oral GABA intake on stress and sleep are mixed. We performed a systematic review to examine whether natural and/or biosynthetic oral GABA intake has an effect on stress and sleep. We systematically searched on PubMed database for studies published up to February 2020 following PRISMA guidelines. Only placebo-controlled human trials that assessed stress, sleep, and related psychophysiological outcomes as a response to natural GABA (i.e., GABA that is present naturally in foods) or biosynthetic GABA (i.e., GABA that is produced via fermentation) intake were included. Fourteen studies met the criteria and were included in the systematic review. Although more studies are needed before any inferences can be made about the efficacy of oral GABA consumption on stress and sleep, results show that there is limited evidence for stress and very limited evidence for sleep benefits of oral GABA intake.

Dialog between skin and its microbiota: Emergence of "Cutaneous Bacterial Endocrinology"

Microbial endocrinology is studying the response of microorganisms to hormones and neurohormones and the microbiota production of hormones-like molecules. Until now, it was mainly applied to the gut and revealed that the intestinal microbiota should be considered as a real organ in constant and bilateral interactions with the whole human body. The skin harbours the second most abundant microbiome and contains an abundance of nerve terminals and capillaries, which in addition to keratinocytes, fibroblasts, melanocytes, dendritic cells and endothelial cells, release a huge diversity of hormones and neurohormones. In the present review, we will examine recent experimental data showing that, in skin, molecules such as substance P, calcitonin gene-related peptide, natriuretic peptides and catecholamines can directly affect the physiology and virulence of common skin-associated bacteria. Conversely, bacteria are able to synthesize and release compounds including histamine, glutamate and γ-aminobutyric acid or peptides showing partial homology with neurohormones such as α-melanocyte-stimulating hormone (αMSH). The more surprising is that some viruses can also encode neurohormones mimicking proteins. Taken together, these elements demonstrate that there is also a cutaneous microbial endocrinology and this emerging concept will certainly have important consequences in dermatology.

Dietary GABA induces endogenous synthesis of a novel imidazole peptide homocarnosine in mouse skeletal muscles

Carnosine (β-alanyl-L-histidine) is an imidazole dipeptide present at high concentrations in skeletal muscles, where it plays a beneficial role. However, oral intake of carnosine or β-alanine to increase skeletal muscle carnosine levels has disadvantages such as low efficiency and side effects. Therefore, we proposed homocarnosine (γ-aminobutyryl-L-histidine) as a novel alternative imidazole peptide for skeletal muscle based on its structural similarity to carnosine. To induce endogenous homocarnosine synthesis in skeletal muscles, mice were fed a basal diet mixed with 0, 0.5, 2, or 5% γ-aminobutyric acid (GABA) for 6 weeks. As expected, in the control group (0% GABA), GABA and homocarnosine were present in trace concentrations. Skeletal muscle homocarnosine levels were significantly increased in the 2% and 5% GABA intake groups (tenfold, P < 0.01 and 53-fold, P < 0.01; respectively) relative to those of the control group, whereas 0.5% GABA intake induced no such effect. GABA intake had no effect on the levels of carnosine, anserine, and β-alanine. Vigabatrin (inhibitor of GABA transaminase (GABA-T)) administration to mice receiving 2% GABA intake for 2 weeks led to GABA-T inhibition in the liver. Subsequently, a 43-fold increase in circulating GABA levels and a tendency increase in skeletal muscle homocarnosine levels were observed. Therefore, skeletal muscle homocarnosine synthesis can be induced by supplying its substrate GABA in tissues. As GABA availability is tightly regulated by GABA-T via GABA degradation, inhibitors of GABA or β-alanine degradation could be novel potential interventions for increasing skeletal muscle imidazole dipeptides.

Correlation-based network analysis combined with machine learning techniques highlight the role of the GABA shunt in Brachypodium sylvaticum freezing tolerance

Perennial grasses will account for approximately 16 billion gallons of renewable fuels by the year 2022, contributing significantly to carbon and nitrogen sequestration. However, perennial grasses productivity can be limited by severe freezing conditions in some geographical areas, although these risks could decrease with the advance of climate warming, the possibility of unpredictable early cold events cannot be discarded. We conducted a study on the model perennial grass Brachypodium sylvaticum to investigate the molecular mechanisms that contribute to cold and freezing adaption. The study was performed on two different B. sylvaticum accessions, Ain1 and Osl1, typical to warm and cold climates, respectively. Both accessions were grown under controlled conditions with subsequent cold acclimation followed by freezing stress. For each treatment a set of morphological parameters, transcription, metabolite, and lipid profiles were measured. State-of-the-art algorithms were employed to analyze cross-component relationships. Phenotypic analysis revealed higher adaption of Osl1 to freezing stress. Our analysis highlighted the differential regulation of the TCA cycle and the GABA shunt between Ain1 and Osl1. Osl1 adapted to freezing stress by repressing the GABA shunt activity, avoiding the detrimental reduction in fatty acid biosynthesis and the concomitant detrimental effects on membrane integrity.

"Help is in the air": volatiles from salt-stressed plants increase the reproductive success of receivers under salinity

Salinity alters VOC profile in emitter sweet basil plants. Airborne signals by emitter plants promote earlier flowering of receivers and increase their reproductive success under salinity. Airborne signals can prime neighboring plants against pathogen and/or herbivore attacks, whilst little is known about the possibility that volatile organic compounds (VOCs) emitted by stressed plants alert neighboring plants against abiotic stressors. Salt stress (50 mM NaCl) was imposed on Ocimum basilicum L. plants (emitters, namely NaCl), and a putative alerting-priming interaction was tested on neighboring basil plants (receivers, namely NaCl-S). Compared with the receivers, the NaCl plants exhibited reduced biomass, lower photosynthesis, and changes in the VOC profile, which are common early responses of plants to salinity. In contrast, NaCl-S plants had physiological parameters similar to those of nonsalted plants (C), but exhibited a different VOC fingerprint, which overlapped, for most compounds, with that of emitters. NaCl-S plants exposed later to NaCl treatment (namely NaCl-S + NaCl) exhibited changes in the VOC profile, earlier plant senescence, earlier flowering, and higher seed yield than C + NaCl plants. This experiment offers the evidence that (1) NaCl-triggered VOCs promote metabolic changes in NaCl-S plants, which, finally, increase reproductive success and (2) the differences in VOC profiles observed between emitters and receivers subjected to salinity raise the question whether the receivers are able to "propagate" the warning signal triggered by VOCs in neighboring companions.

Extra-mitochondrial citrate synthase initiates calcium oscillation and suppresses age-dependent sperm dysfunction

Men and women become infertile with age, but the mechanism of declining male fertility, more specifically, the decrease in in sperm quality, is not well known. Citrate synthase (CS) is a core enzyme of the mitochondrial tricarboxylic acid (TCA) cycle, which directly controls cellular function. Extra-mitochondrial CS (eCS) is produced and abundant in the sperm head; however, its role in male fertility is unknown. We investigated the role of eCS in male fertility by producing eCs-deficient (eCs-KO) mice. The initiation of the first spike of Ca²⁺ oscillation was substantially delayed in egg fused with eCs-KO sperm, despite normal expression of sperm factor phospholipase C zeta 1. The eCs-KO male mice were initially fertile, but the fertility dropped with age. Metabolomic analysis of aged sperm revealed that the loss of eCS enhances TCA cycle in the mitochondria with age, presumably leading to depletion of extra-mitochondrial citrate. The data suggest that eCS suppresses age-dependent male infertility, providing insights into the decline of male fertility with age.

Assessment of the effects of metribuzin, glyphosate, and their mixtures on the metabolism of the model plant Lemna minor L. applying metabolomics

Chemical plant protection products (PPPs) is a major group of xenobiotics that are being released in the environment. Although the effects of individual active ingredients (a.i.) on organisms have been studied, information on those of mixtures, is fragmented. Aquatic environments are being polluted by PPPs, posing serious risks for the environment, human, and other organisms. Based on the potential of the model aquatic plant Lemna minor L. in the assessment of PPPs-caused stresses, we have undertaken the task of developing a metabolomics approach for the study of the effects of metribuzin and glyphosate, and their mixtures. Bioassays revealed that metribuzin exhibit higher toxicity than glyphosate and metabolomics highlighted corresponding changes in its metabolome. Treatments had a substantial impact on plants' amino acid pool, resulting in elevated levels of the majority of the identified amino acids. Results indicate that the increased proteolytic activity is a common effect of the a.i. and their mixtures. Additionally, the activation of salicylate-signaling pathways was recorded as a response to the toxicity caused by mixtures. Among the identified metabolites that were discovered as biomarkers were γ-aminobutyric acid (GABA), salicylate, caffeate, α,α-trehalose, and squalene, which play multiple roles in plants' metabolism such as, signaling, antioxidant, and structure protection. No reports exist on the combined effects of PPPs on Lemna and results confirm the applicability of Lemna metabolomics in the study of the combined effects of herbicides and its potential in the monitoring of the environmental health of aquatic environments based on fluctuations of the plant's metabolism.

Analysis of metabolomics associated with quality differences between room-temperature- and low-temperature-stored litchi pulps

Studies on how temperature affects the postharvest quality of litchi have focused mainly on pericarp browning but rarely on the metabolites in postharvest litchi pulp. In this study, the differences in respiration rates, total soluble solid content, and titratable acid content demonstrated that room and low temperatures have different effects on the quality of "Feizixiao" litchi pulp. UHPLC-ESI-QTOF-MS/MS analysis was performed to compare the differentially expressed metabolites (DEMs) in litchi pulp after 8 days of storage at room temperature (RT-8 d) with those in litchi pulp after 28 days of storage at low temperature (LT-28 d). Nineteen carbohydrates (phosphohexoses, sorbitol, and mannose), fifteen acids, seven amino acids, nine energy metabolites and nucleotides, and six aliphatic and secondary metabolites were identified as common DEMs in RT-8 d and LT-28 d pulps. These findings indicated active fructose and mannose metabolism and increased catabolism of nicotinate, nicotinamide, alanine, aspartate, and glutamate. Four carbohydrates (mainly phosphohexoses), five acids, ten amino acids, three aliphatic and secondary metabolites, and one hormone were identified as unique DEMs in RT-8 d pulp, the consumption of key metabolites in glycolysis and the tricarboxylic acid cycle, and accumulation of phenylalanine, tyrosine, and tryptophan. Active consumption of nucleotide metabolites and biosynthesis of aliphatics in LT-28 d pulp were indicated by unique DEMs (eleven carbohydrates, four acids, seven amino acids, seven energy metabolites and nucleotides, and six aliphatic and secondary metabolites). These results provided an unambiguous metabolic fingerprint, thereby revealing how room and low temperatures differentially influenced the quality of litchi pulp.

Origin and Evolution of the Neuroendocrine Control of Reproduction in Vertebrates, With Special Focus on Genome and Gene Duplications

In humans, as in the other mammals, the neuroendocrine control of reproduction is ensured by the brain-pituitary gonadotropic axis. Multiple internal and environmental cues are integrated via brain neuronal networks, ultimately leading to the modulation of the activity of gonadotropin-releasing hormone (GnRH) neurons. The decapeptide GnRH is released into the hypothalamic-hypophysial portal blood system and stimulates the production of pituitary glycoprotein hormones, the two gonadotropins luteinizing hormone and follicle-stimulating hormone. A novel actor, the neuropeptide kisspeptin, acting upstream of GnRH, has attracted increasing attention in recent years. Other neuropeptides, such as gonadotropin-inhibiting hormone/RF-amide related peptide, and other members of the RF-amide peptide superfamily, as well as various nonpeptidic neuromediators such as dopamine and serotonin also provide a large panel of stimulatory or inhibitory regulators. This paper addresses the origin and evolution of the vertebrate gonadotropic axis. Brain-pituitary neuroendocrine axes are typical of vertebrates, the pituitary gland, mediator and amplifier of brain control on peripheral organs, being a vertebrate innovation. The paper reviews, from molecular and functional perspectives, the evolution across vertebrate radiation of some key actors of the vertebrate neuroendocrine control of reproduction and traces back their origin along the vertebrate lineage and in other metazoa before the emergence of vertebrates. A focus is given on how gene duplications, resulting from either local events or from whole genome duplication events, and followed by paralogous gene loss or conservation, might have shaped the evolutionary scenarios of current families of key actors of the gonadotropic axis.

A magnetic affinity approach to identify plant GABA-binding proteins

In plants, GABA plays a critical role in sexual plant reproduction; however, GABA receptors and the associated detailed signaling mechanisms remain to be elucidated. Our experiments show that the proposed technique is reliable and convenient for probing GABA-binding proteins and could be applicable in similar projects by covalently immobilizing the free carboxylic group of GABA on magnetic beads (SiMAG-Carboxyl). New probes produced by covalently immobilizing the free carboxylic group of GABA on magnetic beads (SiMAG-Carboxyl) can obtain useful information on GABA receptors in plants.

Enhancing Haematococcus pluvialis biomass and γ-aminobutyric acid accumulation by two-step cultivation and salt supplementation

The primary goal of this study was to assess the roles of chemical factors and bioprocess strategies on a mixotrophic culture of the microalga Haematococcus pluvialis during γ-aminobutyric acid (GABA) production. A two-stage strategy was used to increase the biomass and GABA accumulation of H. pluvialis. In stage I, mixotrophic growth of H. pluvialis in the presence of fulvic acid (FA) produced a high biomass (1.84 g L^-1) with a GABA content of 25.45 mg g^-1. Furthermore, a maximum GABA content of 38.57 mg g^-1 was obtained when cells were cultured with 0.4 g L^-1 NaCl under photoautotrophic conditions in stage II, whereas the carbohydrate content of cells sharply decreased from 26.68 to 18.22%. In addition, salt stress upregulated the expression of the gad and cam genes. The results of this study demonstrate an efficient strategy to produce GABA from the microalga H. pluvialis.

Monoamine Biosynthesis via a Noncanonical Calcium-Activatable Aromatic Amino Acid Decarboxylase in Psilocybin Mushroom

Aromatic l-amino acid decarboxylases (AAADs) are a phylogenetically diverse group of enzymes responsible for the decarboxylation of aromatic amino acid substrates into their corresponding aromatic arylalkylamines. AAADs have been extensively studied in mammals and plants as they catalyze the first step in the production of neurotransmitters and bioactive phytochemicals, respectively. Unlike mammals and plants, the hallucinogenic psilocybin mushroom Psilocybe cubensis reportedly employs an unrelated phosphatidylserine-decarboxylase-like enzyme to catalyze l-tryptophan decarboxylation, the first step in psilocybin biosynthesis. To explore the origin of this chemistry in psilocybin mushroom, we generated the first de novo transcriptomes of P. cubensis and investigated several putative l-tryptophan-decarboxylase-like enzymes. We report the biochemical characterization of a noncanonical AAAD from P. cubensis ( PcncAAAD) that exhibits substrate permissiveness toward l-phenylalanine, l-tyrosine, and l-tryptophan, as well as chloro-tryptophan derivatives. The crystal structure of PcncAAAD revealed the presence of a unique C-terminal appendage domain featuring a novel double-β-barrel fold. This domain is required for PcncAAAD activity and regulates catalytic rate and thermal stability through calcium binding. PcncAAAD likely plays a role in psilocybin production in P. cubensis and offers a new tool for metabolic engineering of aromatic-amino-acid-derived natural products.

Fruit Decay to Diseases: Can Induced Resistance and Priming Help?

Humanity faces the challenge of having to increase food production to feed an exponentially growing world population, while crop diseases reduce yields to levels that we can no longer afford. Besides, a significant amount of waste is produced after fruit harvest. Fruit decay due to diseases at a post-harvest level can claim up to 50% of the total production worldwide. Currently, the most effective means of disease control is the use of pesticides. However, their use post-harvest is extremely limited due to toxicity. The last few decades have witnessed the development of safer methods of disease control post-harvest. They have all been included in programs with the aim of achieving integrated pest (and disease) management (IPM) to reduce pesticide use to a minimum. Unfortunately, these approaches have failed to provide robust solutions. Therefore, it is necessary to develop alternative strategies that would result in effective control. Exploiting the immune capacity of plants has been described as a plausible route to prevent diseases post-harvest. Post-harvest-induced resistance (IR) through the use of safer chemicals from biological origin, biocontrol, and physical means has also been reported. In this review, we summarize the successful activity of these different strategies and explore the mechanisms behind. We further explore the concept of priming, and how its long-lasting and broad-spectrum nature could contribute to fruit resistance.

Enhanced accumulation of gamma-aminobutyric acid in rice bran using anaerobic incubation with various additives

An anaerobic incubation for the enzymatic production of gamma-aminobutyric acid (GABA) in rice bran with the addition of glutamate, hydrolyzed wheat protein (HWP), yeast extract (YE) and pyridoxal-5-phosphate (PLP) was investigated. Rice bran was moistened (30% moisture content) with an electrolyzed oxidizing water and anaerobically incubated under nitrogen at 40 °C for 8 h. The incubation activated the glutamate decarboxylase (GAD) in rice bran and increased the GABA content from 10.7 to 171.5 mg/100 g. The addition of glutamate and protein hydrolysates further amplified the GABA content in the treated rice bran: 974.9, 487.4, and 372.8 mg/100 g, with 2.25% glutamate, 6% HWP, and 8% YE, respectively. Furthermore, addition of PLP (1.48 mg/100 g) as a coenzyme for GAD, together with 2.25% glutamate addition, could raise the GABA accumulation in rice bran to 2242 mg/100 g. Other amino acids in rice bran were changed in their composition by the anaerobic treatment.

Induced Resistance Against Western Flower Thrips by the Pseudomonas syringae-Derived Defense Elicitors in Tomato

Western flower thrips (WFT) Frankliniella occidentalis (Pergande) is a key agricultural pest of cultivated tomatoes. Induced host plant resistance by activating jasmonic acid (JA) signaling pathway constitutes a promising method for WFT control. The phytotoxin coronatine (COR), produced by Pseudomonas syringae pv. tomato DC3000 (Pst), mimics the plant hormone JA-Isoleucine and can promote resistance against herbivorous arthropods. Here we determined the effect of Pst and COR on tomato resistance against WFT, induction of JA and salicylic acid (SA) associated defenses, and plant chemistry. Additionally, we investigated the presence of other components in Pst-derived and filtered culture medium, and their interactive effect with COR on tomato resistance to WFT. Our results showed that infiltration of COR or Pst reduced WFT feeding damage in tomato plants. COR and Pst induced the expression of JA-associated gene and protein marker. COR also induced expression of a SA-related responsive gene, although at much less magnitude. Activation of JA defenses in COR and Pst infiltrated plants did not affect density of type VI leaf trichomes, which are defenses reported to be induced by JA. An untargeted metabolomic analysis showed that both treatments induced strong changes in infiltrated leaves, but leaf responses to COR or Pst slightly differed. Application of the Pst-derived and filtered culture medium, containing COR but not viable Pst, also increased tomato resistance against WFT confirming that the induction of tomato defenses does not require a living Pst population to be present in the plant. Infiltration of tomato plants with low concentrations of COR in diluted Pst-derived and filtered culture medium reduced WFT feeding damage in a greater magnitude than infiltration with an equivalent amount of pure COR indicating that other elicitors are present in the medium. This was confirmed by the fact that the medium from a COR-mutant of Pst also strongly reduced silver damage. In conclusion, our results indicate that induction of JA defenses by COR, Pst infection, the medium of Pst and the medium of a Pst COR^- mutant increased resistance against WFT. This was not mediated by the reinforcement of leaf trichome densities, but rather the induction of chemical defenses.