Accumulation Of Free Amino Acids Research Articles

Developmental-specific regulation promotes the free amino acids accumulation in chlorotic tea plants (Camellia sinensis)

Chlorophyll-deficient tea plant exhibits a significantly higher accumulation of free amino acids (FAAs) than normal tea plants. This study focused on the impact of leaf color and the developmental stage on FAAs in six tea germplasms while maintaining all other conditions. The total FAAs content initially increased as the leaf matured during the one-bud-two-leaves (1B2L) and one-bud-three-leaves (1B3L) stages in green germplasms, then decreased or stabilized in the one-bud-four-leaves (1B4L) stage. In contrast, chlorotic germplasms showed continuous FAAs’ content increase from 1B2L to 1B4L, thus being significantly positively correlated with total chlorophyll content. Interestingly, ethylamine content decreased with leaf maturation in both chlorotic and green germplasms, thus showing a significant negative correlation with L-theanine content only in chlorotic germplasms. Comparative RNA-seq analysis linked FAAs accumulation in chlorotic germplasm’s 1B3L to photosynthesis inhibition and in 1B4L to nitrogen assimilation promotion. Feeding experiments revealed higher L-theanine synthesis and degradation abilities in chlorotic shoots versus green shoots, with synthesis efficiency exceeding degradation efficiency. Overall, this study uncovers a developmental-specific FAAs accumulation pattern in chlorotic germplasms and offers novel insights into the precise regulation by leaf color and developmental stage.

An effective means to improve the flavor quality of traditional fermented sour meat: The salt reduction strategy

The flavor formation of fermented meat products is significantly influenced by salt. In this study, the flavor analysis methods of electronic tongue and nose, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry were utilized to explore the effect of salt content on the formation of sour meat flavor. The results demonstrated a significant decrease in pH value with the reduction of salt content (P < 0.05), while there was a significant rise in thiobarbituric acid reactive substances (TBARS) value associated with the decline in salt content (P < 0.05). Alcohols, aldehydes, and esters such as 1-octen-3-ol, 3-methyl-1-butanol, hexanal, heptanal, ethyl octanoate, ethyl heptanoate, etc. were considered to have significant contributions to the overall flavor of sour meat. The rapid accumulation of these aroma compounds under low-salt conditions was regarded as one of the key factors in the overall flavor enhancement of sour meat products. Additionally, the low-salt fermentation also promoted the accumulation of free amino acids and free fatty acids in sour meat products, thereby facilitating the formation of more complex aroma compounds. This study offers new technological ways to improve the conventional method of fermenting sour meat and offers theoretical justification for studies on salt reduction in conventionally fermented meat products.

Senescence metabolomics of &lt;i&gt;Nicotiana tabacum&lt;/i&gt; L. VBI-0 heterotrophic suspension cultures

BACKGROUND: Heterotrophic cell cultures are widely used as a model in plant biology. During a culture cycle the composition of the medium changes: the sucrose and other substrates are depleted, metabolism products are accumulated and the density increases. Finally, arrest of a growth is followed by cell death in a short time. These processes are accompanied with physiological alterations, corresponding to senescence. AIM: To resolve metabolic features of tobacco cells in growing and stationary senescent suspension cultures VBI-0. MATERIALS AND METHODS: Nicotiana tabacum VBI-0 cells were cultured in suspension MS medium supplied with 3% sucrose. Cells were sampled at 7th day, during intensive growth, and at 28th day, when the culture was in the stationary phase. The GC-MS method was used to profile the metabolites. RESULTS: Sucrose depletion in media caused starvation of heterotrophic tobacco cell culture and was associated with a decrease in the accumulation of free amino acids. At the same time, the level of pentoses and complex sugars, including sucrose, increased, while the levels of glucose and fructose were not changed significantly and levels of hexose phosphates decreased. During culture senescence cells showed higher levels of accumulation of malate, pyruvate and some other carboxylates. CONCLUSIONS: The metabolomic data indicate that culture senescence was associated with a drop in amino acids metabolism, a decrease in the activity of the upper part of glycolysis, and the accumulation of complex sugars, pentoses and carboxylates.

Biochemical components of nitrogen balance in soil under crude oil contamination and phytoremediation

Introduction. Nitrogen availability in oil contaminated soil is adversely affected due to an increase in the inorganic carbon (C) and nitrogen (N) ratio, unfavorable changes in physical, chemical and biological properties of the soil. Phytoremediation of oil contaminated soil may have a positive effect on N cycling. Changes in soil enzyme activity, content of organic and mineral N in the soil can be used as indicators of nitrogen balance. This paper aims to identify some biochemical elements of N cycling in oil contaminated soil and the effect of plants in recovering N balance in the soil. Materials and Methods. In this study artificially oil contaminated soil (50 mL of crude oil per 1 kg of soil) was remediated by plants Zea mays L. and Vicia faba var. minor. Soil samples were collected on the 10th day after oil pollution, on the 22nd day (seeds were sown), on the 65th day (30 days of plants’ growth), and on the 95th day (60 days of plants’ growth). Soil without oil and plant vegetation was used as control. We determined the nodulation ability of soil, activity of soil protease and urease, content of labile organic nitrogen and free amino acids accumulation in the soil. Results. Our study revealed the absence of nodules on V. faba roots in oil contamination conditions. Protease activity was inhibited in oil contaminated soil compared to control. Under plant vegetation and oil contamination conditions, soil protease activity increased on the 65th day, and decreased on the 95th day compared to oil contaminated soil without plants. Amino acid concentration was significantly smaller for oil contaminated soil during the experiment than for soil without oil, but amino acid content was significantly greater for soil planted with Z. mays than for soil without plants. V. faba had a stimulating effect on amino acid accumulation only for uncontaminated soil compared to soil without plants. The results have shown that the urease activity decreased in oil contaminated soil during all experimental period. Results indicated that 22 days after oil pollution, the content of labile organic N decreased in oil contaminated soil, whereas on further stages of the experiment it was not significantly different compared to control. Significant reduction of labile N was revealed for oil contaminated soil with Z. mays plants on the 95th day and with V. faba plants on the 65th day compared to uncontaminated soil with plants. Conclusions. Oil-contamination had a negative effect on all studied biochemical characteristics of soil: protease activity, urease activity, labile organic nitrogen, free amino acids accumulation. In oil contamination conditions the positive effect of Z. mays and V. faba plants was determined for protease activity on the 65th day, a positive effect of Z. mays plants on accumulation of free amino acids accumulation was observed on the 95th day. The shortage of labile N in oil contaminated soil increased during phytoremediation. Therefore application of Z. mays and V. faba plants for optimization of biochemical components of N balance in oil contaminated soil may be controversial and requires further exploration.

The Role of Tubulin and Thaumatin Genes and Osmotic Factors in Salinity Tolerance of Tomato Plants

Soil salinity is a drastic abiotic factor that affects many physiological processes and whole plants’ activities, as well as up- and down-regulating gene expression. Studying the effect of salinity on tubulin and thaumatin relative gene expression as DNA markers for salinity stress in tomato plants is a scarcely studied topic. Tubulin regulates and plays an important role in the immunolocalization of xylem and phloem fibers in stems and additionally maintains the concept of heavy microtubule contribution during cellulose microfibril confession in secondary cell walls under abiotic and biotic stresses. Like tubulin, thaumatin-like proteins are concomitant with plant defense responses against both biotic and abiotic stresses. The expression of the thaumatin gene can be meaningfully induced after plants' exposure to either drought, freezing, or salinity stresses. Thus, the present investigation was conducted to study the impact of different salinity levels (0, 75, 100, and 120 mM NaCl) on the tomato plants’ growth, osmotic adjustment, and relative gene expression of both antioxidant and salt tolerance genes. As the salt concentration intensified, the fresh and dry weight of the shoots and the roots reduced significantly, accompanied by a reduction in chlorophyll a and carotenoids. On the other hand, salinity stress significantly decreased the level of osmotica (e.g., soluble sugars and soluble proteins) in tomato tissues compared to non-saline-grown plants, while a significant accumulation of free amino acids was recorded. At the molecular level, it was observed that the relative expression of the polyphenol oxidase, peroxidase, and thaumatin genes was high at the level of 100 mM NaCl, but it was suppressed at 120 mM NaCl. In contrast, salinity down-regulated tubulin gene expression in stressed tomato plants relative to controls, revealing various mechanisms that instigated salinity tolerance, which is concentration-dependent. The study recommended the importance of amino acids as osmotica as well as the relative expressions of PPO, peroxidase, and thaumatin genes in conferring salt tolerance at low to moderate salt levels.

Integrated “-omics” analysis highlights the role of brassinosteroid signaling and antioxidant machinery underlying improved rice seed longevity during artificial aging treatment

Seed longevity is a critical characteristic in agriculture, yet the specific genes/proteins responsible for this trait and the molecular mechanisms underlying reduced longevity during seed aging remain largely elusive. Here we report the comparative proteome and metabolome profiling of three rice cultivars exhibiting varying degrees of aging tolerance: Dharial, an aging-tolerant cultivar; Ilmi, an aging-sensitive cultivar; and A2, a moderately aging-tolerant cultivar developed from the crossbreeding of Dharial and Ilmi. Artificial aging treatment (AAT) markedly reduced the germination percentage and enhanced the activities of antioxidant enzymes in all the cultivars. Further, proteomics results showed a key role of the ubiquitin (Ub)-proteasome pathway in the degradation of damaged proteins during AAT while other proteases were majorly reduced. In addition, proteins associated with energy production and protein synthesis were strongly reduced in Ilmi while these were majorly increased in A2 and Dharial. These, along with metabolomics results, suggest that Ub-proteasome mediated protein degradation during AAT results in the accumulation of free amino acids in Ilmi while tolerant cultivars potentially utilize those for energy production and synthesis of stress-related proteins, especially hsp20/alpha-crystallin family protein. Additionally, both Dharial and A2 seem to activate brassinosteroid signaling and suppress jasmonate signaling which initiates a signaling cascade that allows accumulation of enzymatic and non-enzymatic antioxidants for efficient detoxification of aging-induced ROS. Taken together, these results provide an in-depth understanding of the aging-induced changes in rice seeds and highlight key pathways responsible for maintaining seed longevity during AAT.

The content of amino acids in tomato plants when using the preparations “Monosodium Glutamate” and “Aminozol” in conditions of salt stress

Relevance. The study of the effect of preparations containing amino acids on the accumulation of free amino acids in plants is relevant in assessing their regulatory and anti-stress effects.Methods. A laboratory experiment was carried out in 2020 on tomato plants of the Betta variety. Gray forest medium loamy soil was used as a substrate. The experiment was performed on soil with different salinity — a) control (the soil is not saline), b) saline soil (50 mmol/kg NaCl), c) saline soil (100 mmol/kg NaCl), using three feeding options: without top dressing, top dressing with “Sodium Glutamate”, top dressing with “Aminozol”. Amino acids were extracted from the roots and aboveground parts of plants in the vegetative growth phase with a mixture of “ethanol + chloroform + water” (12:5:2) and the method of high-performance liquid chromatography (HPLC) with pre-columnar derivatization of amino acids with phenylisothiocyanate was used. Results. Soil salinization with sodium chloride caused an increase in the amount of free amino acids in tomato seedlings. The total amino acid content increased to 849.8 µg/kg (50 mmol/kg NaCl) and 606.9 µg/kg (100 mmol/kg NaCl) compared to the control soil (385.3 µg/kg). Salinity contributed to the accumulation of serine (from 50.4 to 414.4 µg/kg) in seedlings. Treatment with preparations (“Monosodium glutamate” and “Aminozol”) affected the accumulation of a number of amino acids responsible for plant stress resistance. Supplementation with monosodium glutamate increased the total amino acid concentration to 1146.6 µg/kg (50 mmol/kg NaCl) and 1017.7 µg/kg (100 mmol/kg NaCl) compared to the corresponding variants without supplementation. At the same time, the content of glutamic (up to 188.3 and 425.1 µg/kg) and aspartic (up to 50.8 and 198.7 µg/kg) acids increased. “Aminosol” contributed to an increase in the amount of amino acids to 1834.2 µg/kg (50 mmol/kg NaCl) and 934.4 µg/kg (100 mmol/kg NaCl), respectively.

Comprehensive dissection of variation and accumulation of free amino acids in tea accessions.

Free amino acids (FAAs) positively determine the tea quality, notably theanine (Thea), endowing umami taste of tea infusion, which is the profoundly prevalent research in albino tea genetic resources. Therefore, 339 tea accessions were collected to study FAAs level for deciphering its variation and accumulation mechanism. Interestingly, alanine (Ala) and Thea which had the highest diversity index (H') value among three varieties of Camellia sinensis (L.) O. Kuntze were significantly higher than wild relatives (P < 0.05). The intraspecific arginine (Arg) and glutamine (Gln) contents in C. sinensis var. assamica were significantly lower than sinensis and pubilimba varieties. Moreover, the importance of interdependencies operating across FAAs and chlorophyll levels were highlighted via the cell ultrastructure, metabolomics, and transcriptome analysis. We then determined that the association between phytochrome interacting factor 1 (CsPIF1) identified by weighted gene co-expression network analysis (WGCNA) and Thea content. Intriguingly, transient knock-down CsPIF1 expression increased Thea content in tea plant, and the function verification of CsPIF1 in Arabidopsis also indicated that CsPIF1 acts as a negative regulator of Thea content by mainly effecting the genes expression related to Thea biosynthesis, transport, and hydrolysis, especially glutamate synthase (CsGOGAT), which was validated to be associated with Thea content with a nonsynonymous SNP by Kompetitive Allele-Specific PCR (KASP). We also investigated the interspecific and geographical distribution of this SNP. Taken together, these results help us to understand and clarify the variation and profile of major FAAs in tea germplasms and promote efficient utilization in tea genetic improvement and breeding.

Ethylene enhances transcriptions of asparagine biosynthetic genes in soybean (Glycine max L. Merr) leaves

ABSTRACT Soybean, a vital protein-rich crop, offers bioactivity that can mitigate various chronic human diseases. Nonetheless, soybean breeding poses a challenge due to the negative correlation between enhanced protein levels and overall productivity. Our previous studies demonstrated that applying gaseous phytohormone, ethylene, to soybean leaves significantly boosts the accumulation of free amino acids, particularly asparagine (Asn). Current studies also revealed that ethylene application to soybeans significantly enhanced both essential and non-essential amino acid contents in leaves and stems. Asn plays a crucial role in ammonia detoxification and reducing fatigue. However, the molecular evidence supporting this phenomenon remains elusive. This study explores the molecular mechanisms behind enhanced Asn accumulation in ethylene-treated soybean leaves. Transcriptional analysis revealed that ethylene treatments to soybean leaves enhance the transcriptional levels of key genes involved in Asn biosynthesis, such as aspartate aminotransferase (AspAT) and Asn synthetase (ASN), which aligns with our previous observations of elevated Asn levels. These findings shed light on the role of ethylene in upregulating Asn biosynthetic genes, subsequently enhancing Asn concentrations. This molecular insight into amino acid metabolism regulation provides valuable knowledge for the metabolic farming of crops, especially in elevating nutraceutical ingredients with non-genetic modification (GM) approach for improved protein content.

Role of salicylic acid in improving the yield of two mung bean genotypes under waterlogging stress through the modulation of antioxidant defense and osmoprotectant levels

Waterlogging (WL) is a major hindrance to the growth and development of leguminous crops, including mung bean. Here, we explored the effect of salicylic acid (SA) pretreatment on growth and yield output of two elite mung bean genotypes (BU Mung bean-4 and BU Mung bean-6) subjected to WL stress. SA pretreatment significantly improved shoot dry weight, individual leaf area, and photosynthetic pigment contents in both genotypes, while those improvements were higher in BU Mung bean-6 when compared with BU Mung bean-4. We also found that SA pretreatment significantly reduced the reactive oxygen species-induced oxidative burden in both BU Mung bean-6 and BU Mung bean-4 by enhancing peroxidase, glutathione S-transferase, catalase, and ascorbate peroxidase activities, as well as total flavonoid contents. SA pretreatment further improved the accumulation of proline and free amino acids in both genotypes, indicating that SA employed these osmoprotectants to enhance osmotic balance. These results were particularly corroborated with the elevated levels of leaf water status and leaf succulence in BU Mung bean-6. SA-mediated improvement in physiological and biochemical mechanisms led to a greater yield-associated feature in BU Mung bean-6 under WL conditions. Collectively, these findings shed light on the positive roles of SA in alleviating WL stress, contributing to yield improvement in mung bean crop.

An integrated physiological and metabolic approach reveals how Restinga shrub species cope with the iron ore tailing plume along the coastal region of Espírito Santo-Brazil

The iron ore tailings resulting from the rupture of the Fundão dam, in Mariana-MG, Brazil, impacted the Doce River basin affecting the flora and fauna in the region. Plants that grow in contaminated soil exhibited changes in metabolism, and reduced growth and biomass, coupled with phytotoxicity symptoms. However, several species are able to exclude or even accumulate metals through adaptive strategies. Here, we investigated physiological and metabolic responses in Restinga shrub species affected by the mining plume from the contaminated sea. We carried out all analyses in two different shrub species at eight sample Restinga stations along the coastal region of Espírito Santo state, Brazil. Accumulation of metals during the rainy season coupled with higher levels of these metals in sampling stations were observed. Increased stomatal conductance coupled with higher intercellular CO2 concentration were observed during the rainy season which was characterized by high temperatures. Correlations between metals and metabolic responses were evident and our results pointed out the occurrence of acclimation responses such as maintenance of photosynthesis, and accumulation of free amino acids, carbohydrates, and antioxidants. The differential physiological responses found between the two species analyzed here suggest a genetic load capable of responding, at least partially, to stressful conditions associated with the iron ore tailing plume.

Autophagy contributes to increase the content of intracellular free amino acids in hard clam (Mercenaria mercenaria) during prolonged exposure to hypersaline environments

Marine bivalves in intertidal zones and land-based seawater ponds are constantly subjected to a wide range of salinity fluctuations due to heavy rainfall, intense drought, and human activities. As osmoconformers, bivalves rely primarily on rapid release or accumulation of free amino acids (FAAs) for osmoregulation. Euryhaline bivalves are capable of withstanding hyposaline and hypersaline environments through regulation of physiology, metabolism, and gene expression. However, current understanding of the molecular mechanisms underlying osmoregulation and salinity adaptation in euryhaline bivalves remains largely limited. In this study, RNA-seq, WGCNA and flow cytometric analysis were performed to investigate the physiological responses of hard clams (Mercenaria mercenaria) to acute short-term hyposalinity (AL) and hypersalinity (AH), and chronic long-term hyposalinity (CL) and hypersalinity (CH) stress. We found that amino acids biosynthesis was significantly inhibited and aminoacyl-tRNA biosynthesis was augmented to decrease intracellular osmolarity during hyposaline exposure. Under CH, numerous autophagy-related genes (ATGs) were highly expressed, and the autophagy activity of gill cells were significantly up-regulated. A significant decrease in total FAAs content was observed in gills after NH4Cl treatment, indicating that autophagy was crucial for osmoregulation in hard clams during prolonged exposure to hypersaline environments. To prevent premature or unnecessary apoptosis, the expression of cathepsin L was inhibited under AL and AH, and inhibitors of apoptosis was augmented under CL and CH. Additionally, neuroendocrine regulation was involved in salinity adaption in hard clams. This study provides novel insights into the physiological responses of euryhaline marine bivalves to hyposaline and hypersaline environments.

Insights into effects of salt stress on the oil-degradation capacity, cell response, and key metabolic pathways of Bacillus sp. YM1 isolated from oily food waste compost

A novel bacterial strain, Bacillus sp. YM1, was isolated from compost for the efficient degradation of oily food waste under salt stress. The strain's lipase activity, oil degradation ability, and tolerance to salt stress were evaluated in a liquid medium. Additionally, the molecular mechanisms (including key genes and functional processes) underlying the strain's salt-resistant degradation of oil were investigated based on RNA-Seq technology. The results showed that after 24 h of microbial degradation, the degradation rate of triglycerides in soybean oil was 80.23% by Bacillus sp. YM1 at a 30 g L−1 NaCl concentration. The metabolizing mechanism of long-chain triglycerides (C50–C58) by the YM1 strain, especially the biodegradation rate of triglycerides (C18:3/C18:3/C18:3), could reach 98.65%. The most substantial activity of lipase was up to 325.77 U·L−1 at a salinity of 30 g L−1 NaCl. During salt-induced stress, triacylglycerol lipase was identified as the crucial enzyme involved in oil degradation in Bacillus sp. YM1, and its synthesis was regulated by the lip gene (M5E02_13495). Bacillus sp. YM1 underwent adaptation to salt stress through various mechanisms, including the accumulation of free amino acids, betaine synthesis, regulation of intracellular Na+/K+ balance, the antioxidative response, spore formation, and germination. The key genes involved in Bacillus sp. YM1's adaptation to salt stress were responsible for the synthesis of glutamate 5-kinase, superoxide dismutase, catalase, Na+/H+ antiporter, general stress protein, and sporogenic proteins belonging to the YjcZ family. Results indicated that the isolated strain of Bacillus sp. YM1 could significantly degrade oil in a short time under salt stress. This study would introduce new salt-tolerant strains for coping with the biodegradation of oily food waste and provide gene targets for use in genetic engineering.

OsCM regulates rice defence system in response to UV light supplemented with drought stress.

Studies on plant responses to combined abiotic stresses are very limited, especially in major crop plants. The current study evaluated the response of chorismate mutase overexpressor (OxCM) rice line to combined UV light and drought stress. The experiments were conducted in pots in a growth chamber, and data were assessed for gene expression, antioxidant and hormone regulation, flavonoid accumulation, phenotypic variation, and amino acid accumulation. Wild-type (WT) rice had reduced the growth and vigour, while transgenic rice maintained growth and vigour under combined UV light and drought stress. ROS and lipid peroxidation analysis revealed that chorismate mutase (OsCM) reduced oxidative stress mediated by ROS scavenging and reduced lipid peroxidation. The combined stresses reduced biosynthesis of total flavonoids, kaempferol and quercetin in WT plants, but increased significantly in plants with OxCM. Phytohormone analysis showed that SA was reduced by 50% in WT and 73% in transgenic plants, while ABA was reduced by 22% in WT plants but increased to 129% in transgenic plants. Expression of chorismate mutase regulates phenylalanine biosynthesis, UV light and drought stress-responsive genes, e.g., phenylalanine ammonia lyase (OsPAL), dehydrin (OsDHN), dehydration-responsive element-binding (OsDREB), ras-related protein 7 (OsRab7), ultraviolet-B resistance 8 (OsUVR8), WRKY transcription factor 89 (OsWRKY89) and tryptophan synthase alpha chain (OsTSA). Moreover, OsCM also increases accumulation of free amino acids (aspartic acid, glutamic acid, leucine, tyrosine, phenylalanine and proline) and sodium (Na), potassium (K), and calcium (Ca) ions in response to the combined stresses. Together, these results suggest that chorismate mutase expression induces physiological, biochemical and molecular changes that enhance rice tolerance to combined UV light and drought stresses.

The Effects of Acute Exposure to Ammonia on Oxidative Stress, Hematological Parameters, Flesh Quality, and Gill Morphological Changes of the Large Yellow Croaker (Larimichthys crocea).

Ammonia is considered to be the major chemical pollutant causing fish poisoning in aquaculture. This research aimed to evaluate the impact of acute ammonia exposure on the large yellow croaker's meat quality, gill morphology, liver oxidative stress, and hematological parameters. The fish were exposed to total ammonia nitrogen concentrations of 0, 2.96, 5.92, and 8.87 mg/L for 48 h, respectively. The findings demonstrated that all ammonia-exposed fish had higher liver lactate dehydrogenase and glutamic oxalate transaminase activities. The glucose, blood urea nitrogen, and creatinine levels in 8.87 mg/L total ammonia nitrogen (TAN) were higher than other samples. The total protein, albumin, and triglyceride levels in serum decreased significantly in ammonia-exposed samples. After 48 h of ammonia exposure, superoxide dismutase activities showed a 76.1%, 118.0%, and 156.8% increase when fish were exposed to 2.96, 5.92, and 8.87 mg/L TAN, respectively. Catalase activities and glutathione contents were considerably higher (p < 0.05) in all ammonia-treated samples compared to 0 mg/L TAN. The ammonia-treated gill lamellae become thicker, shorter, and curved. Additionally, the ammonia exposure resulted in the accumulation of free amino acids and the loss of nucleotides. The inosine monophosphate and adenosine monophosphate contents in the flesh were decreased after 12 h of exposure to 2.96, 5.92, and 8.87 mg/L ammonia compared to the control group. Overall, large yellow croakers exposed to ammonia for 6 h presented not only changes in serum composition but also oxidative stress, liver and gill tissue damage and flesh quality deterioration.

Aminopeptidase Play a Critical Role in the Accumulation of Free Amino Acids in Abalone (Haliotis discus hannai) During Cold Storage

Aminopeptidase Play a Critical Role in the Accumulation of Free Amino Acids in Abalone (Haliotis discus hannai) During Cold Storage

Silicon Induces Heat and Salinity Tolerance in Wheat by Increasing Antioxidant Activities, Photosynthetic Activity, Nutrient Homeostasis, and Osmo-Protectant Synthesis.

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

Health Risk and Quality Assessment of Vegetables Cultivated on Soils from a Heavily Polluted Old Mining Area.

Three garden vegetables-radish, carrot and lettuce-were cultivated in a pot experiment using two soils from the Příbram area polluted mainly by cadmium (Cd), zinc (Zn), lead (Pb) and chromium (Cr). The soils of the Příbram district, Czech Republic, are heavily polluted as a result of the atmospheric deposition of toxic elements originating from historic lead-silver mining and smelting activities. The results showed that lettuce absorbed the highest amounts of toxic elements (Cd 28 and 30, Cr 12 and 13, Zn 92 and 205 mg·kg-1 DW), except Pb, which was higher in radish (30 and 49 mg·kg-1 DW). Changes in macronutrient contents in edible parts were not found, except for sulfur. A higher total free amino acids (fAAs) accumulation was shown in all vegetables in more contaminated soil, with the highest fAA content being in radish. A group of essential fAAs reached 7-24% of total fAAs in vegetables. The risk to human health was characterized using the target hazard quotient and total hazard index (HI). The cumulative effect of the consumption of vegetables with HI > 1 showed possible non-carcinogenic health effects for lettuce and carrot. HI decreased in the order Cd > Pb > Cr > Zn. The carcinogenic risk of toxic elements decreased in the order Cd > Cr > Pb (0.00054, 0.00026, 0.00003). These values showed a carcinogenic risk from the consumption of lettuce and carrot and confirmed that the adult population of the studied area is at high risk if lettuce and carrot cultivated in this area are consumed daily.

Silicon alleviates drought damage by increasing antioxidant and photosynthetic performance in cowpea

AbstractWater deficits have been considered the most restrictive environmental constraint on agricultural production worldwide. The current study aimed to investigate the role of silicon nutrition (Si) in activating defence mechanisms against drought damage in cowpea cultivars. The experiments were carried out in a randomized block design in a 2 × 2 × 4 factorial scheme, corresponding to two cowpea cultivars (BRS Novaera and BRS Tumucumaque), two water regimes (control well‐irrigated and water deficit) and four Si levels (0, 1.0, 2.0 and 4.0 mM). Plant growth and physiological and biochemical indicators were evaluated 28 days after drought imposition. Drought significantly reduced the photosynthetic pigments (Chl b and Chl total), gas exchanges (net photosynthesis, transpiration and stomatal conductance) and, consequently, all growth parameters of cowpea plants compared with well‐irrigated plants. However, Si at 2.0 mM activated critical responses in the BRS Novaera cultivar under drought, almost recovering plant performance and increasing drought tolerance. The beneficial Si‐induced effects were closely related to increased accumulation of Si, carbohydrates and free amino acids that likely promoted osmoregulation and were associated with an improved antioxidant system composed of proline and the activity of SOD, CAT and APX. These metabolic alterations were sufficient to enable enhanced net photosynthesis and plant growth. In conclusion, Si counteracts the deleterious effects of water deficit by efficiently inducing antioxidant defence and photosynthetic performance in Novaera plants. Si nutrition may constitute a potential strategy to cultivate cowpea plants in water‐scarce areas from arid and semiarid regions.

Effect of weak magnetic field on the water-holding properties, texture, and volatile compounds of pork and beef during frozen storage

The weak magnetic field has recently attracted much attention for improving the quality of frozen food due to its mild effectiveness and near-complete transmission through the food matrix. This study aimed to explore the effect of the magnetic field with 1 mT and 50 Hz on the freezing process and storage quality of pork and beef. The results showed that the freezing point of beef stored under the magnetic field was −1.7 °C, which was 0.5 °C lower than that of conventional frozen (CF) groups, and the phase transition times of pork and beef were reduced by 55.56% and 50.00%, respectively. The magnetic field maintained higher water-holding capacity and decreased drip loss and cooking loss for both types of meat. Coherently, the evaporation and redistribution of water was inhibited by MF, as indicated by the magnetic resonance imaging results. The magnetic field also effectively moderated the hardening in texture, odor deterioration and color change of frozen pork and beef. Less accumulation of free amino acids suggested the degradation of protein was suppressed under magnetic field . The present study would provide a scientific reference for the application of weak magnetic field in meat preservation.