Free Amino Sugars Research Articles

Capturing and Explaining Sensory Differences among Organically Grown Vegetable-Soybean Varieties Grown in Northern California.

Vegetable soybean (VS), known as edamame, is appreciated for its robust flavor and exceptional nutrient content. Although the United States is one of the world's leading producers of soy, only a fraction is harvested as edamame. Research involving varietal differences is very limited, particularly among U.S. consumers. Sensory attributes of three VS varieties grown in Northern California (with organic methods) were assessed: Giant Midori (GM), ButterBean (BB), and Kuroshinja (KU). Participants (n = 74) rated four characteristics: flavor, texture, appearance, and overall liking on unlabeled, 11-point hedonic scales and were asked if they would purchase the variety. A small portion of these participants would again evaluate the varieties, using free choice profiling (FCP) methodology. After these evaluations, texture analyzer, colorimeter, and high-performance liquid chromatography (free amino acids, sugars, and isoflavones) testing were performed. Among tested varieties, distinct differences in quality were found, withGM preferred first, followed by KU, and BB. GM was significantly harder, a more intense green, had more free sugars and isoflavones and fewer free amino acids, whereas KU and BB trended to be the opposite. Analyzing FCP data with a General Procrustes Analysis, varieties were separated in different factors for flavor and texture, but not appearance. Although repeated, and larger trials are needed, our study signifies that consumers are able to detect differences among VS varieties. Further research may influence producers to grow the variety likely to be most profitable and marketable.

Identification of lactic acid bacteria and yeasts, and characterization of food components of sourdoughs used in Japanese bakeries

Sourdough is a low-pH, fermented product prepared using lactic acid bacteria and yeast mixed with rye flour, wheat flour, and water. It is used and backslopped in bakeries because it enhances texture, flavor, and dough expansion of bread. Various lactic acid bacteria and yeasts have been identified in sourdough, especially in the West. However, microbial and physical characteristics of sourdough from Japan have not been investigated. Here, we characterized the microbial composition and food component characteristics of sourdough from four bakeries in Kansai region, Japan, and performed sensory and quality evaluation of baguettes enriched with 10% sourdough. We detected different species of lactic acid bacteria such as Lactobacillus brevis, Lactobacillus alimentarius, Lactobacillus pentosus, Lactobacillus vaccinostercus, Lactobacillus sanfranciscensis, and Lactobacillus sakei. The identified yeasts primarily included Saccharomyces cerevisiae, with Candida humilis detected in some samples. Components such as amino acids, lactic acid, acetic acid, ethanol, 3-methyl-1-butanol, ethyl acetate, and phenethyl alcohol differed among samples and distinctively affected flavor, quality, and aroma of sourdough-enriched baguettes. The different species of lactic acid bacteria and the ratio of lactic acid bacteria to yeasts possibly affected food components such as free amino acids, sugars, and organic acids via the Maillard reaction, which influences the savory aromas of bread. Future investigation of the effect of lactic acid bacteria will help to improve the overall quality of bread.

Drying and extraction effects on three edible brown seaweeds for metabolomics

Metabolomics is often used to comprehensively elucidate the metabolites in organisms like seaweed. Amino acids hydrolysed from proteins and certain targeted metabolites in seaweed have been investigated. However, water-soluble metabolites like free amino acids, organic acids, and sugars have seldom been comprehensively analysed. Metabolomics are valuable tools for these studies, but they require optimisation of pre-treatment methodology. Here, we evaluated various pre-treatment drying and extraction methods for brown seaweed metabolomics. Three edible brown seaweeds (Cladosiphon okamuranus [Mozuku], Saccharina japonica [Kombu], and Undaria pinnatifida [Wakame]) were used. Freeze-drying and oven-drying at both 40 and 80 °C were investigated. Methanol-water extracts with and without chloroform were compared. Metabolites were evaluated and quantified using liquid chromatography-mass spectrometry and capillary electrophoresis-mass spectrometry. The results showed that metabolite profiling was determined mainly by seaweed species identity rather than pre-treatment method. Freeze-drying yielded higher metabolite concentrations than oven-drying at either 40 or 80 °C. The effects of extraction with and without chloroform on metabolite concentration varied with seaweed species.

Significant release and microbial utilization of amino sugars and d-amino acid enantiomers from microbial cell wall decomposition in soils

Amino sugars and d-amino acid enantiomers are major components of bacterial and fungal cell walls (i.e. peptidoglycan and chitin) and are often used as biomarkers of microbial residue turnover in soils. However, little is known about the in situ decomposition rates of microbial cell wall residues and how soil physicochemical properties affect this process. In this study, we investigated the in situ gross production and consumption rates of free amino sugars (glucosamine and muramic acid) and amino acids (meso-diaminopimelic acid, l-alanine, and d-alanine) by a novel isotope pool dilution assay using 15N-labeled amino compounds. Soils were obtained from six sites differing in land management (cropland, pasture, and forest) and bedrock (silicate and limestone) and incubated at three temperatures (5, 15, and 25 °C). Free glucosamine released during the decomposition of peptidoglycan and chitin contributed significantly to the extractable soil organic nitrogen pool. Gross production and consumption rates of glucosamine were higher than those of individual amino acids, i.e. L- and d-alanine. Muramic acid had a longer mean residence time (68 h compared to 2.7 h for glucosamine, L- and d-alanine) and made a negligible contribution to soil organic nitrogen fluxes, indicating that free muramic acid was not a major decomposition product of peptidoglycan in soils. Meso-diaminopimelic acid and d-alanine exhibited comparable gross production and consumption rates with l-alanine. These amino acids can be used as indicators to estimate the decomposition of peptidoglycan from bacterial cell wall residues. We found that chitin decomposition was greater in silicate soils, while peptidoglycan decomposition dominated in limestone soils. Glucosamine production rates were not correlated with soil total amino sugars, microbial community structure, or hydrolytic enzyme activities, but were highest in soils with low pH and high sand content, indicating that soil texture and soil pH may strongly influence the decomposition of amino sugar polymers. In contrast, mDAP, L- and d-alanine gross production and consumption rates were positively correlated with soil pH and clay content, due to greater depolymerization of peptidoglycan stem peptides in limestone soils. This isotope pool dilution approach strongly improves our understanding of the mechanisms and environmental controls on microbial cell wall decomposition in soils.

Effects of humic substances and indole-3-acetic acid on Arabidopsis sugar and amino acid metabolic profile

Humic substances (HS) are known to influence plant physiological processes, enhancing crop yield, plant growth and nutrient uptake. The present study sought to gain a better understanding of the specific effects of HS application on the abundance of metabolites in plant tissues, using mass spectrometry analyses. Arabidopsis thaliana plants, grown in hydroponic conditions, were treated for 8 h with indole-3-acetic acid (IAA), HS from International Humic Substances Society (IHSS) and HS from earthworm faeces (EF), respectively. Humic substances structural characteristics were analyzed by 1H NMR an FT-IR spectroscopies. Root and leaf free amino acids, sugar alcohols and carbohydrate contents, and leaf amino acids from protein hydrolysis were identified and quantified by gas chromatography-mass spectrometry (GC/MS), and liquid chromatography-mass spectrometry (LC/MS). Canonical discriminant analysis (CDA) was used to evaluate the influence of the treatments on the studied parameters. EF treatment had the highest influence on metabolite profiles compared to the control, IAA and IHSS. CDA analysis highlighted a clear distinction between EF and IHSS plant physiological responses, depending on the different chemical and structural properties of the HS. IAA-treated plants showed no significant difference from the control. A better understanding of the specific effects of different HS, also related to their chemical characteristics, might serve as a basis for the identification of marker compounds for HS bioactivity.

Effects of different types of soy sauce on the formation of heterocyclic amines in roasted chicken

ABSTRACTThe objective of the study was to determine the effect of different types of soy sauce and marinating time on the formation of heterocyclic amines (HCAs) in roasted chicken. Chicken breast samples were marinated with sweet, salty, light and dark soy sauce at 0, 3, 6 and 12 h (control treatment was the chicken without marinade). The concentrations of free amino acids, sugars and creatinine were determined before roasting while HCA concentrations were determined after roasting. All types of soy sauce significantly increased (p ≤ 0.05) the concentration of HCAs in roasted chicken with increasing marinating time. The highest increment of total concentration of HCAs was found in samples marinated with light soy sauce (887%) followed by dark (375%), salty (193%) and sweet (169%) at 12 h. PhIP (2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine) showed a substantial reduction in samples only momentarily marinated with sweet, salty and dark soy sauce (0 h). Free amino acids were found to be more strongly correlated with the formation of HCAs than reducing sugars or creatinine.

Effects of wheat gluten hydrolysates fractionated by different methods on the growth and fermentation performances of brewer's yeast under high gravity fermentation

Summary Wheat gluten hydrolysates (WGH) were fractionated through ultrafiltration membrane with molecular weight (Mw) cut-off of 3 kDa and ethanol precipitation, respectively. WGH and their fractions were used to examine their effects on the growth and fermentation performances of brewer's yeast under high gravity fermentation. Results showed that WGH and their fractions exhibited significant differences in biomass accumulation, viability, ethanol yield, free amino nitrogen and sugar consumptions under high gravity fermentation. Compared to WGH, the fractions with Mw < 3 kDa and the supernatant of WGH treated with ethanol precipitation showed better fermentation performance for brewer's yeast. The relatively lower molecular weight and the higher levels of Leu, Lys, His and Arg in these two fractions might be responsible for their bioactivity for brewer's yeast. Thus, both ultrafiltration and ethanol precipitation could be used as efficient methods for enriching peptides with significant growth- and fermentation-promoting activity for brewer's yeast under high gravity fermentation.

Flux Analysis of Free Amino Sugars and Amino Acids in Soils by Isotope Tracing with a Novel Liquid Chromatography/High Resolution Mass Spectrometry Platform

Soil fluxomics analysis can provide pivotal information for understanding soil biochemical pathways and their regulation, but direct measurement methods are rare. Here, we describe an approach to measure soil extracellular metabolite (amino sugar and amino acid) concentrations and fluxes based on a 15N isotope pool dilution technique via liquid chromatography and high-resolution mass spectrometry. We produced commercially unavailable 15N and 13C labeled amino sugars and amino acids by hydrolyzing peptidoglycan isolated from isotopically labeled bacterial biomass and used them as tracers (15N) and internal standards (13C). High-resolution (Orbitrap Exactive) MS with a resolution of 50 000 allowed us to separate different stable isotope labeled analogues across a large range of metabolites. The utilization of 13C internal standards greatly improved the accuracy and reliability of absolute quantification. We successfully applied this method to two types of soils and quantified the extracellular gross fluxes of 2 amino sugars, 18 amino acids, and 4 amino acid enantiomers. Compared to the influx and efflux rates of most amino acids, similar ones were found for glucosamine, indicating that this amino sugar is released through peptidoglycan and chitin decomposition and serves as an important nitrogen source for soil microorganisms. d-Alanine and d-glutamic acid derived from peptidoglycan decomposition exhibited similar turnover rates as their l-enantiomers. This novel approach offers new strategies to advance our understanding of the production and transformation pathways of soil organic N metabolites, including the unknown contributions of peptidoglycan and chitin decomposition to soil organic N cycling.

Status of Defensive Enzymes and Contents of Total Phenols, Tannins and Nutrients Determine Aphid Resistance in Barley

The present investigation was carried out to identify the biochemical traits responsible for aphid resistance in barley (Hordeum vulgare L). The genotypes showing differential response towards aphid attack, i.e. EC-492253, EC-492255, EC-492350, BCU-423 and PL-426 were taken for the present study. The grain yield was found to be maximum in EC-492253 and BCU-423, moderate in EC-492255 and EC-492350 while minimum in PL-426 genotype under natural aphid attack. The activities of defensive enzymes viz. polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), β-1, 3-glucanase and chitinase were determined in the flag leaves and grains of all the genotypes during different stages of development. The various biochemical constituents, i.e. total phenols, total soluble proteins, free amino acids, sugars and tannins were also estimated. The higher activities of PAL, PPO, β-1, 3-glucanase and chitinase along with the higher contents of total phenols and tannins in the flag leaves and grains of tolerant genotypes might attribute towards pest resistance. On the other hand, the higher contents of total soluble proteins, free amino acids and sugars in the flag leaves of susceptible genotype could be responsible for making it a better host for the aphids. The results of the multivariate principal component analysis showed that the susceptible, moderately tolerant and highly tolerant genotypes occupied distinct positions on the graph on the basis of enzymatic activities and biochemical constituents. It was further observed that there was a fine relation between the biochemical traits identified for stress tolerance and the grain yield of these genotypes.

A genetic analysis of meat compositions in Japanese Black cattle: Genetic parameters and sex influence.

Meat composition in beef is related to eating quality and food functionality. Genetic parameters for several meat compositions including free amino acid, peptide and sugar, however, remain poorly described. In this study, we estimated genetic parameters for 51 meat components, including free amino acids, peptides, sugars and fatty acid compositions, and two carcase traits in 1,354 heifers and 1,797 steers of Japanese Black cattle. Heritability estimates were generally equivalent to or moderately greater than those in previous studies of this breed. Genetic correlations between free amino acids, peptides and sugars and carcase traits were often negative, suggesting a trade-off between traits. Using two-trait animal models that treat records from the two sexes as different traits, we estimated sex-specific heritabilities and cross-sex genetic correlations which indicate the sex differences in genetic architecture. In these analyses, 12 traits showed significant heritability differences between sexes and cross-sex genetic correlations occasionally deviated from unity. These results could be used to inform future breeding schemes and investigations of the genetic architecture of meat compositions in beef.

Overexpression of a Plasma Membrane-Localized SbSRP-Like Protein Enhances Salinity and Osmotic Stress Tolerance in Transgenic Tobacco.

An obligate halophyte, Salicornia brachiata grows in salt marshes and is considered to be a potential resource of salt- and drought-responsive genes. It is important to develop an understanding of the mechanisms behind enhanced salt tolerance. To increase this understanding, a novel SbSRP gene was cloned, characterized, over-expressed, and functionally validated in the model plant Nicotiana tabacum. The genome of the halophyte S. brachiata contains two homologs of an intronless SbSRP gene of 1,262 bp in length that encodes for a stress-related protein. An in vivo localization study confirmed that SbSRP is localized on the plasma membrane. Transgenic tobacco plants (T1) that constitutively over-express the SbSRP gene showed improved salinity and osmotic stress tolerance. In comparison to Wild Type (WT) and Vector Control (VC) plants, transgenic lines showed elevated relative water and chlorophyll content, lower malondialdehyde content, lower electrolyte leakage and higher accumulation of proline, free amino acids, sugars, polyphenols, and starch under abiotic stress treatments. Furthermore, a lower build-up of H2O2 content and superoxide-radicals was found in transgenic lines compared to WT and VC plants under stress conditions. Transcript expression of Nt-APX (ascorbate peroxidase), Nt-CAT (catalase), Nt-SOD (superoxide dismutase), Nt-DREB (dehydration responsive element binding factor), and Nt-AP2 (apetala2) genes was higher in transgenic lines under stress compared to WT and VC plants. The results suggested that overexpression of membrane-localized SbSRP mitigates salt and osmotic stress in the transgenic tobacco plant. It was hypothesized that SbSRP can be a transporter protein to transmit the environmental stimuli downward through the plasma membrane. However, a detailed study is required to ascertain its exact role in the abiotic stress tolerance mechanism. Overall, SbSRP is a potential candidate to be used for engineering salt and osmotic tolerance in crops.

Estimates of genetic parameters for chemical traits of meat quality in Japanese black cattle.

Genetic parameters for 54 carcass and chemical traits, such as general composition (moisture, crude fat and crude protein), fatty acid composition and water‐soluble compounds (free amino acids, peptides, nucleotides and sugars) of 587 commercial Japanese Black cattle were assessed. Heritability estimates for carcass traits and general composition ranged between 0.19–0.28, whereas those for fatty acid composition ranged between 0.11–0.85. Most heritability estimates for water‐soluble compounds were lower than 0.30; these traits were affected by aging period. Moderate heritability was observed for glutamine, alanine, taurine, anserine, inosine 5′‐monophosphate (IMP), inosine and myo‐inositol. In particular, heritability estimates were the highest (0.66) for taurine. Traits with moderate heritability were unaffected by aging period, with the exception of IMP, which was affected by aging period but exhibited moderate heritability (0.47). Although phenotypic correlations of water‐soluble compounds with carcass weight (CW), beef marbling standard (BMS) and monounsaturated fatty acid were generally low, genetic correlations between these traits were low to high. At the genetic level, most of the water‐soluble compounds were positively correlated with monounsaturated fatty acid but negatively correlated with CW and BMS. Thus, our results indicate that genetic variance and correlations could exist and be captured for some of the water‐soluble compounds.

Root exudation index: screening organic acid exudation and phosphorus acquisition efficiency in soybean genotypes

High-molecular-weight secretory proteins and low-molecular-weight exudates (carboxylates, phenols, free amino acids and sugars) released from roots of soybean (Glycine max (L.) Merr.) differentially influence genotypic phosphorus (P) acquisition efficiency (PAE). We hypothesised that genotypes with higher root exudation potential would exhibit enhanced P acquisition, and screened 116 diverse soybean genotypes by labelling shoots with 14CO2. A root exudation index (REI) derived from total 14C in the root exudate at sufficient (250 μm) and low (4 μm) P levels was used to classify genotypes for PAE. Genotypes with REI &gt;2.25 exhibited significantly higher exudation at low than at sufficient P, which in turn increased PAE. Under low P availability, efficient genotypes exude a greater quantity of organic compounds into the rhizosphere. This increases P availability to meet the crop requirement, enabling the crop to produce consistent biomass and seed yield with reduced fertiliser addition. Such maintenance of growth and yield potential by mining the inherent soil P is a favourable trait in genotypes, reducing dependence on P fertilisers. Measuring REI at seedling stage to select P-efficient plants accelerates the screening process by accommodating large numbers of genotypes.

The ex vitro rooting of blueberry (Vaccinium corymbosum L.) microcuttings

Abstract A growing demand for blueberry fruit has necessitated the development of an efficient propagation method of this species that would provide large quantities of planting material. The aim of this study was to evaluate the effects of auxin indole-3-butyric acid (IBA 50 mg dm−3), the commercial rooting powder Rhizopon containing 1% IBA, and salicylic acid (50 mg dm−3) on the in vivo rooting of microcuttings of Vaccinium corymbosum ‘Bluecrop’ and ‘Duke’. The contents of chlorophyll a + b, soluble proteins, free amino acids, as well as total soluble and reducing sugars were determined in rooted cuttings. All of the treatments increased the degree and percentage of rooting in the cuttings of both cultivars. While improving rhizogenesis in blueberry, salicylic acid did not perform as a cofactor of the auxin IBA. Foliar applications of IBA or salicylic acid (SA) increased the contents of soluble proteins, free amino acids and sugars, but no effects on chlorophyll levels were observed.

The Dramatic Modulatory Role of the 2'N Substitution of the Terminal Amino Hexose of Globotetraosylceramide in Determining Binding by Members of the Verotoxin Family

Although globotetraosylceramide (Gb4) is only recognized by a single member of the verotoxin family namely, the pig edema disease toxin (VT2e), removal of the acetyl group from the terminal N-acetyl hexosamine of Gb4 to generate the free amino sugar containing species (aminoGb4) results in the generation of a glycolipid preferentially recognized by all members of the verotoxin family (i.e., VT1, VT2, VT2c, and VT2e). GT3, a site-specific mutant of VT2e, in which Gb4 recognition is lost but Gb3 binding is retained, also binds aminoGb4. We have now compared the binding of VT1, VT2, VT2e, and GT3 to a series of aminoGb4 derivatives using a TLC overlay technique. DimethylaminoGb4 is bound by VT1 and VT2 but not VT2e or GT3; formylaminoGb4 binds all toxins but poorly to VT2 and preferentially VT2e; trifluoroacetylaminoGb4 binds only VT2e and GT3; isopropylaminoGb4 binds VT1 and poorly to VT2; benzylaminoGb4 binds all four toxins. Thus, there is a marked distinction between the permissible amino substitutions for VT1 and VT2e binding. GT3 is a hybrid between these in that, according to the substitution, it behaves similarly either to VT1 or to VT2e. For each species, GT3 does not however, show a hybrid binding between that of VT1 and VT2e. Analysis of the binding as a function of pH shows opposite effects for VT1 and VT2e: decreased pH increases VT1, but decreases VT2e receptor glycolipid binding.

Formation of α-dicarbonyl compounds in cookies made from wheat, hull-less barley and colored corn and its relation with phenolic compounds, free amino acids and sugars

Cookies are baked at elevated temperatures to obtain a desirable browning and flavor development, which are provided by Maillard reaction and caramelization. The drawback here is the formation of α-dicarbonyl compounds, and they are associated with many metabolic disorders besides involving in the development of the desired flavor and browning. Cookies are one of the major sources of α-dicarbonyl compounds in diet. This study was performed to evaluate the formation of α-dicarbonyl compounds in cookies prepared from different cereal flours consisting of diverse natural phenolic compounds. Flours of white wheat, hull-less barley and yellow, dark-red, blue, dark-blue colored corns containing different amount of phenolic compounds were selected as raw materials. A negative correlation was observed between total phenolic compounds and glyoxal, methylglyoxal and diacetyl concentrations after baking. α-Dicarbonyl compound-trapping ability of phenolic compounds was attributed to this reduction during baking of cookies. On the other hand, higher amounts of 3-deoxyglucosone and 1-deoxyglucosone were observed with increasing total phenolic compounds, which was in accordance with the higher sucrose hydrolysis.

Application of 1H NMR Profiling To Assess Seed Metabolomic Diversity. A Case Study on a Soybean Era Population

(1)H NMR spectroscopy offers advantages in metabolite quantitation and platform robustness when applied in food metabolomics studies. This paper provides a (1)H NMR-based assessment of seed metabolomic diversity in conventional and glyphosate-resistant genetically modified (GM) soybean from a genetic lineage representing ∼35 years of breeding and differing yield potential. (1)H NMR profiling of harvested seed allowed quantitation of 27 metabolites, including free amino acids, sugars, and organic acids, as well as choline, O-acetylcholine, dimethylamine, trigonelline, and p-cresol. Data were analyzed by canonical discriminant analysis (CDA) and principal variance component analysis (PVCA). Results demonstrated that (1)H NMR spectroscopy was effective in highlighting variation in metabolite levels in the genetically diverse sample set presented. The results also confirmed that metabolite variability is influenced by selective breeding and environment, but not genetic modification. Therefore, metabolite variability is an integral part of crop improvement that has occurred for decades and is associated with a history of safe use.

Erratum to: Analytical Methods Applied to Assess Chemical Composition, Nutritional Value and In Vitro Bioactivities of Terfezia olbiensis and Terfezia claveryi from Turkey

In this study, nutritional value, free amino acids, phenolic and sugar compounds, mineral and heavy metal contents of truffles, Terfezia olbiensis, and Terfezia claveryi from Turkey were chemically characterized using different analytical methods. In vitro antioxidant characteristics, β-carotene bleaching assay, 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity, ABTS cation radical decolorization assay, and the anticholinesterase activities, against AChE and BChE enzymes, were evaluated. Individual phenolic ingredients and free amino acids were analyzed using UPLC-ESI-MS/MS. HPLC-RID was used to assess sugar profile, and ICP-MS was used to determine minerals and heavy metals. Gentisic acid (25.48 and 14.84 μg/kg dry weight (dw)), protocatechuic acid (21.55 and 15.54 μg/kg dw), and p-hydroxy benzoic acid (18.07 and 16.99 μg/kg dw) were quantified in T. olbiensis and T. claveryi, respectively. Rhamnose, fructose, trehalose, and mannitol were the sugars identified. However, T. olbiensis and T. claveryi revealed high amounts of essential amino acids (310.25 and 314.08 mg/100 g, respectively). In addition, the ethyl acetate extracts of the mushrooms performed highest radical scavenging activity, whereas the hexane extracts of mushrooms displayed highest lipid peroxidation inhibitory activity. The results showed that the tested extracts obtained from Terfezia species can be conveniently used as sources for the protection of lipid peroxidation, free radicals, and moderate anticholinesterase agents in pharmaceutic and as food additives for extension of products’ shelf life food and dietary supplement industries. Furthermore, the techniques used in this study were easy, safe, and sensitive.

Effects of water availability on free amino acids, sugars, and acrylamide-forming potential in potato.

Irrigation is used frequently in potato cultivation to maximize yield, but water availability may also affect the composition of the crop, with implications for processing properties and food safety. Five varieties of potatoes, including drought-tolerant and -sensitive types, which had been grown with and without irrigation, were analyzed to show the effect of water supply on concentrations of free asparagine, other free amino acids, and sugars and on the acrylamide-forming potential of the tubers. Two varieties were also analyzed under more severe drought stress in a glasshouse. Water availability had profound effects on tuber free amino acid and sugar concentrations, and it was concluded that potato farmers should irrigate only if necessary to maintain the health and yield of the crop, because irrigation may increase the acrylamide-forming potential of potatoes. Even mild drought stress caused significant changes in composition, but these differed from those caused by more extreme drought stress. Free proline concentration, for example, increased in the field-grown potatoes of one variety from 7.02 mmol/kg with irrigation to 104.58 mmol/kg without irrigation, whereas free asparagine concentration was not affected significantly in the field but almost doubled from 132.03 to 242.26 mmol/kg in response to more severe drought stress in the glasshouse. Furthermore, the different genotypes were affected in dissimilar fashion by the same treatment, indicating that there is no single, unifying potato tuber drought stress response.

Selection of Drought Tolerant Groundnut Genotypes (Arachis hypogaea L.) Based on Total Sugar and Free Amino acid Content

For the selection of drought tolerant genotype, a field trial was conducted to monitor the quantitative changes of biochemical parameters such as total sugar and total free amino acid, due to water deficit condition in groundnut (Arachis hypogaea L.) seed. Plants were grown in irrigated and non-irrigated conditions. Mature seeds of forty genotypes and premature seeds of twenty one genotypes were freeze dried, defatted, ground and subjected to analysis. Drought exhibited no definite trend of increase or decrease for total free amino acid and sugar in mature as well as premature seed. Premature seed accumulated higher amount of total free amino acid having mean values 1.01% and 0.88% for control and drought respectively, than did the matured ones (control - 0.41% and drought - 0.43%). In mature seeds, drought augmented total free amino acid in twenty one genotypes and retrenched in the remaining nineteen. The data on immature seed was not much useful for selection purpose. In mature seeds of genotypes BINA-Chinabadam-2, 9267, ICGV-97228, ICGV-96295, and ICGV-95412, drought resulted in maximum elevation of total free amino acid. Accumulation of total sugar was higher in mature than in premature seeds. Drought brought about the increase in total sugar in mature seeds of thirty genotypes and decrease in the remaining ten. On imposing water stress, mature seeds of genotypes ICGV-92120, ICGV-94143, ICGV-96295, ICGV-95399 and ICGV-97228 showed comparatively high increment of total sugar. A particular genotype did not appear drought tolerant when the data on both the mature and premature seed are considered. However, in mature seed of genotype ICGV-97228, water stress induced a desired level of change in accumulation of total free amino acid and total sugar, and hence it may be preliminary considered as drought tolerant.DOI: http://dx.doi.org/10.3329/jesnr.v6i2.22077 J. Environ. Sci. &amp; Natural Resources, 6(2): 01-05 2013