Impact of egyptian broomrape (Orobanche aegyptiaca (Pers.) parasitism on amino acid composition of carrot (Daucus carota L.)

The relationship between the organic nitrogen status of Egyptian broomrape and one of its hosts, carrot, was studied by comparing amino acid profiles of leaf and root tissues of nonparasitized and broomrape-parasitized carrot plants and by analyzing amino acid profiles of broomrape at different growth stages. Total N concentrations, expressed as a percentage of the dry weight of the tissues, were similar in leaves of nonparasitized and parasitized carrot plants but were lower in parasitized roots than in nonparasitized roots. In both dry and germinated broomrape seeds, N concentrations were lower than or similar to those in broomrape tubercles, shoots, or callus. Individual amino acid concentrations in hydrolysates of leaves of parasitized carrot plants tended to be similar to or greater than those in hydrolysates of nonparasitized carrot plants. Roots of parasitized plants tended to have similar or lower amino acid concentrations than roots of nonparasitized plants. Dry and germinated broomrape seeds had similar amino acid profiles, but individual amino acid concentrations were lower than in the other broomrape tissues examined. The broomrape shoot tended to have lower amino acid concentrations than the tubercle and callus. Free amino acid profiles of leaves and roots of parasitized plants paralleled those of nonparasitized plants, respectively. Individual free amino acids tended to occur at similar or lower levels in dry and germinated broomrape seeds than in the tubercle, shoot, or callus. Free amino acid composition of the broomrape tubercle was similar to that of the parasitized root. Arginine and alanine concentrations in broomrape callus were dramatically higher than those of other amino acids in this or other tissues investigated. These results indicate that changes in the composition of both free and bound amino acids in carrot are associated with broomrape parasitism.     

Influence of soil composition on adsorption of glyphosate and phosphate by contrasting Danish surface soils

The herbicide glyphosate and inorganic phosphate are strongly adsorbed by inorganic soil components, especially aluminium and iron oxides, where they seem to compete for the same adsorption sites. Consequently, heavy phosphate application may exhaust soil's capacity to bind glyphosate, which may lead to pollution of drain‐ and groundwater. Adsorption of phosphate and glyphosate to five contrasting Danish surface soils was investigated by batch adsorption experiments. The different soils adsorbed different amounts of glyphosate and phosphate, and there was some competition between glyphosate and phosphate for adsorption sites, but the adsorption of glyphosate and phosphate seemed to be both competitive and additive. The competition was, however, less pronounced than found for goethite and gibbsite in an earlier study. The soil's pH seemed to be the only important factor in determining the amount of glyphosate and phosphate that could be adsorbed by the soils; consequently, glyphosate and phosphate adsorption by the soils was well predicted by pH, though predictions were somewhat improved by incorporation of oxalate‐extractable iron. Other soil factors such as organic carbon, the clay content and the mineralogy of the clay fraction had no effect on glyphosate and phosphate adsorption. The effect of pH on the adsorption of glyphosate and phosphate in one of the soils was further investigated by batch experiments with pH adjusted to 6, 7 and 8. These experiments showed that pH strongly influenced the adsorption of glyphosate. A decrease in pH resulted in increasing glyphosate adsorption, while pH had only a small effect on phosphate adsorption.     

Modeling protein functional properties from amino acid composition

Physicochemical and functional properties of proteins were modeled as a function of the contributions of each of the 20 coded amino acids to three (z-scores) or five (extended z-scores) amino acid principal properties using partial least squares regression. The five term models were in all cases stronger in both fit and prediction than the three term models, indicating that useful information is contained in the fourth and fifth property scores. Models predicting protein hydrophobicity (R = 0.932), viscosity (R = 0.737), and foam capacity (R = 0.880) from amino acid composition rather than sequence were obtained. It is likely that additional functional and physicochemical properties of proteins can be modeled in this way.     

Comparative study on free amino acid composition of wild edible mushroom species

A comparative study on the amino acid composition of 11 wild edible mushroom species (Suillus bellini, Suillus luteus, Suillus granulatus, Tricholomopsis rutilans, Hygrophorus agathosmus, Amanita rubescens, Russula cyanoxantha, Boletus edulis, Tricholoma equestre, Fistulina hepatica, and Cantharellus cibarius) was developed. To define the qualitative and quantitative profiles, a derivatization procedure with dabsyl chloride was performed, followed by HPLC-UV-vis analysis. Twenty free amino acids (aspartic acid, glutamic acid, asparagine, glutamine, serine, threonine, glycine, alanine, valine, proline, arginine, isoleucine, leucine, tryptophan, phenylalanine, cysteine, ornithine, lysine, histidine, and tyrosine) were determined. B. edulis and T. equestre were revealed to be the most nutritional species, whereas F. hepatica was the poorest. The different species exhibited distinct free amino acid profiles. The quantification of the identified compounds indicated that, in a general way, alanine was the major amino acid. The results show that the analyzed mushroom species possess moderate amino acid contents, which may be relevant from a nutritional point of view because these compounds are indispensable for human health. A combination of different mushroom species in the diet would offer good amounts of amino acids and a great diversity of palatable sensations.     

钼、氮肥配合施用对冬小麦子粒蛋白质及其氨基酸组成的影响

盆栽试验结果表明 ,施钼和缺钼时 ,氮肥对冬小麦的增产率分别为 319.9%和 174.0% ;冬小麦子粒中蛋白氮、清蛋白氮、醇溶蛋白氮含量 ,面粉蛋白质氨基酸总量及其氨基酸组分的含量以及谷氨酸、脯氨酸的比例等随氮肥水平提高而增加 ;但冬小麦面粉中游离天门冬氨酸和苏氨酸的含量和比例降低 ,游离氨基酸含量在缺钼时提高了 38.3% ,施钼时则下降了 37.1%。在高、低氮肥水平下施钼 ,冬小麦子粒中蛋白质含量没有明显影响 ,但分子量小的蛋白质含量及其占总量的比例下降 ,清蛋白比例分别下降 14.5、6.6个百分点 ;而大分子量蛋白质含量和比例均提高。在不同施氮水平下缺钼冬小麦子粒中游离氨基酸含量比施钼分别高 48.0%和 15.26% ,且亲水性氨基酸比例增加。缺钼冬小麦子粒中低分子量蛋白质、游离氨基酸以及亲水性氨基酸的增加 ,可能是诱发缺钼冬小麦子粒低休眠度以及出现收获前萌芽的重要原因。     

Soil amino acid composition quantified by acid hydrolysis and anion chromatography-pulsed amperometry

Soil organic N accounts for 95-98% of the total soil N content with amino acids (AAs) and amino sugars (ASs) identified as the major soil organic N compounds, but traditional 6 M HCl with reflux or sealed digestions for 24 h and various detection systems have accounted for only 30-40% of soil total N content as AA-N. This study compared traditional HCl extraction methodology with methanesulfonic acid (MSA) hydrolysis and nonderivatized AA and AS quantification by ion chromatography with pulsed amperometric detection for determination of the AA composition of plant litter and soils. MSA (4 M) gave AA-N recovery comparable to or better than 6 M HCl for plant AA digestions (16 h, 121 degrees C, 104 kPa). Use of 4 M MSA (0.5-1.5 h, 136 degrees C, 112 kPa) increased the total recovery of organic N as AAs, ASs, and NH(4)(+) by 46% from soils (n = 22) compared with 6 M HCl (12 h, 110 degrees C, reflux) with a MSA recovery rate of 85.6% of the total N content (n = 22 soils). The shorter MSA soil digestions (0.5-1.5 h) suggested that the majority of soil organic N was not present as protein forms found in plant litter analysis (16 h of digestion). MSA ion chromatographic analysis for soil AA/AS composition is a robust nonderivatization method requiring little sample preparation that can distinguish between small changes in soil AA composition during one growing season due to vegetation and tillage managements.     

Effect of nitrogen nutrition on the free amino acid composition in tobacco plant

Nitrogen nutrition has great influences not only on the growth, but also on leaf quality of tobacco. There have been many reports on the nitrogen nutrition of tobacco, in which various nitrogen constituents such as amino acids and related compounds have been analyzed. But definite conclusions were often hard to be drawn out, since sometimes the work was limited by the failure of finding suitable chemical techniques. The recent development of paper chromatographic methods, however, has made possible to detect the individual amino acids, and has provided a new approach to the study of nitrogen nutrition of tobacco. Using the paper chromatographic techniques, the effects of nitrogen form, the effect of sulfur nutrition and excess of chlorine on free amino acid composition of tobacco leaf have been reported by the authors (1). The next step of the work presented here was undertaken for the quantitative study of the effect of nitrogen nutrition on free amino acid content of tobacco cultured for commercial purpose employing the amino acids estimation method developed by MOORE and STEIN (2) (3).     

Soil amino acid composition across a boreal forest successional sequence

Soil amino acids are important sources of organic nitrogen for plant nutrition, yet few studies have examined which amino acids are most prevalent in the soil. In this study, we examined the composition, concentration, and seasonal patterns of soil amino acids across a primary successional sequence encompassing a natural gradient of plant productivity and soil physicochemical characteristics. Soil was collected from five stages (willow, alder, balsam poplar, white spruce, and black spruce) of the floodplain successional sequence on the Tanana River in interior Alaska. Water-extractable amino acid composition and concentration were determined by HPLC. Irrespective of successional stage, the amino acid pool was dominated by glutamic acid, glutamine, aspartic acid, asparagine, alanine, and histidine. These six amino acids accounted for approximately 80% of the total amino acid pool. Amino acid concentrations were an order of magnitude higher in coniferous-dominated late successional stages than in early deciduous-dominated stages. The composition and concentration of amino acids were generally constant throughout the growing season. The similar amino acid composition across the successional sequence suggests that amino acids originate from a common source or through similar biochemical processes. These results demonstrate that amino acids are important components of the biogeochemical diversity of nitrogen forms in boreal forests.     

Basic composition and amino acid contents of mushrooms cultivated in Finland

The basic composition (moisture, total carbohydrates, dietary fiber, crude fat, ash, nitrogen, and protein) and amino acid contents were determined in the cultivated mushrooms Agaricus bisporus/white, Agaricus bisporus/brown, Lentinula edodes, and Pleurotus ostreatus. In addition, nitrogen-to-protein conversion factors were calculated for each species by dividing the sums of amino acid residues with total (Kjeldahl) nitrogen contents. The dry matter contents of mushrooms varied from 7.7% to 8.4%. The dry matter of mushrooms contained large amounts of carbohydrates, from 4.5 (A. bisporus/white) to 5.8 g/100 g fresh weight (L. edodes). L. edodes proved to be an especially good source of dietary fiber (3.3 g/100 g fresh weight); the other mushrooms contained 1.5-2.4 g/100 g fresh weight. Crude fat, ash, and protein (based on amino acid analysis) contents of the mushrooms varied 0.31-0.35, 0.49-0.78, and 1.8-2.09 g/100 g fresh weight, respectively. Mushrooms proved to be good sources of almost all essential amino acids when compared with common vegetables. The mean nitrogen-to-protein conversion factor analyzed in the present study was 4.7 +/- 0.21. When using this factor, a very good estimation of protein contents could be obtained for the main species of mushrooms cultivated in Finland.     

Egyptian broomrape (Phelipanche aegyptiaca) response to silicon nutrition in tomato (Solanum lycopersicum L.)

Egyptian broomrape is a root holoparasitic plant that causes severe damage to tomato in Iran. Experiments were conducted in 2013 to investigate the effect of silicon (Si) nutrition on broomrape response in tomato. Si concentration significantly delayed first appearance of broomrape and decreased number of tubercles in both cultivars, although the magnitude of reduction varied with cultivar and Si concentration. Broomrape infection significantly decreased root and shoot dry weights of tomato cultivars. However, Si nutrition at high concentration considerably reduced damage severity of broomrape compared to the treatment that received no Si. Infection of tomato with broomrape resulted in significant increase in peroxidase and catalase activity in the roots of resistant cultivar which led to enhanced crop resistance to oxidative stress and improved growth in this cultivar.     

施氮对稻米蛋白质、氨基酸含量的影响

稻米蛋白质和各种氨基酸含量是稻米营养价值的一个重要指标,尤其是人体不能合成的赖氨酸含量的高低对稻米的营养价值更为重要.本项试验通过分析研究不同施氮量以及等氮量条件下水稻生长前、中、后期不同施氮比例对稻米中蛋白质和各种氨基酸含量的变化,以探讨不同施肥方法对稻米营养价值的影响,为高产、高效、优质的水稻施肥提供依据.     

Mineral nutrient and amino acid composition of certain tropical cultivars of soybean

Mineral nutrient and amino acid composition of twelve varieties of soybean grown in an alluvial soil under tropical climate of Assam, India, were studied. On a dry weight basis, Ca and K contents were between 0.35 to 0.46% and 1.66 to 2.11%, respectively, which were relatively high compared with those in temperate varieties. Protein content of the soybeans varied between 40 to 48%. SL‐96 showed the highest amounts of K, Zn, Mn, and B; DS‐37 contained the maximum total amino acids and protein. On the basis of nutrient contents, SL‐96 and DS‐37 are recommended for cultivation in Assam.     

Carbohydrate and amino acid composition of dissolved organic matter leached from soil

Low molecular weight organic substances (LMWOS) in soil and soil solution include mainly amino acids, carboxylic acids, and carbohydrates. Due to their high bioavailability they play a crucial role in the cycles of C and nutrients in soils. The variety of soil processes that involve LMWOS requires identifying their composition to elucidate reactions and transformations. In most studies, LMWOS are extracted under artificial conditions, e.g. batch experiments, which may overestimate the actual concentrations. This study measures the composition of carbohydrates and amino acids in solution of a Haplic Luvisol leached in a column experiment. A combined system for simultaneous leaching and blowout of CO₂ was used to estimate LMWOS decomposition. ¹⁴C-labeled glucose was added as a highly sensitive tracer to control the efficiency of the LMWOS extraction by leaching and to estimate LMWOS decomposition during leaching. High performance liquid chromatography (HPLC), optimized for soil extracts, was used to analyze LMWOS composition. For HPLC optimization, different preparations of leached solutions (filtration vs. centrifugation, and drying vs. no-drying) were compared. For sugar determination, drying had no influence on the solution concentrations. In contrast, amino acid concentrations significantly decreased by drying LMWOS eluted substances. Combining the HPLC identification of eluted substances with ¹⁴C tracer application revealed that about 5% of the glucose could be leached unchanged within 786 min (13.1 h), whereas about 84% remained in the soil, 9% were decomposed to CO₂, and 2% were transformed to other LMWOS and recovered in the soil solution. The total amino acid concentration (TAC) in soil solution was about 8.2 μmol l⁻¹, dominated by alanine (14.4% of TAC), glycine (13.4%), glutamic acid (9.9%), serine (9.4%), and leucine (9.3%). The total carbohydrate concentration was about 2.4 μM, dominated by glucose (29.9%), glucuronic acid (26.8%), and galacturonic acid (17.3%). Ratios of hexoses to pentoses, amino sugars glucosamine to galactosamine, and neutral sugars to uronic acids were determined. All three parameters pointed to the dominant influence of plants as the source of LMWOS in the leached soil solution. Within the small contribution of microorganisms, bacteria dominated over fungi. These used biomarker ratios as well as LMWOS concentrations differed widely from the ones obtained with conventional batch extraction. More research is necessary to evaluate the application of these biomarkers to soil solutions.     

Changes of amino acid composition and lysinoalanine formation in alkali-pickled duck eggs

Duck eggs were pickled in alkali for 20 days to prepare Pidan. The extent of the degradation of compositional amino acids, the formation of lysinoalanine (LAL) in Pidan, and the relationship between the formation of LAL and the racemization values of D-serine and D-aspartic acid in Pidan albumen during the pickling period were investigated. Results showed that the remaining percentages of Cys, Arg, Lys, Ser, and Thr in albumen were much lower than that of the corresponding amino acid in yolk. The formation of LAL in albumen in the first stage was due to the speedy increase in the pH and the abundant formation of dehydroalanine (DHA) from cysteine. However, the formation of LAL in the later pickling period was related much more to the alkali-treating time than to the pH factor. Among the amino acids, cysteine was observed to be the most sensitive to alkaline and contributed mostly to the formation of LAL throughout the pickling period.     

基于伪氨基酸和支持向量机的蛋白质亚细胞定位预测

用电子—离子伪势能(E IIP)对蛋白质序列数字化,经离散傅立叶变换(DFT)后,取5个最高幅值对应的频率和20种氨基酸在序列中所占的百分比组成伪氨基酸。用支持向量机(SVM)方法得到分类的模型,并用几个标准的测试方法测试模型的性能。自身一致性测试和Jackkn ife测试均取得高的预测准确率,独立数据集测试的准确率超过80%。和之前报道的方法相比,本方法具有较高的预测准确率。     

玉米与赤霉素对向日葵列当种子萌发、防除以及对后茬作物向日葵生长的影响

向日葵列当(Orobanche cumana Wallr.)是一种根寄生草本植物,对向日葵等经济作物造成严重危害。为了减少向日葵列当对向日葵的寄生,降低土壤中向日葵列当种子库,本试验以新疆地区广泛种植的玉米品种‘京糯一号’和‘新玉57号’为研究材料,通过穴盘试验研究在不同时期(出苗后10 d和15 d)施加两种不同浓度赤霉素(10~(-4 )mol·L~(-1)和10~(-5 )mol·L~(-1))对上述两个品种玉米生长发育和分泌列当萌发刺激物质的影响;24 d后收集并提取玉米根系分泌物,用其进行刺激向日葵列当种子的萌发试验,从而筛选出刺激向日葵列当种子萌发能力较强的玉米品种进行盆栽试验。通过盆栽试验,在玉米种植后的不同时期(20 d和40 d)喷施10~(-4 )mol·L~(-1)赤霉素以探究玉米与赤霉素共同防除向日葵列当种子的效果,收获时(105 d后)采集玉米地上部、根和根际土样品,用其甲醇浸提液刺激向日葵列当种子萌发;次年在种植过玉米的盆中种植后茬作物向日葵,收获时测定向日葵的农艺指标并统计向日葵列当的出土数。结果表明:穴盘试验中施加赤霉素对玉米的株高有显著增高作用,对玉米根系分泌萌发刺激物质没有抑制作用,即在玉米生长时期可以施加10~(-4 )mol·L~(-1)和10~(-5 )mol·L~(-1)赤霉素。此外,‘新玉57号’根系分泌物的100倍稀释液刺激向日葵列当种子的萌发率显著高于‘京糯一号’,因此选取‘新玉57号’作为盆栽试验的玉米品种。盆栽试验中不同时期施加10~(-4 )mol·L~(-1)赤霉素,玉米株高同样显著高于对照,增长率分别为22.5%、19.1%。次年种植后茬作物向日葵,在第20 d向玉米施加赤霉素处理的盆中种植的向日葵的花盘直径比对照(种植玉米时不施加赤霉素)显著增加57.1%。与对照相比,在种植玉米后的20 d和40 d施加赤霉素的处理种植向日葵,向日葵列当的出土数分别是1.3个·盆~(-1)、1.8个·盆~(-1),分别降低76.4%和67.3%。因此,可以在玉米种植的后20 d和40 d施加10~(-4 )mol·L~(-1)赤霉素,与玉米共同诱导向日葵列当种子"自杀发芽",以减少向日葵列当对向日葵植株的危害。     

Influence of crops, crop residues and manure on amino acid and amino sugar fractions of organic nitrogen in soil

A field experiment was carried out to study the effect of: (1) the cultivation of a cereal (pearl millet) and two legumes (mung bean and clusterbean), and (2) incorporation of crop residues and manure in soil, on depletion or enrichment of pools of amino acid-N and amino sugar-N in soil. Both legumes enriched amino acid and amino sugar fractions but pearl millet cultivation depleted them. Enrichment of these fractions was partly attributed to the conversion of N biologically fixed during legume cultivation to these fractions and partly to the conversion of unknown and non-hydrolysable N fractions to amino acid-N and amino sugar-N. Mineralization of amino acid-N and amino sugar-N fractions along with their conversion to unknown and non-hydrolysable fractions were the plausible reasons for the decline in their concentrations after pearl millet cultivation. Application of residues or manure reversed this effect of pearl millet.