Protein content and amino acid spectrum of finger millet [Eleusine coracana (L.) Gaertn.] as influenced by nitrogen and sulphur fertilizers

Summary The effect of N and S fertilizers on yield, protein content and amino acid composition of the tropical cereal finger millet was studied in field and sand culture experiments. In the field the grain yield measured from 2400 to 4100 kg/ha, and the seed crude protein from 7 to 13% with rates of N up to 150 kg/ha. Seed crude protein was high in methionine and cystine, but contained less sulphur amino acids when the seed was high in protein.Supplies in excess failed to increase the lower methionine and cystine contents of the crude protein.Sulphur deficiency drastically reduced the synthesis of sulphur amino acids, concomitantly raising the aspartic acid/asparagine content of the leaves up to 45 per cent of their total N content. An S:N weight ratio of 1:10 in the seeds and 1:15 in the leaves indicates adequate supply of sulphur. The importance of finger millet for human nutrition is considered in relation to increasing substitution with other crops, use of nitrogen fertilizers, and the actual sulphur status of soils in East Africa.Sponsored by the Norwegian Agency for International Development.Sponsored by the Norwegian Agency for International Development.     

The effect of copper and nitrogen on the amino acid composition of oat straw

Summary The effect of fertilization with nitrogen and copper on the amino acid composition of oat straw has been studied.The plants (Avena sativa cv Yielder) were grown in peat with a very low copper content and supplied with two levels of nitrogen (NH₄ or NO₃) and three levels of copper sulphate.The higher level of nitrogen stimulated growth only when copper was added, whereas, without copper, it had an adverse effect on growth and prevented grain formation altogether. The higher level of nitrogen increased the nitrogen content of the straw at all levels of copper, but particularly in plants receiving no copper.Total amino acids in the straw hydrolysate of copper sufficient oats accounted for about 50% of the total N and was about 20% higher in copper-deficient tissues. The addition of copper caused a decrease in the amounts of all amino acids. The relative proportions of most of the amino acids to glycine remained fairly constant. Threonine, serine, alanine, iso-leucine, histidine and arginine showed small significant differences with copper treatment, whereas valine, tyrosine, phenylalanine, proline, lysine and cysteic acid (derived from cysteine and cystine) showed no differences. The proportion of aspartic acid relative to glycine in the straw hydrolysate was greatly increased in copper deficient plants supplied with the higher level of nitrogen, particularly as ammonium. The proportion of glutamic acid was also increased by the higher level of nitrogen, but showed no effect of added copper. Most of the difference in aspartic acid could be accounted for as free asparagine. The possible reasons for higher proportions of asparagine are discussed in relation to the metabolism of the oat plant.     

Impact of potassium,sodium, and salinity on the protein-and free amino acid content of wheat grain

A lysimeter study was conducted on Cajeme wheat (Triticum aestivum L.) to investigate the impact of salinity on protein and free amino acid content of the grain. Cross correlations were obtained between 16 different soil-plant-water based parameters and the concentration and total accumulation of amino acids. The results indicated that after 3 years of irrigation, the majority of protein bound and free amino acids increased in concentration in the grain. However, both free tryptophan and free proline revealed decreasing concentrations with increasing salinity. Free tryptophan showed a synergism between total accumulation, yield and concentration. Free proline concentrations decreased in association with increasing protein concentrations. Cross correlations of the 16 soil-plant-water based parameters with free and protein bound amino acids revealed significant correlations for free aspartic acid and glycine with total accumulation but not with concentrations. Only methionine plus cystine was lower than suggested FAO levels for essential amino acids and was lower in the third year than in the first year.     

不同施氮量对乌龙茶生长和生理的影响

以武夷肉桂为研究对象,研究不同施氮量对乌龙茶幼龄茶树生长和生理的影响。结果表明,幼龄茶树对氮肥的需求不强烈,其新梢生物量、根生物量和总生物量以及茶叶产量随施氮量的增加而下降。茶树新梢全氮、叶绿素、游离氨基酸、茶多酚和咖啡碱的含量随施氮量的增加而增加,而茶树碳氮比随着施氮量增加而下降;但施氮并没有影响茶树总碳含量。老叶叶绿素含量、根全氮和硝态氮含量、新梢总糖含量与施氮量呈二次曲线回归关系,适度施氮促进根对氮的吸收、老叶叶绿素合成和新梢总糖代谢,过度施氮则相反。新梢生物量与其硝态氮含量和游离氨基酸总量显著负相关;根生物量与根碳氮比和新梢咖啡碱含量显著负相关;茎叶生物量和总生物量与根含氮量显著正相关,但与新梢硝态氮和氨基酸含量显著负相关。过度施氮造成茶树生产力下降的主要原因是因为过度施氮极显著提高了茶树氨基酸代谢水平,使用于茶树生长的碳代谢产物（如总糖）减少,进而影响茶树的生长。     

施氮水平对小麦籽粒发育过程中氨基酸含量的影响

施氮能提高小麦籽粒蛋白质氨基酸的含量,并与施氮水平呈正相关;但对普通小麦必需氨基酸与蛋白质氨基酸的比值没有影响,而硬粒小麦4286随施氮水平的提高,该比值下降。在开花后32d以前,籽粒发育过程中游离氨基酸与施氮水平呈正相关,以后,籽粒中游离氨基酸趋于相近,表明施氮增加了游离氨基酸的库源,不同基因型小麦对施氮水平的反应不同,在同等施氮水平和栽培条件下,籽粒中蛋白质氨基酸和游离氨基酸含量为硬粒小麦4286＞小偃6号＞小偃107,不同施氮水平下,籽粒中氨基酸含量为高氮＞中氮＞低氮。     

Effect of nitrogen nutrition on amino acid composition of xylem sap and stem wood in Alnus glutinosa

Citrulline was the major amino acid in root pressure sap, stem sap and stem wood from Alnus glutinosa L. Gaertn. plants relying on fixed nitrogen or, partly or wholly, on mineral nitrogen for growth. Glutamine increased in prominence in plants assimilating mineral nitrogen but asparagine remained a relatively insignificant component. Differences in the relative amounts of the free amino compounds of stem sap from nitrogen-fixing and mineral nitrogen-fed plants were usually small compared to differences between plants fed different sources of mineral nitrogen. In contrast, relatively high values for the ratios of citrulline/total free amino nitrogen compounds and particularly of citrulline/amides in root pressure sap distinguished nitrogen-fixing plants from those receiving mineral nitrogen. Although the amino acid ratios of stem wood extracts showed closer similarity to those for root pressure sap than stem sap, the seasonal accumulation of citrulline, possibly as a storage amino acid, in stem wood from field-grown plants negated the possibility of utilising stem wood analyses as an indicator of the form of nitrogen assimilation. Comparative data on the levels of citrulline or other free amino acids in Alnus glutinosa are unlikely to be useful as an index of nitrogen fixation, under most experimental conditions.     

Relationship between sulphur content of leaf with methionine,cysteine and cysteine contents in the seeds ofPhaseolus aureus L. As affected by S,P, and N application

Summary The sulphur content in leaves increased with increasing levels of sulphur and with the advancement of age and was maximum at 50 days stage and declined towards maturity. There was a significant positive correlation between sulphur content of leaf at various stages of growth and sulphur-containing amino acids viz. methionine, cystine, and cysteine in seed. The sulphur containing amino acids in seeds also increased with increasing levels of sulphur upto 90 ppm and with further increase in the dose it decreased.     

Sulphur and nitrogen nutrition influence the response of chickpea seeds to an added, transgenic sink for organic sulphur

In order to increase the concentration of the nutritionally essential sulphur amino acids in seed protein, a transgene encoding a methionine- and cysteine-rich protein, sunflower seed albumin (SSA), was transferred to chickpeas (Cicer arietinum L). Transgenic seeds that accumulated SSA contained more methionine and less oxidized sulphur than the controls, suggesting that additional demand for sulphur amino acids from the expression of the transgene stimulated sulphur assimilation. In addition, the activity of trypsin inhibitors, a known family of endogenous, sulphur-rich chickpea seed proteins, was diminished in transgenic, SSA-containing seeds compared with the non-transgenic controls. Together, these results indicate that the reduced sulphur sequestered into SSA was supplied partly by additional sulphur assimilation in the developing transgenic seeds, and partly by some diversion of sulphur amino acids from endogenous seed proteins. Growth of chickpeas on nutrient with a high sulphur-to-nitrogen ratio increased the total seed sulphur content and the accumulation of sulphur amino acids in the seeds, and partly mitigated the effect of SSA accumulation on the trypsin inhibitor amount. The results suggest that free methionine and O-acetylserine (OAS) acted as signals that modulated chickpea seed protein composition in response to the variation in sulphur demand, as well as in response to variation in the nitrogen and sulphur status of the plant.     

Plant nitrogen status rapidly alters amino acid metabolism and excretion in Bemisia tabaci

The effect of plant nitrogen (N) status on the content and distribution of free amino acids in the bodies and honeydew of silverleaf whiteflies Bemisia tabaci (Gennadius) Biotype B (= B. argentifolii Bellows and Perring) was determined. Whiteflies fed for 4 days on cotton leaves that received high or low N fertility. For low-N plants, photosynthesis and leaf total N levels were decreased, and a much-reduced amount of free amino acids was recovered in phloem sap. Low N fertility did not affect whitefly total N content, but did markedly decrease the free amino acid content. Glutamine, alanine and proline accounted for over half of the insect free amino acid pool for both N treatments. On a relative basis, adjustments in glutamine levels in response to plant N status were much larger compared to the other amino acids. Large amounts of amino N, especially asparagine, were excreted from whiteflies fed on high-N plants whereas amino N excretion essentially ceased for whiteflies fed on low N plants. The distribution of amino acids in the insects and honeydew was not closely related to the phloem sap amino acids. However, total amino acid excretion was quite indicative of the plant N status and the quality of the insect diet. The results indicated that whitefly free amino acid pools and excretion of amino N were rapidly altered by plant N status.     

The influence of organophosphoric insecticides on total nitrogen and free amino acid levels in the leaves of apple seedlings

The effect of 0.1% Metation E 50 (fenitrothion) and Fosfotion 50 (malathion) on the level of total nitrogen and that of free amino acids was investigated in juvenile and mature leaves of apple seedlings in the course of six days following treatment. Fosfotion affected both nitrogen and amino acid content to a higher degree than Metation. Fosfotion increased the total nitrogen content in all leaves, but Metation induced the change only in the leaves which were at the end of the logarithmic growth phase at the time of treatment. The level of amino acids increased on the whole, with the exception of a temporary decline in the youngest leaves as well. The treatment with both insecticides affected most the content of amides: the greatest decrease of glutamine occurred in young leaves, the highest increase in asparagine content was recorded in both juvenile and mature leaves.     

Protein and free amino acids in wheat grain as affected by soil types and salinity levels in irrigation water

Summary The effects of four lysimeter soil series under three salinity levels were evaluated for grain yield, wt/1000 seeds, protein, and amino acids in Mexican dwarf wheat (Triticum aestivum L. var. Cajeme 71). The soil series consisted of: Holtville clay loam, Greenfield sandy loam, San Emigdio sandy loam, and Altamont clay loam. The irrigation water salinity levels were designated: low –2.2 mmho, medium –4.2 mmho, and high –7.1 mmho.No significant differences were found in the amount of grain harvested or wt/1000 seeds in the 1976 crop produced on the differential soil series. The yield of the 1977 crop was significantly affected by the soil types.Effects of soil type on the protein amino acids in the grain in both years were similar. Significantly higher protein amino acid levels of histidine, arginine, aspartic acid, threonine, serine, glutamic acid, glycine, alanine, cystine, valine, methionine, isoleucine, leucine, tyrosine, and phenylalanine were found in the grain grown on Altamont clay loam soil than the other types.The free amino acids in grain from the 1976 and 1977 crops were similarly affected by the soil types, except that the quantitative values of the free amino acids were substantially lower in 1977 than in 1976. The free amino acids significantly influenced by soil types were tryptophane, lysine, arginine, aspartic acid, threonine, serine, glycine, alanine, valine, isoleucine, tyrosine, and phenylalanine. In both years' crops, the sum of the free amino acid fractions was significantly higher in the grain produced on the Altamont soil than on the other soils.Salinity level in the irrigation water did not affect the 1976 crop yield or wt/1000 seeds. Although yields of the 1977 crop were significantly reduced by salinity, the wt/1000 seeds was not. The sum of protein amino acids was significantly higher in the 1976 and 1977 grain crops irrigated with high salinity water than in low salinity irrigated crops.An increased salinity irrigation water significantly reduced the sum of free amino acid fractions in the 1976 grain crop. Since some of the free amino acids in the 1977 grain crop increased while the others decreased due to the salinity level in the irrigation water, the sum of the free amino acid fractions was not significantly influenced.Significant interactions were found between soil types and salinity levels on free arginine, threonine, serine, glutamic acid, and alanine, and also on the sum of the free amino acids in the 1976 wheat grain. In the 1977 wheat grain, there were significant interactions between soil types and salinity levels on the free glutamic acid, valine, leucine, tyrosine, and phenylalanine, and on protein serine, glutamic acid, glycine, alanine, and the sum of the protein amino acids.The amounts of essential amino acids expressed as mg of amino acid/g of protein were not affected by the soil types or salinity levels. With the exception of lysine, and possibly threonine and methionine plus cystine, the essential amino acids were present in the grain at concentrations equal to or greater than recommended by WHO and FAO.     

Studies on Rice Glutelin

The complete amino acid analysis of the whole glutelin preparation from rice endosperm was performed. The recoveries were 101.59% for amino acid residues and 101.68% for nitrogen, and the standard deviations for four determinations on the 22 and 70 hr hydrolyzates were very small. The features of the amino acid composition of the protein were as follows; (1) the high contents of dicarboxylic amino acids, particularly glutamic acid, (2) about 60% of these dicarboxylic amino acids was in the amide form, and (3) the significantly low contents of tryptophan, methionine and half cystine. The amino acid analyses of the two kinds of the subunits of glutelin, the neutral major one and the basic minor one, were also carried out. There were some significant differences between the two subunits, for instance, in the contents of glutamic acid, tryptophan, glycine, half cystine, methionine and lysine. However, the composition of whole glutelin seemed to be settled predominantly by that of the major subunit.     

Free amino acids and total nitrogen during shoot development in Scots pine seedlings

The concentration of free amino acids and total nitrogen was studied in needles, stems and roots of seedlings of Pinus sylvestris L. for five weeks during the second growth period ("summer"). In one group of seedlings the source/sink relation was disturbed through removal of the terminal buds. The seedlings were cultivated in artificial year-cycles in a climate chamber.
Total nitrogen increased in needles and sterns of intact seedlings in the beginning of the "summer" and decreased during shoot growth. In seedlings, from which the buds had been removed, nitrogen remained at high levels in the primary needles and accumulated in steins and roots. The results are consistent with utilization of nitrogen in older needles and in the stem during shoot elongation.
The pool of free amino acids increased in the beginning of the "summer" and decreased after bud break in primary needles, stems and roots. Arginine and glutamine, in the roots also asparagine, were the dominating amino acids (amides included). Together, these compounds (plus glutamate and aspartate) contributed about 90% of the nitrogen in the amino acid pool in all organs. In primary needles and in the stem, arginine predominated at the end of hardening (75–85% of the amino acid nitrogen). Free amino acids contributed at most ca 10% of the total nitrogen in primary needles, where the ratio of free amino acid nitrogen: total nitrogen was highest at the end of dormancy and in the early "summer". Free amino acids accumulated after bud removal in primary needles and especially in stems and roots. Glutamine became relatively more dominant than arginine in the different organs.
The observations are consistent with the role of arginine and glutamine for storage and transport of nitrogen in conifers. Because of the low concentrations of amino acid nitrogen in the primary needles, arginine is not considered a major nitrogen reserve in needles of Scots pine seedlings.     

Enhanced photosynthetic capacity increases nitrogen metabolism through the coordinated regulation of carbon and nitrogen assimilation in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Plant growth and productivity depend on interactions between the metabolism of carbon and nitrogen. The sensing ability of internal carbon and nitrogen metabolites (the C/N balance) enables plants to regulate metabolism and development. In order to investigate the effects of an enhanced photosynthetic capacity on the metabolism of carbon and nitrogen in photosynthetically active tissus (source leaves), we herein generated transgenic Arabidopsis thaliana plants (ApFS) that expressed cyanobacterial fructose-1,6-/sedoheptulose-1,7-bisphosphatase in their chloroplasts. The phenotype of ApFS plants was indistinguishable from that of wild-type plants at the immature stage. However, as plants matured, the growth of ApFS plants was superior to that of wild-type plants. Starch levels were higher in ApFS plants than in wild-type plants at 2 and 5 weeks. Sucrose levels were also higher in ApFS plants than in wild-type plants, but only at 5 weeks. On the other hand, the contents of various free amino acids were lower in ApFS plants than in wild-type plants at 2 weeks, but were similar at 5 weeks. The total C/N ratio was the same in ApFS plants and wild-type plants, whereas nitrite levels increased in parallel with elevations in nitrate reductase activity at 5 weeks in ApFS plants. These results suggest that increases in the contents of photosynthetic intermediates at the early growth stage caused a temporary imbalance in the free-C/free-N ratio and, thus, the feedback inhibition of the expression of genes involved in the Calvin cycle and induction of the expression of those involved in nitrogen metabolism due to supply deficient free amino acids for maintenance of the C/N balance in source leaves of ApFS plants.     

Morphogenesis and free amino acid composition of the ascomycete Sphaerostilbe repens as influenced by nitrogen and calcium

Abstract Sphaerostilbe repens utilizes nitrate and ammonium as nitrogen sources. Differentiation of mycelium into rhizomorphs and coremia was reduced in the presence of nitrate and completely inhibited in the absence of calcium. The most abundant free amino acids were, in decreasing order: alanine, glutamine, glutatomic acid, serine, aspartic acid, γ-aminobutyric acid, arginine and threonine. These compounds represented 90% of the total amino acid pool.
The free amino acid composition did not vary with cultural conditions although concentrations of individual amino acids differed. In ammonium-grown cells, γ-aminobutyric acid increased in concentration and glutamate, aspartate and alanine decreased. Calcium-deficient media reduced amino acid concentrations, especially of arginine and ornithine. Amino acid contents increased during the growth period and were higher in rhizomorphs than in vegetative mycelia.     

The effect of manganese and EDTA on the balance of nitrogen in maize xylem exudate

The effect of manganese chloride (10 mg Mn l^-1), EDTA (18 mg l^-1) and a mixture of these compounds on the nitrogen balance in maize xylem exudate was investigated. The compounds were applied as experimental solutions to the roots of 20 day old plants 24 h before excision. Application of Mn resulting in a lowered nitrogen level in the xylem exudate increased the relative content of the organic N-compounds in the exudate, particularly that of free amino acids. EDTA appreciably enhanced the content of total nitrogen in xylem exudate, however no significant changes were found in the proportion of inorganic and organic N-compounds in comparison with the water control. The significant features of the free amino acid exudate fraction of all experimental variants were, among others, the relatively high lysine content and the absence of proline arid sulphur containing amino acids. By gel filtration on Sephadex G-25 of xylem exudates UV (254 nm) absorbing fractions, four in the water control, five in Mn and six in EDTA variants were isolated. The UV absorbing fractions with the exception of one in each experimental variant (K_av 0.73 in water control, K_av 0.61 in Mn-variant, K_av 0.75 in EDTA and Mn + EDTA variant) were of peptide character, proline and sulphur-containing amino acids were missing in them. In the exceptional UV absorbing fractions (K_av 0.61–0.75) in spite of their high N-content (10.23%) after hydrolysis practically no amino acid could be detected.     

The effect of nitrogen source on levels of amino acids in peas

Summary When nitrogen fixation in peas was partially replaced by nitrate assimilation as the source of nitrogen, an increase was found in the amount of soluble nitrogen that could be extracted from the fruits of the plants, and within this soluble fraction, increases were found in the levels of some of the acidic amino acids. Levels of protein amino acids in the peas were generally unaffected by the type of nitrogen source except for the level of aspartic acid which was about 20 per cent lower in peas supplied with nitrate. No differences were found in the proportions of the essential amino acids.     

Protein and free amino acids in field-grown cowpea seeds as affected by water stress at various growth stages

Summary This study was undertaken to evaluate water stress effects during vegetative, flowering, and podfilling stages of cowpea plants (Vigna unguiculata L.) grown under natural field conditions in southern California on seed yield and protein and free amino acid content of the cowpea seeds. The lowest concentration of N was found in the seeds of the control treatment plants while the seed yield from these treatments was the highest as compared with the N concentration and yield of seeds from plants subjected to water stress during flowering and podfilling stages. The concentration of N in the seeds was inversely related to the seed dry weight yield. Protein arginine,-threonine,-serine,-cystine,-valine,-methionine, and-isoleucine were significantly affected by water stress at the three growth stages. There was no consistent pattern in the effect of water stress on the individual amino acids. The sum of protein amino acids in the cowpea seeds was not significantly influenced by the various treatments since some of the protein amino acids increased and others decreased producing an averaging effect on the figures comprising the sums of the amino acids. Water stress during the flowering and pod-filling stages increased the free amino acid pool, and at the same time, inhibited incorporation of the amino acids into the protein chain-thus lowering the protein amino acid fraction simultaneously. With the exception of methionine plus cystine, the essential amino acids in the seeds were present at concentrations equal to or greater than recommended by the World Health Organization and FAO. It is of particular importance to note that the concentration of lysine in the cowpeas was substantially higher than that found in wheat grain. It is also important to note that the amount of essential amino acids per gram of protein was not measurably affected by the water stress treatments during any of the growth stages.     

C14 distribution in photosynthate of tomato as influenced by substrate copper and molybdenum level and nitrogen source

Summary The influence of nitrogen source and micronutrient treatment on the apportionment of C¹⁴ in alcohol extracts was studied in tomato. Plants were exposed at several stages of maturity to C¹⁴O₂ and the ethanol-soluble photosynthate fractionated into sugars, organic acids, and amino acids.Ammonium-treated plants had low levels of organic acids at all stages of maturity, suggesting a rapid conversion to amino acid residues. However, the addition of copper in the absence of molybdenum resulted in increased labelling of the organic acid fraction under nitrate nutrition. The amino acid fraction was reduced at some stages of growth under these conditions. This may indicate that copper interferes with the role of molybdenum in the enzymatic reduction of nitrate.Measurement of the total quantity of some individual free amino acids indicated more efficient utilization of these for protein synthesis in the presence of copper. On the other hand, assay of the C¹⁴-activity of individual free amino acids showed that degree of label bore little relation to micro-nutrient treatment.Plant Science Department and Botany Department, University of Connecticut. Scientific Contribution No. 116, Agricultural Experiment Station, University of Connecticut, Storrs. This paper is based on a portion of the senior author's Ph. D. thesis (University of Connecticut).