Control of Seed Protein Accumulation in Field Bean (Vicia faba L.)

A study was made of the changes during development in the totalamino acid and 3, 4 dihydroxyphenylalanine (DOPA) content ofbean pod phloem sap, employing EDTA to aid phloem exudation.Two field bean lines, Dacre B and D, selected for their lowand high seed protein content respectively, were compared. Throughoutdevelopment, the sap samples of Dacre D had a greater aminoacid concentration than those from Dacre B. The sap of DacreB contained a higher proportion of DOPA than that of Dacre D.These two lines of Dacre were also studied with respect to accumulationof protein and uncombined amino acid in cotyledons grown bothin vitro and in vivo. Dacre D accumulated more total proteinthan Dacre B but contained a similar amount of uncombined aminoacids when grown in vivo. However, the amount of total proteinaccumulated was similar when the cotyledons were grown in vitro.The data suggest that the supply of nutrients to the pod maybe the basis of the different protein concentrations in themature seed of these lines. Vicia faba L., field bean, phloem sap, cotyledon culture, amino acids, DOPA, protein     

Effects of Nutrient Supply on Seed Growth of Field Bean (Vicia faba L.). 1. Effects of Different Sulphur and Methionine Regimes on Cotyledon Growth, Protein and Uncombined Amino Acids In vivo

The effects of exogenous methionine on growth of developingVicia faba seeds in vivo was studied. Methionine (51 or 102µmol in total) injected into the base of the pod overa period of 15 d (26–40 d after pollination) decreasedgrowth and protein accumulation in proximal seeds but increasedin distal seeds. Distal seeds of methionine injected pods accumulatedmore d. wt and protein than distal seeds of water-injected pods.However, on a pod basis methionine reduced overall seed growthand protein accumulation. Exogenous methionine caused a relative increase in legumin buta decrease in vicilin. Injected methionine also affected thecomposition of uncombined amino acids, especially those derivedfrom aspartic acid. In contrast, the amino acid compositionof the protein fraction did not change appreciably. The data suggest that seed growth is not limited by methioninebiosynthesis but seed protein composition is regulated by methionine. Vicia faba L., field bean, cotyledon, growth, in vitro culture, uncombined amino acids, protein composition, legumin, vicilin, methionine, sulphur     

Structural Characteristics and Fatty Acid Composition of Psophocarpus tetragonolobus Seeds

Winged bean (Psophocarpus tetragonolbtis) seed coat in the hilarregion consists of a double layer of sclereids, tracheid barand spongy parenchyma cells. This is contrasted to the seedcoat structure on either side of the hilar region, which hasa single layer of sclereids, columnar cells and crushed parenchymacells. Cotyledonary cells are large (50 to 100µm in diameter)and have cell walls 2·4 to 4·7 µm thickwith pit-pair structures. Protein bodies and lipid bodies arethe main structural components of the cytoplasm while only asmall number of starch granules are present in each cell. Themajor portion of the lipid can be removed by non-polar solventsand contains oleic and linoleic acids as the predominant unsaturatedfatty acids. High levels of behenic acid were present in both‘free’ and ‘bound’ lipids. Psophocarpus tetragonolobus (L.) DC., winged bean, seed structure, seed coat, protein bodies, lipid bodies, fatty acids, oleic acid, linoleic acid     

Characteristics of Sugar, Amino Acid and Phosphate Release from the Seed Coat of Developing Seeds of Vicia faba and Pisum sativum

After removal of the embryo from developing seeds of Vicia fabaL. and Pisum sativum L., the ‘empty’ ovules werefilled with a standard solution (pH 5.5). Seed coat exudatesof both species were collected during relatively long experiments(up to about 12 h) and the concentration of sugar (mainly sucrose),amino acids and phosphate in the exudate measured. A discussionis presented on the amino acid/sugar ratio and the phosphate/sugarratio in the seed coat exudate. A pretreatment (15 min) withp-chloromercuribenzenesulphonic acid (PCMBS) reduced the releaseof sugar, amino acids and phosphate from broad bean seed coats.After excision of ‘empty’ ovules of Vicia faba andPisum sativum from the maternal plant, 2–4 h after thistreatment a strong difference became visible between sucroserelease from excised seed coats and sucrose release from attachedseed coats. Similarly, when the rate of phloem transport ofsucrose into an ‘empty’ ovule of Vicia faba or Pisumsativum was reduced by a sub-optimal mannitol concentrationin the solution, a reduced rate of sugar release from the seedcoat could be observed. Excision and treatment with a sub-optimalmannitol concentration reduced the release of amino acids toa lesser extent than for sucrose. These treatments did not reducethe rate of phosphate release from the seed coat. Key words: Seed development, Seed coat exudate, Phloem transport     

Deoxyribonucleic Acid, Ribonucleic Acid, Protein and Uncombined Amino Acid Content of Legume Seeds During Embryogeny

The nucleic acid, protein and uncombined amino acid contentof seeds of soya-bean (Glycine max L. Merr.), garden pea (Pisumsativum L.), kidney bean (Phaseolus vulgaris L.) and peanut(Arachis hypogaea L.) were measured at various times duringseed formation in an effort to understand why the soya-beanhas nearly twice as much protein as the other legume seeds.In all these species the concentration of deoxyribonucleic acid,ribonucleic acid and uncombined amino acids decreased duringseed formation. The protein level of kidney bean was relativelyconstant during development whereas the protein levels of pea,peanut and soya-bean increased during development. The proteincontent of the soya-bean increased throughout development whereasthe protein increase in peanut took place early and that inpea took place later in development. The ratio of protein toribonucleic acid was highest in peanut, less in soya-bean, andlowest in pea and kidney bean. Similarly, the ratio of proteinto deoxyribonucleic acid was higher in kidney bean than in soya-bean.Soya-beans had a lower amino acid content than any of the otherseeds at all stages of development. These results indicate thatneither total deoxyribonucleic acid, ribonucleic acid nor uncombinedamino acid content is responsible for the higher protein contentof soya-beans.     

Occurrence of Multiple Forms of {alpha}-Amylase and Absence of Starch Phosphorylase in Soya Bean Seeds

Soya bean cultivars ‘Altona’ and ‘Chestnut’have active but quite low levels of -amylase. Activity was assayedwith specific substrates, oxidized amylose and ß-limitdextrin, which were resistant to attack by ß-amylase.During seed development -amylase activity increased to a maximumin both cultivars and then declined towards maturity. Matureand germinating seeds retain low activities of -amylase. Gelelectrophoresis separated the -amylase activity into six majorbands which occurred in both cultivars. The isozyme patternwas quite similar for developing, mature and germinating seed.although the relative proportion of activity in the variousbands changed somewhat. Starch phosphorylase was not detectedin any soya bean seed samples tested, but good activity wasfound in potato tuber extracts used as a control. Mixing experimentsusing soya bean and potato extracts indicated there were noinhibiting factors in soya bean seed extracts. Soya bean seedextracts probably do not contain starch phosphorylase. Glycine max (L.), Merr, soya bean, -amylase, isozymes, phosphorylase     

Effects of Nutrient Supply on Seed Growth of Field Bean (Vicia faba L.). 1. Effects of Different Sulphur and Methionine Regimes on Cotyledon Growth, Protein and Uncombined Amino Acids In vitro

The effects of differemt S and methionine regimes on growthof developing Vicia faba cotyledons in vitro were studied. Basalmedium (containing adequate S) supplemented with 05 mM methioninemarginally increased d. wt and uncombined amino acid accumulationbut adding 1–5 mM methionine inhibited both growth andprotein accumulation. Sulphur deficiency reduced both d. wtand protein accumulation but incresed accumulation of uncombinedamino acids. Adding 1 mM methionine to the S-deficient mediumrestored growth, normal protein and uncombined amino acid acnunulation.High sulphate medium (7.5 mM ) decreased d. wt, protein anduncombined amino acid accumulation. High sulphate medium or basal medium+methionine (05 mM) changedthe proportions of the seed proteins; legumin increased butvicilin decreased. Sulphur deficiency caused a relative increasein vicilin but a decrease in legumin. The different S and methionineregimes markedly changed the composition of the uncombined aminoacids, especially those derived from aspartic acid but not thecomposition of the protein fraction, except during S deficiency. The data presented indicates a flexibility in the storage proteincomposition of developing cotyledons grown in vitro, with theS and methionine status having a regulatory effect. Vicia faba L., field bean, cotyledon, growth, in vitro culture, uncombined amino acids, protein composition, legumin, vicilin, methionine, sulphur     

Changes in carbohydrates,amino acids and proteins in developing seed of chickpea

Developing seeds of chickpea cultivars G-130, L-550 and 850-3/27 grown under field conditions were sampled at different stages of maturity and analysed for soluble sugars, starch, soluble nitrogen, protein nitrogen and amino acids. Fr. wt of seeds of all three cultivars decreased after 28 days of flowering while the dry wt continued to increase. Rapid starch accumulation was observed between 14 and 28 days after flowering. Starch as per cent of seed dry wt started to decrease after 28 days, while starch per seed increased till maturity. The percentage of salt-soluble proteins decreased with maturation of seed. The electrophoretic pattern revealed that deposition of seed storage protein in cotyledons occurred 14 days after flowering. Most of the biochemical activity apparently occurred between 14 and 28 days after flowering.     

Effects of Inorganic Phosphate on the Utilization of Sucrose by Suspension-cultured Catharanthus roseus Cells

The metabolic fate of [U-¹⁴C]sucrose in suspension culturesof Catharanthus roseus cells was monitored for 96 h after thecells were transferred to fresh complete (‘+Pi’)or to phosphate-deficient Murashige and Skoog (‘–Pi’)medium. Sucrose was hydrolysed extracellularly to glucose andfructose. The rate of uptake of sugars by the cells was 1.5–3times higher in ‘+Pi’ culture than in ‘–Pi’culture. Little difference in the rate of incorporation of radioactivityinto the ethanol-soluble fraction was found between the ‘+Pi’and ‘– Pi’ cultures during the initial 24h of culture, but after 48 h the rate in ‘ +Pi’cultures was higher than that in ‘–Pi’ cultures.Incorporation of radioactivity into ethanol-insoluble macromoleculeswas always significantly higher in the cells in ‘+Pi’cultures than in those in ‘–Pi’ cultures.The results suggest that Pi strongly affects the utilizationof sugars by cultured plant cells through the stimulation oftransport of sugars as well as through the activation of metabolism. Catharanthus roseus, Madagascar periwinkle, suspension culture, inorganic phosphate, sucrose, transport, metabolism     

Effect of Source of Nitrogen on the Growth of Fiskeby Soya Bean: the Carbon Economy of Whole Plants

Fiskeby V soya bean was grown from seed germination to seedmaturation with two contrasting patterns of nitrogen metabolism:either wholly dependent on dinitrogen fixation, or with an abundantsupply of nitrate nitrogen, but lacking root nodules. The carbonand nitrogen economies of the plants were assessed at frequentintervals by measurements of photosynthesis, shoot and rootrespiration, and organic and inorganic nitrogen contents. Plantsfixing atmospheric nitrogen assimilated only 25–30 percent as much nitrogen as equivalent plants given nitrate nitrogen:c. 40 per cent of the nitrogen of ‘nitrate’ plantswas assimilated after dinitrogen fixation had ceased in ‘nodulated’plants. The rates of photosynthesis and respiration of the shootsof soya bean were not markedly affected by source of nitrogen;in contrast, the roots of ‘nodulated’ plants respiredtwice as rapidly during intense dinitrogen fixation as thoseof ‘nitrate’ plants. The magnitude of this respiratoryburden was calculated to increase the daily whole-plant respiratory loss of assimilate by 10–15 per cent over thatof plants receiving abundant nitrate. It is concluded that ‘nodulated’plants grew more slowly than ‘nitrate’ plants inthese experiments for at least two reasons: firstly, the symbioticassociation fixed insufficient nitrogen for optimum growth and,secondly, the assimila tion of the nitrogen which was fixedin the root nodules was more energy-demanding in terms of assimilatethan that of plants which assimilated nitrogen by reducing nitratein their leaves.     

Comparisons of Earlier- and Later-formed Pods of Chickpeas (Cicer arietinum L.)

In chickpeas (Cicer arietinum L.) flowering and pod developmentproceed acropetally. In plants grown under normal field conditionsat Hyderabad, in peninsular India, and at Hissar in north India,at successively apical nodes of the branches there was a declinein pod number per node, weight per pod, seed number per podand/or weight per seed. The percentage of nitrogen in the seedswas the same in earlier and later-formed pods at Hyderabad;at Hissar the later-formed seeds contained a higher percentage.Earlier- and later-formed flowers contained similar numbersof ovules. The decline in seed number and/or weight per seedin the later-formed pods of 28 out of 29 cultivars indicatedthat pod-filling was limited by the supply of assimilates orother nutrients. By contrast, in one exceptionally small-seededcultivar there was no decline in the number or weight of seedsin later-formed pods, indicating that yield was limited by ‘sink’size. Cicer arietinum L., chickpea, flowering, pod development, seed number, seed weight, nitrogen content     

Source-sink Relationships, Seed Sucrose Levels and Seed Growth Rates in Soybean

Field experiments using two soybean (Glycine max L. Merrill)cultivars (‘Elgin 87’ and ‘Essex’) wereconducted for 2 years near Lexington, KY, USA to evaluate theeffect of source-sink alterations on seed carbohydrate statusand growth. Sucrose concentrations in developing cotyledonsof control plants were consistently low (<50 m M) early inseed development, but they increased to 100–150 m M byphysiological maturity. The concentrations increased in bothyears by 47 to 59% when 90% of the pods were removed from ‘Elgin87’, but the increase had no effect on individual seedgrowth rate (SGR). Shading (80%) reduced cotyledon sucrose levelsand SGR in both years. The critical cotyledon sucrose concentration(the concentration providing 80% of the maximum cotyledon growthrate) was estimated fromin vitro cotyledon growth at sucroseconcentrations of 0–200 m M. These critical concentrationsvaried from 72–124 m M;in planta control cotyledon sucroseconcentrations were below this critical level during the firsthalf of seed growth but exceeded it in the later stages of growthin all experiments. The estimated critical concentration wasconsistent with the failure of in planta SGR to respond to anincrease in assimilate supply and with the reduction in SGRassociated with a decrease in assimilate supply. The resultssuggest that soybean SGR is generally sink limited if photosynthesisincreases during seed filling, but source limited if photosynthesisis reduced. Copyright 2001 Annals of Botany Company Glycine max(L.) Merrill, soybean, source-sink ratios, sucrose, starch, depodding, shade, in vitro culture     

Changes of Carbohydrates in Pepper (Capsicum annuum L.) Flowers in Relation to Their Abscission Under Different Shading Regimes

Abscission of pepper flowers is enhanced under conditions oflow light and high temperature. Our study shows that pepperflowers accumulate assimilates, particularly in the ovary, duringthe day time, and accumulate starch, which is then metabolizedin the subsequent dark period. With the exception of the petals,the ovary contains the highest total amounts of sugars and starch,compared with other flower parts and contains the highest totalactivity, as well as activity calculated on fresh mass basis,of sucrose synthase, in accordance with the role of this enzymein starch biosynthesis. Low light intensity or leaf removaldecreased sugar accumulation in the flower and subsequentlycaused flower abscission. The threshold of light intensity fordaily sugar accumulation in the sink leaves was much lower thanin flowers, resulting in higher daytime accumulation of sugarsin the sink leaves than in the adjacent flower buds under anylight intensity, suggesting a competition for assimilates betweenthese organs. Flowers of bell pepper cv. ‘Maor’and ‘899’ (sensitive to abscission) accumulatedless soluble sugars and starch under shade than the flowersof bell pepper cv. ‘Mazurka’ and of paprika cv.‘Lehava’ (less sensitive). The results suggest thatthe flower capacity to accumulate sugars and starch during theday is an important factor in determining flower retention andfruit set. Pepper; Capsicum annuum L.; abscission; shading; pepper flowers; ovary; leaves; sugars; starch; acid invertase; sucrose synthase     

Turnover of Storage Protein in Seeds of Soya Bean and Pea

We were interested in determining whether the low protein contentof pea seeds (Pisum sativum L.) as compared to soya bean seeds(Glycine max L. Merrill) might be due to faster degradationof the pea storage proteins during development of the seed.Pea and soya bean cotyledons were subjected to a ‘pulse-chase’experiment using [³H]glycine in in-vitro cultures. In peas,legumin had a half-life of 146 days, while vicilin had a half-lifeof 39 days. There was no measureable degradation of soya beanstorage proteins. Even with the pea storage proteins, the half-liveswere so much longer than the maturation time of seeds that degradationof storage proteins could not account for the lower proteincontent of peas as compared to soya beans. The validity of theseresults was indicated by the finding that non-storage proteinshad much shorter half-lives and that omission of a carbon ora nitrogen source greatly accelerated degradation. Labelledglycine was found to be a good probe for protein turnover studiesbecause it was very rapidly metabolized. Glycine max L. Merrill, soya bean, Pisum sativum, L. pea, protein turnover, storage proteins, legumin, vicilin     

Root exudates of plants

Summary Comparisons have been made of the amount and composition of seed and seedling exudates in barley, wheat, cucumber, and bean. Except in the case of wheat a greater proportion of the total nitrogen content in the seed exudates was formed by protein and peptide nitrogen than by nitrogen of free amino acids. In contrast, the greater part of the total nitrogen in the exudates of seedlings was formed by free amino acid nitrogen, except in the case of barley. Peptides represented 8 to 26 per cent of the protein and peptide fraction in seed exudates, the highest amount being found in bean. On an equal weight basis, the spectrum of amino acids released from seeds and seedlings differed little between barley, wheat and cucumber; greater differences were observed in bean exudates. Seedlings exuded reducing substances to a considerably greater extent than seeds. The spectrum of reducing sugars in seed and root exudates differed greatly, especially in the case of keto sugars. Differences in the organic acid spectra were small, except for bean plants, the seedling exudate of which contained more organic acids with a richer spectrum than seed exudate. Both seeds and seedlings of cucumber exuded a small quantity and a poor spectrum of organic acids.     

Relation between Nitrogen Status, Carbohydrate Distribution and Subsequent Rooting of Chrysanthemum Cuttings as Affected by Pre-harvest Nitrogen Supply and Cold-storage

This study investigated the relationship between internal nitrogenand carbohydrate distribution in chrysanthemum cuttings of twocultivars (‘Puma’, ‘Cassa’) when affectedby nitrogen supply to stock plants (0.6, 1.5, or 4.0 g N m^-2week^-1)and different periods (2, 3, or 4 weeks) of dark cold-storage(0.5 or 5°C), and adventitious rooting. Concentrations oftotal nitrogen (N_t) and nitrate in cuttings and the levels ofsugars, starch and fructan in different cutting parts (leaves,upper stem, and basal stem) were studied in relation to subsequentadventitious rooting at natural radiation in a greenhouse. Increasingnitrogen supply resulted in substantially lower starch levelsand higher sucrose concentrations in leaves when cuttings wereexcised. Fructan concentrations were low and decreased withincreasing nitrogen levels. Starch completely disappeared fromleaves and to a large extent from stems within the shorteststorage period. A less pronounced decrease in sugar concentrationwas observed, particularly in low-nitrogen cuttings and thecuttings of ‘Puma’. The number and length of adventitiousroots subsequently formed by unstored and stored cuttings waspositively correlated with initial N_t, and to a lesser extentwith initial nitrate concentrations in cuttings. Whereas rootingwas not limited by pre-rooting concentrations of carbohydratesin the different cutting parts, the generally higher rootingcapability of nitrogen-rich cuttings, a stronger nitrogen responseof ‘Cassa’, and increased rooting at a particularharvest date, were associated with higher sucrose:starch ratiosin leaves at harvest. This reflected an increased assimilateexport. By using this characteristic in a linear regressionmodel, total variability of root numbers, ranging from three–35per cutting, could be predicted to 57% for the unstored andto 40% for all cuttings. Increased basipetal transport of carbohydrates,of nitrogen compounds, and of auxins may be causally involvedin these associations. Copyright 2000 Annals of Botany Company Adventitious rooting, nitrogen, sugars, carbohydrates, source-sink, partitioning, quality, storage, cuttings, stock plants, chrysanthemum, Dendranthema grandiflorum     

Starch Metabolism in Developing and Germinating Soya Bean Seeds is Independent of {beta}-Amylase Activity

Developing seeds of soya bean cultivars Chestnut and Altonahave only trace amounts of ß-amylase activity. Comparedto a standard variety, Wells, ß-amylase activitieswere 200–300 times lower in Chestnut and Altona. Nevertheless,Chestnut and Altona accumulate starch as a transient reservematerial which is utilized later in development. Seeds of Chestnutand Altona also produce starch early in germination which subsequentlydeclines after the 4th day of germination. Throughout germinationß-amylase levels in these cultivars are about 300-foldlower than that observed in Wells, which has a similar patternof starch metabolism. Widely varying levels of ß-amylasein both developing and germinating seeds appear to be unrelatedto starch metabolism which is very similar in all cultivarsstudied. Consequently, ß-amylase activity seems irrelevantto starch metabolism in the soya bean seed. starch, ß-amylase, Glycine max. (L.), Merr, soya bean     

Protein Bodies of Developing Seeds of Vicia faba

Changes in fine structure and starch, nitrogen, and solublesugar content were followed through to maturation in developingcotyledons of Vicia faba. Various ultrastructural changes wereobserved in the developing cotyledons, notably an increase inthe number of membrane-bound ribosomes which corresponded withthe onset of storage protein deposition. The build-up of storageprotein was shown to occur in the cytoplasm within membrane-boundvacuoles which subsequently became the protein bodies of themature seed, retaining the original tonoplast as the boundingmembrane of the protein body. Nuclei became lobed during thelater phases of maturation; phytoferritin was observed in plastidsof mature seeds. The deposition of reserves in the cotyledonswas complete by 85–90 days after flowering, followingwhich water was lost until the seed became hard and ‘ripe’by no days after flowering.     

Predator-prey interactions between Isochrysis galbana and Oxyrrhis marina. II. Release of non-protein amines and faeces during predation of Isochrysis

During the growth of Isochrysis galbana, several non-proteinamines may be detected in the growth medium. Of these, one (termed‘TTl’) accumulates in proportion to the numbersof cells present. The concentrations of ‘TTl’, andof another (termed ‘TA’), are 3–5 times higherin cultures in which Isochrysis is predated by Oxyrrhis marina.The lowest estimates of the concentration of extracellular ‘TTl’are an order of magnitude higher than those of any protein aminoacid. Of the protein amino acids, some like glycine are utilizedduring predation while others, like histidine, accumulate inthe medium Because of the unknown N-content and reactivity ofthe non-protein amines during HPLC, it is not possible to sayif these compounds (together with other components of dissolvedorganic N) form a significant proportion of the unaccountedfor N in the system after predatory activity. During predationin the absence of detectable free ammonium (when Isochrysismay be expected to be N-deprived), particles accumulate in themedium. Most of these are <2.5 µ.m in diameter andare suggested to be remains of digested prey. There is evidenceof a reassimilation of these particles by prey-deplete Oxyrrhis.     

The Developmental Anatomy of the Root System in Yam Bean, Pachyrhizus erosus Urban

Investigations revealed that the anatomy of the primary radicularroot of yam bean (Pachyrhizus erosus L.) was typically dicotyledonousexcept that the xylem was not completely developed centripetally.Most of the roots had tetrarch xylem, although a few triarchand pentarch roots were also observed. In both tuberous andnon-tuberous roots, secondary thickening occurred by the formationof the meristematic vascular cambium which formed secondarytissues in a normal fashion. Subsequently, tuberization wasinitiated in the secondary xylem by the development of anomalous‘secondary’ cambia from parenchyma cells surroundingvessel elements. Anomalous ‘secondary’ cambia alsodeveloped from parenchyma cells not associated with vessels.Subsequently, anomalous ‘tertiary’ cambia differentiatedfrom tissues produced by the anomalous ‘secondary’cambia. Activities of these anomalous cambia resulted in theproduction of parenchyma storage cells and were chiefly responsiblefor the growth of the mature tuber. Pachyrhizus erosus L., yam bean, tuberous root, anatomy, anomalous ‘secondary’ cambia, anomalous ‘tertiary’ cambia, centripetal xylem development