Developing Soybean Seeds Research Articles

Ontogeny of Lipid Bodies in Developing Soybean Seeds1

Cells of developing soybean, cultivar ‘Wells’ (Glycine max (L.) Merr.), cotyledons contained plastids and lipid bodies at the earliest stage investigated, 15 days after flowering. Lipid bodies seemed to arise directly in the cytoplasm and their proximity to plastids maybe coincidental. By 34 days after flowering lipid bodies increased dramatically accompanied by a massive proliferation of rough endoplasmic reticulum. In some instances this rough endoplasmic reticulum was closely associated with lipid bodies but in other cases there was no close association. In maturing seeds, plastids were frequently seen to contain lipid bodies which may indicate a loss of plastid integrity. Mature seeds contained numerous discrete lipid bodies which stained uniformly and had a half‐unit membrane border. A possible route for lipid body ontogeny consistent with the ultrastructural observation is that fatty acids are just synthesized in the plastids. Possibly then the fatty acids are transported and assembled into triglyceride molecules by the rough endoplasmic reticulum and released into the cytoplasm. Also the proteinaceous material associated with the lipid body membrane probably originate from the endoplasmic reticulum.

An In Vivo Technique for the Study of Phloem Unloading in Seed Coats of Developing Soybean Seeds

A technique has been developed which permits mechanistic studies of phloem unloading in developing seeds of soybean (Glycine max cv Clark) and other legumes. An opening is cut in the pod wall and the embryo surgically removed from the seedcoat without diminishing the capacity of that tissue for assimilate import, phloem unloading, or efflux. The sites of phloem unloading were accessible via the seedcoat apoplast and were challenged with inhibitors, solutes, buffers, etc., to characterize the unloading process.Unloading is stimulated by divalent metal chelators and diethylstilbestrol, and inhibited by metabolic uncouplers and sulfhydryl group modifiers. Solutes released from the seed coat had a carbon/nitrogen ratio of 31 milligrams carbon per milligram nitrogen; sucrose represented 90% of the carbon present and various nitrogenous solutes contributed the remaining 10%. Unloading could be maintained for up 8 hours at rates of 0.5 to 1.0 micromoles per hour, providing a valid, convenient in vivo technique for studies of phloem unloading and seed growth mechanisms.

Use of [3,4-<sup>14</sup>C]Glucose to Assess in vivo Competition for Phosphoenolpyruvate Between Phosphoenolpyruvate Carboxylase and Pyruvate Kinase in Developing Soybean Seeds

Use of [3,4-<sup>14</sup>C]Glucose to Assess in vivo Competition for Phosphoenolpyruvate Between Phosphoenolpyruvate Carboxylase and Pyruvate Kinase in Developing Soybean Seeds

Temperature and Oxygen Effects on 14C-Photosynthate Unloading and Accumulation in Developing Soybean Seeds

The environmental sensitivity of the processes associated with the import of photosynthate by developing soybean seeds was investigated within intact fruit and with excised, immature embryos. Intact pods of field-grown (Glycine max [L.] Merr.) Amsoy 71 soybeans were subjected to localized regimes of 0, 21, or 100% O(2) and 15, 25, or 35 degrees C during pulsechase translocation experiments and, 2.5 hours later, the uptake and distribution of (14)C-photosynthate among dissected fruit tissues determined. In other experiments, excised embryos were incubated in [(14)C]sucrose solutions under various experimental conditions to separate the effects of these treatments on accumulation by the embryos from those which may operate on phloem unloading in the maternal seedcoat.Import of (14)C-photosynthate by intact soybean fruit was both temperature- and O(2)-dependent. This dependency was shown to occur only within the seeds; import by the pod walls was essentially insensitive to fruit temperature or O(2) treatments. The embryos of anaerobic fruit were completely unlabeled, regardless of fruit temperature. But under anaerobic in vitro incubation conditions, uptake of [(14)C]sucrose in excised embryos was only 30% less than that in aerobic in vitro conditions. The data suggest that, within intact fruit, anoxia prevented sucrose efflux from the seed coat phloem and any subsequent uptake by the embryo. The demonstrated energy dependence of phloem unloading may reflect requirements for membrane integrity or energy metabolism in the companion cell-sieve element complex, consistent with a facilitated unloading process.Collectively, these data characterize the environmental sensitivity of photosynthate import in developing soybean fruit. They imply that environmental regulation of import may occur at both the embryo level and at the phloem terminals within the seed coat.

Interactions of Phosphoenolpyruvate Carboxylase and Pyruvic Kinase in Developing Soybean Seeds

Interactions of Phosphoenolpyruvate Carboxylase and Pyruvic Kinase in Developing Soybean Seeds

Adenylate and Nicotinamide Nucleotides in Developing Soybean Seeds During Seed-Fill

Profiles of adenylate and nicotinamide nucleotides in soybean seeds were determined during seed-fill. The ATP content per seed increased during the early seed-filling stages to a level of 10 to 12 micrograms per seed. Seed ATP decreased after 40 days of development and reached its lowest level of less than 1 microgram at maturity. The ATP:ADP ratios were relatively constant at all seed development stages. Sharp increases in AMP levels during the late seed-fill stages were paralleled with a disappearance of ATP and ADP pools resulting in a reduced seed energy charge. Energy charge varied from the highest value of 0.78 at mid-seed-fill to less than 0.10 at maturity.Of the oxidized (NAD, NADP) and reduced (NADH, NADPH) nicotinamide nucleotide forms, NAD was the most abundant. Levels as high as 17.5 micrograms per seed were observed during the mid-seed-filling stages. NADP was found almost exclusively in the reduced form with a NADP: NADPH ratio of less than 0.35, whereas the reverse was noted for NAD which was found mainly in the oxidized form with a NAD:NADH ratio in the range of 5 to 25. NADP was detected in low concentrations compared to the other adenylate and nicotinamide nucleotides. The nicotinamide redox charge defined as (NADH + NADPH)/(NAD + NADH) + (NADP + NADPH) was calculated to express the state of the energy balance between the oxidized and reduced nicotinamide nucleotide forms. The nicotinamide redox charge varied between 0.15 and 0.30 during seed development and was significantly lower than that found for the adenylate energy charge.

β-Conglycinins in Developing Soybean Seeds

The temporal sequence of development of the major proteins of seeds of soybean (Merr.) has been studied during development of cotyledons from flowering to maturity. A well-defined difference occurred in the times of appearance and the periods of maximum accumulation of alpha, alpha'-, and beta-subunits of betaconglycinin. Whereas alpha- and alpha'-subunits appeared 15 to 17 days after flowering, accumulation of beta-subunit did not commence until 22 days after flowering. Such alterations in subunit composition infer that changes also occurred in the amino acid composition of betaconglycinin during maturation, particularly in the content of methionine which is low in the beta-subunit.

Components of Developing Soybean Seeds: Oil, Protein, Sugars, Starch, Organic Acids, and Amino Acids1

AbstractA thorough chemical analysis on the composition of developing soybean [Glycine max (L.) Merr.] seeds does not appear in the literature. Several investigators have determined protein and oil, while others have determined the carbohydrates. The purpose of this study was to make a thorough analysis of the developing soybean seed, including protein, oil, sugars, starch, organic acids, and amino acids. Soybean seeds from ‘Harosoy 63’ grown in the field and ‘Steele’ grown in the greenhouse were analyzed for these components from 10 days after flowering, at 10‐day intervals, to maturity. These components accounted for 75% of the dry weight of the seed. The remaining dry weight of the seed is in cellulose, crude fiber, and ash. Oil and protein (mg/seed) increased until maturity in Harosoy 63 but leveled off before maturity in Steele. When oil and protein are expressed as percentage dry weight, similar patterns were observed for both cultivars. The sugars glucose, fructose, galactose, sucrose, raffinose, and stachyose were all detected in the soybean seed. Raffinose and stachyose were not detected until 50 and 40 days after flowering in Harosoy 63 and Steele, respectively. Starch reached a maximum value of 14.6 mg/seed in Harosoy 63 and 7.9 mg/seed in Steele at 40 and 30 days after flowering, respectively. Starch then declined sharply in both varieties. The water soluble polysaccharide (mg/seed) fraction showed a steady rise for both varieties throughout the study, but declined as percent of dry weight. The concentration of organic acids was low, with glycolic, succinic, malic, and citric being detected. Citric acid was detected in the greatest quantity. Seventeen amino acids and one unknown component were detected in the amino acid analysis. Of the amino acids detected, seven showed increases while three amino acids as well as the unknown showed decreases. Analysis of variances and standard error of the mean were performed on the data for each trait in each variety using a completely randomized design with specific tests for linear regression over the 70 or 60 days after flowering. In addition, quadratic regression was run for starch. Simple correlation coefficients were also found between all the traits studied and can be obtained upon request.

Phospholipids in the Developing Soybean Seed

The distribution of phospholipids in developing soybean seeds [Glycine max (L.) Merr., var. "Chippewa 64," "Harosoy 63," "Wayne," and "Clark 63"] was followed. From 30 to 60 days after flowering expressed as mole per cent of phospholipid phosphorus phosphatidic acid decreased from 14.8 to 9.1; phosphatidylinositol increased from 0 to 9.1; phosphatidylcholine increased from 8.2 to 9.8; phosphatidylethanolamine increased from 5.3 to 8.6; phosphatidylglycerol increased from 3.2 to 4.8; diphosphatidylglycerol increased from 2.7 to 4.1; and N-acylphosphatidylethanolamine decreased from 65.8 to 54.6. However, from 60 days after flowering to maturity, phosphatidic acid decreased to 0; phosphatidylinositol increased roughly 2-fold; phosphatidylcholine increased roughly 4.7-fold; phosphatidylethanolamine increased 3-fold; N-acylphosphatidylethanolamine decreased 11-fold; whereas phosphatidylglycerol and diphosphatidylglycerol remained essentially constant. Percentages of individual phospholipid species were not statistically different between any two varieties at a given time period.Immature soybean cotyledons incubated with (14)C-acetate or -pyruvate demonstrated rapid incorporation into the phospholipid fraction. N-acylphosphatidylethanolamine was found to account for nearly 70% of the total radioactivity incorporated by the total polar lipid fraction and greater than 30% of the total radioactivity added.

Protein, Oil, and Fatty Acid in Developing Soybean Seeds1

We followed the deposition of protein, oil and fatty acids in developing seeds of ‘Acme,’ ‘Chippewa,’ and ‘Harosoy 63’ soybeans [Glycine max (L.) Merrill] to gain a better insight to the accumulation of these components. Nonprotein N and protein N were estimated by micro‐Kjeldahl procedure. Oil was determined by NMR, while fatty acids were analyzed by gas liquid chromatography.At approximately 25 days after flowering the composition of the seeds was about 30% protein and 5% oil; however, this represents only 2% of the total protein and 1% of the oil in the mature seed.From 24 to 40 days after flowering, oil percentage increased rapidly to 20%, which represents 30% of the total oil in the mature seed. The percentage of palmitic, stearic, and linolenic acid in the oil decreased, while the percentage of oleic and linoleic acid increased during this period. Although the percent values of the fatty acids changed markedly, actual amounts of all fatty acids increased. Percent nonprotein N decreased slightly, while percent protein N showed a concommittant rise from 24 to 40 days after flowering.During the remainder of the deevlopment (about 25 days) of the soybean seed, percent values of the components remained essentially constant. During this time, however, 70% of the total protein, oil, palmitic acid, oleic acid, and linoleic acid were synthesized, and 65% of the total stearic acid and 50% of the total linolenic acid also were synthesized.

Changes in Individual Nucleotides of Developing Soybean Seeds

AbstractPerchloric acid extracts of soybean seeds were separated by column chromatography into 17 peaks. Thirteen nucleotides were identified in 11 of these peaks (NAD, CMP, CDP, CTP, AMP, ADP, ATP, GMP, GDP, GTP, UMP, UDP, and UTP). Two of the peaks were identified as ascorbic acid and dehydroascorhic acid. Four peaks remain unidentified although one of these appears to be protein.Monophosphates decreased and triphosphates increased as development proceeded. Diphosphates were initially low and showed no statistically significant difference with maturity.The accumulation of triphosphates in late stages of development is discussed in relation to synthetic activities of the developing seeds.

Measurement of Ribonucleic Acids and Total Free Nucleotides of Developing Soybean Seeds

Measurement of Ribonucleic Acids and Total Free Nucleotides of Developing Soybean Seeds