Magnesium uptake by soybeans

Magnesium contents of soybean (Glycine max) roots increase and the K and Ca contents decrease with increased MgCl₂ concentrations in ambient solutions. The Mg uptake is inhibited when both Ca and K are present in the solution, but not by K or Ca alone. Chloride uptake, which is very low from the MgCl₂ solution, is greatly enhanced by the presence of K. The selectivity against Mg imparted by K + Ca appears to be at an external barrier for cation uptake as shown by its dependence on the presence of Ca in the external solution. The Ca content of roots is influenced only slightly by changes in external Ca concentrations from 10⁻⁴ to 10⁻²m, but that of shoots is greatly enhanced as the Ca concentration is increased or the K concentration is decreased. These effects on Ca contents are explained as arising from transport to the shoot without involvement of vacuoles of root cells.     

Taxonomy of the genusGlycine,domestication and uses of soybeans

The genusGlycine has had a stormy taxonomic history. Recent studies of herbarium specimens and cytological and morphological analyses of living collections, coupled with chemotaxonomic investigations, have made it necessary to revise the genus. In the first part of this paper the current taxonomic status of the genusGlycine is reviewed. The soybean was domesticated in China. It is unfortunate that the literature concerned with the antiquity and historical development of the soybean is obscured by legends and myths. In the second section of the paper, the archeological, historical, agricultural and botanical literature is summarized in order to present all the known evidence as to when, where and by whom the soybean was domesticated. The soybean is the world’s premier source of dietary vegetable oil and is nutritionally an excellent and inexpensive source of protein for use either as human food or animal feed. In addition, the soybean has numerous industrial uses. In the last section of this paper the traditional uses of fermented and nonfermented soybeans in the East as well as the high-technology-developed uses of soybeans in the West are summarized.     

The digestibility of raw and processed soybeans by Helmeted Guineafowl,Numida meleagris

Helmeted Guineafowl, Numida meleagris, populations have declined significantly within the Midlands of KwaZulu-Natal since the early 1980s. Because guineafowl have been observed feeding on harvested soybean lands and because raw soybeans are known to contain anti-nutritional factors, research into the digestibility of raw soybeans was conducted to investigate possible localized factors in suppressing populations of these birds. A digestibility study was carried out on the apparent metabolizable energy (AME) and the amino acids of both raw and processed soybeans, as well as a number of other feed ingredients, using Helmeted Guineafowl and adult roosters, Gallus gallus, as a control. The results of the energy balance studies were similar for both the guineafowl and the roosters. Soybean, both raw and processed, was found to be comparable with the other feed ingredients in terms of the digestibility of gross energy, but the amino acid digestibility of raw soybeans was considerably lower than that of processed soybean oilcake meal. The availability of raw soybean may thus only be contributing to localized dietary constraints within guineafowl populations.     

The inactivation of lipoxygenase-1 from soybeans by amidrazones

Several compounds containing an amidrazone moiety are known to be potent inhibitors of lipoxygenase-1 activity from soybeans (L-1) with IC(50)-values in the range of 10 microM to 38 nM. Recently it was proposed that phenylhydrazones act as irreversible mechanism-based inhibitors of lipoxygenases. Because of the structural similarities between both compounds it was assumed for the amidrazones to affect the lipoxygenase reaction in the same suicide manner. Cyclisation of the amidrazone moiety to the corresponding triazoline should yield compounds without substrate properties. However, they are still able to inactivate the enzyme. The inhibition of L-1 from soybeans by two representative compounds of a series of amidrazones and triazolines has been characterised as a slow, tight-binding interaction via a two-step mechanism. Dialysis experiments indicate the reversible nature of interaction of the amidrazone with the ferrous enzyme while the ferric enzyme was irreversibly inactivated. In contrast, the interaction of the triazoline with both the ferric and ferrous species of the enzyme was completely reversible which demonstrates the noncovalent and reversible mode of binding and inactivation. The triazoline was found not to be a substrate of the dioxygenase reaction of lipoxygenase whereas the amidrazone is only a very poor substrate of the enzymatic oxidation reaction. The presented results point out the inhibition of L-1 by amidrazones and triazolines to fall into the same kinetic classification. Therefore it is obvious that the inhibition of L-1 by these compounds cannot be attributed to a truly mechanism-based inactivation.     

Endophytic colonisation of tobacco,corn, wheat and soybeans by the fungal entomopathogen Beauveria bassiana (Ascomycota,Hypocreales)

We demonstrate the effectiveness of three inoculation methods (foliar spray, seed immersion and root immersion) in establishing fungal the entomopathogen Beauveria bassiana as an endophyte in tobacco, corn, wheat and soybean. Colonisation of leaves by B. bassiana was assessed 7, 14, 21 and 28 days post-inoculation. There were significant differences (p < 0.001) in endophytic colonisation among the different inoculation techniques.     

Obligatory reduction of ferric chelates in iron uptake by soybeans

The contrasting Fe²⁺ and Fe³⁺ chelating properties of the synthetic chelators ethylenediaminedi (o-hydroxyphenylacetate) (EDDHA) and 4,7-di(4-phenylsulfonate)-1, 10-phenanthroline (bathophenanthrolinedisulfonate) (BPDS) were used to determine the valence form of Fe absorbed by soybean roots supplied with Fe³⁺-chelates. EDDHA binds Fe³⁺ strongly, but Fe²⁺ weakly; BPDS binds Fe²⁺ strongly but Fe³⁺ weakly. Addition of an excess of BPDS to nutrient solutions containing Fe³⁺-chelates inhibited soybean Fe uptake-translocation by 99+%; [Fe(II) (BPDS)₃]⁴⁻ accumulated in the nutrient solution. The addition of EDDHA caused little or no inhibition. These results were observed with topped and intact soybeans. Thus, separation and absorption of Fe from Fe³⁺-chelates appear to require reduction of Fe³⁺-chelate to Fe²⁺-chelate at the root, with Fe²⁺ being the principal form of Fe absorbed by soybean.     

Bacillus fermentation of soybeans

Kinema fermentations of Indian and Canadian No. 1 soybeans by Bacillus sp. DK-W1 and by mixed cultures of Bacillus sp. DK-W1 and Enterococcus faecium DK-C1 were essentially identical. The viable cell count of Bacillus increased from an initial 10⁵ to 10¹⁰ c.f.u./g wet wt after 48 h incubation at 37°C. The pH of the fermentation dropped from an initial 6.9 to about 6.4 after 8 h and then rose to 8.6 after 32 h, with a coincident increase in proteolytic activity and ammonia concentration. The fermentations containing E. faecium and Bacillus exhibited a greater initial pH decline and a slightly retarded subseqent increase in pH compared with fermentations with Bacillus only. The presence of E. faecium had no detectable effects on growth of the Bacillus, proteolytic activity, ammonia production or the final pH of the fermentations.P.K. Sarkar was and P.E. Cook and J.D. Owens are with the Food Microbial Interactions Laboratory, Department of Food Science and Technology, University of Reading, Reading RG6 2AP, UK; P.K. Sarkar is now with the Microbiology Laboratory, Centre for Life Sciences, University of North Bengal, Siliguri 734430, India.     

Solubilization conditions for hydrophobic membrane protein,oleosin, in soybeans

Oleosins are amphipathic proteins found in soybeans that give stability to oil-bodies by surrounding them. Furthermore, oleosins have broad biotechnological applications in protein purification and in immobilization as a tagging parther. In this study we provide the proper combinations of detergents and chaotropes for solubilization of oleosins. The solubilization effects of each detergent were compared by the results of SDS-PAGE analysis, from the density measurement of each band using an image analysis program. Among the twelve chemicals tested, 3-(decyldimethylammonio) propanesulfonale inner salt (SB 3–10), nonaethylene glycol octylphenyl ether (NP-40), and n-dodecyl-β-d-maltoside (DM) were determined to be effective for oleosin solubilization. In addition, urea, thiourea, and reducing agents played roles in enhancing the effects of the detergents. The best results were obtained with 2.5% of each detergent in combination with 4 M urea and 2 M thiourea at room temperature. The zwitterionic detergent, SB 3–10, is recommended as the best non-denaturant for the solubilization of soybean oleosins with the advantage of its easy removal by dialysis due to its low molecular weight and a high critical micelle concentration.     

Composition of seed storage proteins changed by glutathione treatment of soybeans

The application of glutathione to immature soybean cotyledons reduced the accumulation of the beta subunit of beta-conglycinin, and increased the accumulation of most glycinins. Both reduced and oxidized forms of glutathione had these effects. The application of an inhibitor of glutathione synthesis, buthionine sulfoximine, increased accumulation of beta subunit. These results suggest that glutathione is important in affecting the composition of seed storage proteins.     

Chloroplast ultrastructure, chlorophyll fluorescence, and pigment composition in chilling-stressed soybeans

Shoots of 16-day-old soybeans (Glycine max L. Merr. cv Ransom) were chilled to 10°C for 7 days and monitored for visible signs of damage, ultrastructural changes, perturbations in fluorescence of chlorophyll (Chl), and quantitative changes in Chl a and b and associated pigments. Precautions were taken to prevent the confounding effects of water stress. A technique for the separation of lutein and zeaxanthin was developed utilizing a step gradient with the high performance liquid chromatograph. Visible losses in Chl were detectable within the first day of chilling, and regreening did not occur until the shoots were returned to 25°C. Ultrastructurally, unstacking of chloroplast grana occurred, and the envelope membranes developed protrusions. Furthermore, the lipids were altered to the point that the membranes were poorly stabilized by a glutaraldehyde/osmium double-fixation procedure. Chl fluorescence rates were greatly reduced within 2 hours after chilling began and returned to normal only after rewarming. The rapid loss of Chl that occurred during chilling was accompanied by the appearance of zeaxanthin and a decline in violaxanthin. Apparently a zeaxanthin-violaxanthin epoxidation/de-epoxidation cycle was operating. When only the roots were chilled, no substantial changes were detected in ultrastructure, fluorescence rates, or pigment levels.