Soybean lines lacking the 120,000-dalton seed lectin.

Seeds of 102 lines of Glycine max (L.) Merr., the soybean, were screened quantitatively for the presence of the 120,000-dalton soybean lectin. Wide variation in the content of this lectin was noted, and five lines of soybean whose seed totally lacked the lectin were identified. Roots of all five lines were effectively nodulated by several strains of Rhizobium japonicum, thus indicating that the 120,000-dalton soybean seed lectin is probably not required for the initiation of soybean-Rhizobium symbiosis.

Genetics and breeding of soybeans lacking the Kunitz trypsin inhibitor.

The major trypsin inhibitor present in soybean [Glycine max (L.) Merrill] seed is the Kunitz trypsin inhibitor or soybean trypsin inhibitor A2 (SBTI-A2). Four forms of SBTI-A2 have been identified in the U.S. soybean germplasm collection. Three of the forms designated Ti(a), Ti(b), and Ti(c) are electrophoretically distinguishable from one another by their different Rf values of 0.79, 0.75, and 0.83, respectively. The three forms are inherited as codominant alleles in a multiple allelic series at a single locus. The fourth form which is the absence of SBTI-A2 is found in P.I. 157440 and P.I. 196168. The allele lacking SBTI-A2 is designated ti and is inherited as a simple recessive to the other three SBTI-A2 forms. Tia is the most common SBTI-A2 allele in the germplasm collection. Ti(b) primarily is found in Japan and Korea. Ti(c) is associated with the Tohoku District, Japan. P.I. 157440 and P.I. 196168 are from Korea. Linkage studies revealed that the Ti and Ap loci are linked by 16.2 +/- 1.5 map units. Three isolines of soybeans lacking the Kunitz trypsin inhibitor, derived by backcrossing P.I. 157440 to three commercial cultivars (Ti(a)Ti(a)), were released to the research community. Results of preliminary feeding trials, with chicks and young pigs, revealed that gain/feed was significantly higher in lines lacking the Kunitz trypsin inhibitor than cultivars containing the inhibitor. However, the gain/feed was lower in both feeds than commercially processed soybean meal.

Effect of heat on the nutritional quality and safety of soybean cultivars.

To evaluate whether soybean strains with reduced levels of trypsin inhibitors have enhanced nutritional and safety characteristics, we measured protease inhibitor content of a standard cultivar (Williams 82) and an isoline (L81-4590) lacking the Kunitz trypsin inhibitor, using enzyme inhibition assays and enzyme-linked immunosorbent assays (ELISA). Less heat was needed to inactivate the remaining trypsin inhibitory activity of the isoline than that of the standard soybean cultivar. In fact, autoclaving (steam heating at 121 degrees C) of the isoline for 20 min resulted in a near zero level of trypsin inhibitor activity, while 20% remained in the Williams 82 sample. Feeding studies with rats showed that the raw soy flour prepared from the isoline was nutritionally superior to the raw flour prepared from the standard variety, as measured by PER and pancreatic weights. Since the content of amino and fatty acids of the flours from both strains was identical and the hemagglutinating activities were within a factor of 2, the increased PER was likely due to the lower level of trypsin inhibitory activity in the isoline. Steam heating the flours for up to 30 min at 121 degrees C progressively increased the PER for both strains. Preliminary screening of several accessions from the USDA Soybean Germplasm Collection showed considerable variation in the content of trypsin inhibitors, sulfur amino acids, and lectins. The BBI content of these cultivars, determined by chymotrypsin inhibition assays, was identical to that found by ELISA. The results indicate that further screening studies could lead to the discovery of soybeans which yield flour that is safe and nutritious, with minimal need for heating.

Utilization by growing and finishing pigs of raw soybeans of low Kunitz trypsin inhibitor content.

Three trials were conducted to compare acceptance and utilization by growing and finishing pigs of diets containing supplemental protein from either heated, solvent-extracted soybean meal (SBM), raw low-Kunitz trypsin inhibitor soybean (LT) or raw commercially grown Williams cultivar soybean with high Kunitz trypsin inhibitor content (HT). In Trial 1, 36 crossbred pigs, averaging 7 kg in weight, were fed 1) corn-SBM, 2)corn-LT or 3) corn-HT diets for 28 d. Diets were formulated to be isolysinic and to have similar calorie:lysine ratios. Average daily gain and gain/feed were higher (P less than .01) for pigs fed the corn-SBM diet than for pigs fed the corn-LT diet; average daily gain and gain/feed were higher (P less than .01) for the corn-LT diet than for the corn-HT. Average daily feed intake did not differ (P greater than .05) among diets. In Trial 2, 48 crossbred pigs averaging 67 kg were fed diets similar to those in Trial 1 but with lower lysine values. The daily gain (.95 kg) of pigs fed the corn-SBM diet was greater (P less than .05) than for pigs fed the corn-LT diet (.87 kg), which in turn was greater (P less than .05) than for the pigs fed the corn-HT diet (.83 kg). Daily feed intake (kg) and gain/feed were 3.27 and .291, 2.97 and .293, and 3.07 and .270, respectively, for pigs fed the corn-SBM, corn-LT and corn-HT diets. In Trial 3, 18 castrate male pigs averaging 12.4 kg were fed cornstarch-based diets with either SBM, LT or HT as the source of protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of soybean variety and processing on growth performance of young chicks and pigs.

The objective of this study was to determine whether soybeans without the Kunitz trypsin inhibitor and lectins could be fed effectively to young chicks and pigs. Specifically, we compared the growth performance of chicks and pigs fed diets containing modified soybeans: Kunitz trypsin inhibitor-free (KF), lectin-free (LF), lectin and Kunitz trypsin inhibitor-free (LFKF), conventional soybeans (CSB), and commercially obtained, dehulled, solvent-extracted soybean meal (SBM). A 7-d chick experiment was conducted to evaluate the nutritional value of CSB, KF, LF, LFKF, and SBM. The experiment was conducted as a completely randomized design, with four replicates, five treatments, and six male chicks per pen (n = 120). The five treatments consisted of 23% CP dextrose-soybean-based diets containing KF, LF, LFKF, CSB, or SBM as the source of dietary protein. A 28-d pig experiment was conducted to evaluate the nutritional value of CSB, LF, LFKF, and SBM. Pens of four pigs were assigned randomly to a control, corn-SBM, or one of six corn-soybean diets containing raw or extruded soybean varieties as a 2 x 3 factorial arrangement of treatments in a randomized complete block design with five blocks per treatment (n = 140). Chicks fed diets containing any of the raw soybean varieties gained less weight (P < 0.05) than chicks fed SBM (22.81 g/d for SBM vs. 14.17 g/d for the raw soybeans combined). Among the raw soybean treatments, there was a greater effect on growth performance (P < 0.05) by removing both lectins and Kunitz trypsin inhibitor (ADG of 16.56 g for LFKF) than by removing each antinutritional factor separately (ADG of 14.38 and 14.11 g for KF and LF, respectively). Pig growth performance was different (P < 0.001) for SBM (ADG of 409 g) and all the varieties when extruded (ADG of 450 g for CSB, 417 g for LF, and 408 g for LFKF) compared with the raw soybean treatments (ADG of 101 g for CSB, 165 g for LF, and 266 g for LFKF). Among the raw soybean treatments, growth performance improved (P = 0.003) as the antinutritional factor, lectin, was removed from the soybean and improved further (P = 0.045) when both lectins and Kunitz trypsin inhibitor were removed. The growth-inhibiting effect of feeding modified soybeans to young animals was more detrimental for pigs than for chicks in our experiments. Soybeans without the Kunitz trypsin inhibitor and lectins cannot be fed successfully to young chicks and pigs without heating.

A Greenhouse Technique for Assessing Phytophthora Root Rot Resistance in Glycine max and G. soja.

New sources of soybean (Glycine max) resistance to Phytophthora sojae are needed to provide effective resistance because of the rapidly changing race patterns of P. sojae in fields. The objectives of our study were to develop a method to screen Glycine soja for resistance to P. sojae and then use this methodology to screen G. soja lines for resistance to P. sojae races 1, 3, and 20. An agar plug-inoculation method, in which a 3-mm-diameter mycelial plug of the fungus was placed mycelium side down on cotyledons of 10-day-old soybean seedlings, was directly compared with the traditional hypocotyl inoculation method. There was no significant difference between the hypocotyl- and plug-inoculation methods when tested on four soybean differential lines using three P. sojae races. The plug-inoculation method then was used to screen 430 G. soja accessions for resistance to P. sojae race 3. Nine G. soja accessions were retested with races 1, 3, and 20. Of the 430 G. soja accessions tested, 22 accessions had survival rates higher than 75% and nine had rates higher than 90% against race 3. Additionally, five of the nine accessions that were tested again had greater than 60% survival against races 1, 3, and 20. These results suggest that the plug-inoculation method can be used as an alternative to the hypocotyl-inoculation method. Potential sources of new P. sojae resistance and/or tolerance may be present in G. soja, but additional genetic research is needed to determine if these sources are different from sources currently found in G. max.

Nutritional evaluation of soybeans varying in trypsin inhibitor content.

A series of experiments was conducted to assess, by various methods, the nutritional value of a raw, Kunitz inhibitor-free, low trypsin-inhibitor soybean variant (LTS) in comparison with raw conventional soybeans (RCS) and heated dehulled soybean meal (HDS). The gross energy, protein, and amino acid concentrations of LTS were similar to those of RCS. The protein quality of the soybeans was compared in two trials in which young chicks were fed 9% or 16% CP diets containing one of the soybeans as the sole source of dietary protein. The protein quality of LTS was superior to that of RCS but inferior to that of HDS. True digestibilities of amino acids and TMEn were determined with a precision-fed cockerel assay using conventional and cecectomized birds. No significant effect of bird type on digestibility was found. The mean digestibility of 16 amino acids in RCS, LTS, and HDS was found to be approximately 68, 83, and 92%, respectively. The TMEn of LTS was greater than that of RCS. Chick growth assays indicated that amino acid bioavailability values of lysine and TSAA for LTS were greater than those for RCS but slightly lower than those for HDS. In an additional chick assay with a corn and HDS diet (22% CP), the dietary HDS protein was replaced with LTS or RCS protein at 25, 50, 75, or 100%. Performance of chicks fed LTS was better than that of chicks fed RCS at all replacement levels, but the difference was not significant at the 25% replacement level. Feed efficiencies of chicks fed 25 or 50% of the dietary soybean protein as LTS were not significantly different from that of chicks fed the corn and HDS control diet. The results of the present study indicated that the nutritive value of LTS is substantially greater than that of RCS but somewhat lower than that of HDS.

Research note: effect of soybeans varying in trypsin inhibitor content on performance of laying hens.

A 6-wk experiment was conducted with commercial laying hens (35 wk of age) to study the effects of feeding raw, conventional, full-fat soybeans (CSB) and raw, Kunitz trypsin inhibitor-free, full-fat soybeans (KFSB) on layer performance. Dietary treatments consisted of corn and soybean meal diets formulated to contain 16% total protein with 100, 72, or 48% of the soybean protein from CSB or KFSB. The remainder of the dietary soybean protein was provided as dehulled soybean meal (DSBM). Egg production, egg weight, egg yield (grams of egg per hen per day) and feed efficiency increased as the level of CSB and KFSB decreased. In general, diets containing KFSB resulted in better performance than those containing CSB. The diet containing 48% of the soybean protein from KFSB yielded performance that was not different (P greater than .05) than that obtained from a corn-DSBM diet. Performance from all other diets was inferior to that from the corn-DSBM diet. Pancreas weight (as a percentage of body weight) was greater for hens fed CSB compared with those fed KFSB, and both were greater than pancreas weight of hens fed the corn-DSBM diet. The dietary treatments had no consistent effect on egg specific gravity or Haugh units.

Nutritional evaluation of lectin-free soybeans for poultry.

This study evaluated the nutritional value of raw lectin-free soybeans in comparison with raw Kunitz trypsin inhibitor-free soybeans, raw conventional soybeans, and commercial heat processed soybean meal (SBM). Analyzed lectin values (milligrams per kilogram) were 7.2, 7.1, and < 0.00015 for the Kunitz-free, conventional, and lectin-free soybeans, respectively. Three experiments were conducted using New Hampshire x Columbian male chicks fed 23% CP dextrose-soybean diets from 8 to 17 d of age. Growth performance of chicks fed lectin-free soybeans was greater (P < 0.05) than that of chicks fed raw conventional soybeans in all three experiments. However, performance of chicks fed lectin-free soybeans was lower than that of chicks fed Kunitz-free soybeans or SBM. The SBM yielded weight gains and feed efficiencies that were much higher than those observed from any of the raw soybeans. True amino acid digestibility and TMEn of the lectin-free and conventional soybeans were determined using the precision-fed cecectomized rooster assay. Seven roosters were crop-intubated with 30 g of soybeans and excreta were collected for 48 h. Digestibility coefficients of most amino acids for lectin-free soybeans were 5 to 8 percentage units higher than those for conventional soybeans, but the differences were not significant (P > 0.05). Likewise, the TMEn for lectin-free soybeans was 11% higher than that for raw conventional soybeans (3.577 vs 3.227 kcal/g DM) but the difference was not significant (P > 0.05). The results of this study indicate that the nutritional value of raw lectin-free soybeans is greater than raw conventional soybeans but is less than raw Kunitz-free soybeans and SBM, suggesting that trypsin inhibitor is a greater antinutritional factor than lectins.

Effect of heating on nutritional quality of conventional and Kunitz trypsin inhibitor-free soybeans.

Five 10-day chick growth experiments and an amino acid digestibility assay were conducted to assess the effect of steam heating on in vivo protein quality of raw, full-fat Kunitz trypsin inhibitor-free soybeans (KFSB) compared with raw, conventional full-fat soybeans (CSB). Protein solubility in .2% KOH was also evaluated as an in vitro test of in vivo protein quality for underprocessed CSB. The CSB and KFSB were autoclaved for 0, 3, 6, 9, 12, 15, 18, or 21 min at 121 C and 124 kPa. The soybeans were then fed to 8- or 9-day-old chicks as the sole source of protein in dextrose and soybean diets containing 23% protein. Growth performance of chicks fed raw KFSB was superior to that of chicks fed raw CSB. Growth performance of chicks fed autoclaved KFSB or CSB increased and pancreas weight (percentage of body weight) decreased as autoclaving time increased. Slightly less autoclaving time was consistently required to achieve maximum chick performance for KFSB compared with CSB. Less autoclaving time was also required to obtain maximum digestibility of amino acids in KFSB compared with CSB. Urease activity of the soybeans decreased as autoclaving time increased, whereas protein solubility in .2% KOH for CSB did not change consistently in response to heating time. The results of the present study indicate that raw KFSB must be heated to obtain maximum protein quality for chicks and that protein solubility in KOH is not a sensitive indicator of underprocessing of CSB soybeans.

Response of young chicks to raw, defatted, Kunitz trypsin inhibitor variant soybeans as sources of dietary protein.

Two trials, using 264 8-day-old male crossbred chicks, were conducted to evaluate the nutritional value of two trypsin-inhibitor (Kunitz) variant soybeans. These two variants, designated PI 157440 (PI) and number 661, have lower trypsin-inhibitor activities than do US commercially grown soybean cultivars such as Amsoy 71. Raw PI, 661, and Amsoy 71 soybeans were defatted and then compared to a commercially processed solvent extracted soybean meal (SBM) using purified diets with soybeans or SBM as the sole source of protein. Trials 1 and 2, respectively, were of 6 and 7 days duration. SBM was superior to each of the raw meals. In Trial 1, gain/feed was higher from PI than from Amsoy 71. In Trial 2, gain and gain/feed were higher (P < .05) from PI and 661 than from Amsoy 71. Pancreas weight as a percent of body weight reflected the trypsin-inhibitor intake. The addition of .3% DL-methionine to each diet improved (P < .05) gain and gain/feed. In Trial 2 gain and gain/feed from PI plus methionine was greater (P < .05) than from 661 plus methionine. In both trials, raw PI plus 3% methionine produced gain and gain/feed comparable to SBM without added methionine.

Pollen from Glycine species survive cryogenic exposure.

Pollen of 12 genotypes of the annual soybean and its wild perennial relatives were stored without pre-desiccation at low temperatures (-20 C and -196 C) and tested for their viability in vitro. The influence of cryopreserved pollen on pod set and seed production was also investigated. Cryopreserved pollen of all the genotypes showed germination in vitro. Pollen of annual soybean stored at -20 C retained their viability for 4 months, however, pollen of its wild perennial relatives at same storage conditions failed to germinate in vitro. Flowers pollinated with cryopreserved pollen had similar pod set and number of seeds/pod as those pollinated with fresh pollen. Results of this study suggest that cryopreservation of pollen can be used successfully for soybean breeding, and also offers the possibility of conserving the haploid gene pool of soybean and wild perennial species in a cryobank facility.

Possible Transfer of Resistance to Heterodera glycines from Glycine tomentella to Glycine max.

Eight wild perennial Glycine species (G. argyrea, G. canescens, G. curvata, G. cyrtoloba, G. latifolia, G. microphylla, G. tabacina, and G. tomentella) were evaluated for resistance to isolates of races 1, 3, and 14 of Heterodera glycines. In a second experiment, reproduction of isolates of races 3, 5, and 14 of H. glycines on five of the wild perennial species was determined. Seventy-one derived fertile lines (2n = 40) that were hybrids between G. max cv Clark 63 and G. tomentella also were evaluated for resistance to isolates of races 3, 5, and 14. All of the wild perennial Glycine species were resistant (Female Indices [FI] less than 10) to all of the isolates that were tested on them. In most cases no females matured. The soybean cvs. Clark 63 and Altona, which were tested at the same time as the hybrids, were susceptible to all isolates of H. glycines tested. When the tests were combined and a single FI calculated with the average number of females on Lee 74, one derived fertile line was resistant to race 3, three derived fertile lines were resistant to race 5, and five derived fertile lines were resistant to race 14. Thus, transfer of resistance to H. glycines from G. tomentella to G. max apparently occurred.

A molecular phylogenetic study of the subtribe Glycininae (Leguminosae) derived from the chloroplast DNA rps16 intron sequences.

Phylogenetic relationships among 13 genera of the subtribe Glycininae, two genera of the allied subtribe Diocleinae that were included within Glycininae by Polhill, and two genera of the subtribe Erythrininae as outgroups were inferred from chloroplast DNA rps16 intron sequence variation. Pairwise sequence divergence values ranged from identity between Teramnus mollis and T. micans and between T. flexilis and T. labialis to 7.89% between Pueraria wallichii and Pseudeminia comosa across all accessions. Phylogenies estimated using parsimony and neighbor-joining methods revealed that (1) Glycininae is monophyletic if Pachyrhizus and Calopogonium (both Diocleinae) are included within Glycininae; (2) the genus Teramnus is closely related to Glycine, and Amphicarpaea showed a sister relationship to the clade comprising Teramnus and Glycine; (3) the expanded Glycininae including two genera of Diocleinae is divided into three branches, temporarily named I (comprising the rest of the examined taxa), II (Pueraria wallichii), and III (Mastersia), but their relationships are equivocal; and (4) the genus Pueraria, regarded as a closely related genus to Glycine, is not monophyletic and should be divided into at least four genera (a hypothesis supported previously by Lackey).

Identification of five new primary simple trisomies in soybean based on pachytene chromosome analysis.

Primary trisomics are ideal cytogenetic tools for associating genes and linkage groups to known chromosomes and testing their independence. In the cultivated soybean, only 8 of the possible 20 primary simple trisomics are known. In this report cytological evidence for the identification of five more new primary simple trisomics, corresponding to chromosomes 6, 8, 12, 16, and 19, is presented for the first time. The precise identification was based on trivalent configuration of chromosomes at the pachynema stage of meiosis, where the chromosomes were identified by their characteristic total length, arm ratio, and distribution of heterochromatin and euchromatin. Cytological observation of chromosome pairing in the 2n = 42 chromosome F1 plants, obtained from eight crosses between known primary trisomics, also supported the identification of primary trisomics in soybean based on pachytene chromosome analysis. Together with the eight primary trisomics identified previously, 13 of the possible 20 primary simple trisomics have been successfully identified, which accounts for about 76% of the total nuclear euchromatin in soybean.

The fine structure of chickpea (Cicer arietinum L.) chromosomes as revealed by pachytene analysis.

A standard pachytene karyotype of chickpea (Cicer arietinum L.) is presented for the first time. Individual pachytene chromosomes were identified and described in detail. An idiogram was prepared on the basis of chromosome length, arm ratio, and distribution of heterochromatin and euchromatin. Chickpea pachytene chromosomes belong to the "differentiated" type with darker staining heterochromatin proximal to and lighter staining euchromatin distal to the centromeres. Chromosomes were numbered from 1 to 8 following a descending order of length. The total length of the chromosome complement at pachytene was 335.33 µ, and chromosome size ranged from 58.05 to 30.53 µ.

Seed protein electrophoresis in taxonomic and evolutionary studies.

Seed protein electrophoresis is increasingly being utilized as an additional approach for species identification and as a useful tool for tracing back the evolution of various groups of plants. This paper summarizes the main features of the seed protein profile - stability, uniformity and additive nature. In addition, the significance of this approach for resolving specific taxonomic and evolutionary problems is pointed out.

The genomic relationships among six wild perennial species of the genus Glycine subgenus Glycine Willd.

Based on meiotic chromosome behavior in intra- and interspecific hybrids, genome symbols were assigned to the following diploid (2n=40) Glycine species: G. canescens = AA; G. clandestina- Intermediate pod (Ip)=A 1 A 1; G. clandestina-Short pod (Sp)=BB; G. latifolia = B 1 B 1; G. tabacina = B 2 B 2; G. cyrtoloba = CC; and G. tomentella = DD. Genome symbol GG was reserved for the soybean, G. max. At metaphaseI, loose chromosome associations were observed in completely sterile interspecific hybrids whose parents differed in their genomes, suggesting some chromosome homologies among species. Although G. clandestina-Sp, G. latifolia and G. tabacina are morphologically distinct species, they differ only by a paracentric inversion. Similar observations were recorded for G. canescens and G. clandestina-Ip. Evidence is presented that demonstrates that G. tabacina (2n=80) and G. tomentella (2n=78, 80) are allotetraploid species complexes. Hybrid weakness, sterility, seedling lethality and seed inviability were found in intra- and interspecific hybrids.

The genomic relationship between Glycine max (L.) Merr. and G. soja Sieb. and Zucc. as revealed by pachytene chromosome analysis.

This study was conducted with the objective of determining the genomic relationship between cultivated soybean (Glycine max) and wild soybean (G. soja) of the subgenus Soja, genus Glycine. Observations on cross-ability rate, hybrid viability, meiotic chromosome pairing, and pollen fertility in F 1 hybrids of G. max × G. soja and reciprocals elucidated that both species hybridized readily and set mature putative hybrid pods, generated vigorous F1 plants, had a majority of sporocytes that showed 18II + 1IV chromosome association at diakinesis and metaphase I, and had a pollen fertility that ranged from 49.2% to 53.3%. A quadrivalent was often associated with the nucleolus, suggesting that one of the chromosomes involved in the interchange is a satellited chromosome. Thus, G. max and G. soja genetic stocks used in this study have been differentiated by a reciprocal translocation. Pachytene analysis of F1 hybrids helped construct chromosome maps based on chromosome length and euchromatin and heterochromatin distribution. Chromosomes were numbered in descending order of 1-20. Pachytene chromosomes in soybean showed heterochromatin distribution on either side of the centromeres. Pachytene analysis revealed small structural differences for chromosomes 6 and 11 which were not detected at diakinesis and metaphase I. This study suggests that G. max and G. soja carry similar genomes and validates the previously assigned genome symbol GG.