Commercial Soybean Varieties Research Articles

Chalcone Synthase mRNA and Activity Are Reduced in Yellow Soybean Seed Coats with Dominant I Alleles

The seed of all wild Glycine accessions have black or brown pigments because of the homozygous recessive i allele in combination with alleles at the R and T loci. In contrast, nearly all commercial soybean (Glycine max) varieties are yellow due to the presence of a dominant allele of the I locus (either I or i) that inhibits pigmentation in the seed coats. Spontaneous mutations to the recessive i allele occur in these varieties and result in pigmented seed coats. We have isolated a clone for a soybean dihydroflavonol reductase (DFR) gene using polymerase chain reaction. We examined expression of DFR and two other genes of the flavonoid pathway during soybean seed coat development in a series of near-isogenic isolines that vary in pigmentation as specified by combinations of alleles of the I, R, and T loci. The expression of phenylalanine ammonia-lyase and DFR mRNAs was similar in all of the gene combinations at each stage of seed coat development. In contrast, chalcone synthase (CHS) mRNA was barely detectable at all stages of development in seed coats that carry the dominant I allele that results in yellow seed coats. CHS activity in yellow seed coats (I) was also 7- to 10-fold less than in the pigmented seed coats that have the homozygous recessive i allele. It appears that the dominant I allele results in reduction of CHS mRNA, leading to reduction of CHS activity as the basis for inhibition of anthocyanin and proanthocyanin synthesis in soybean seed coats. A further connection between CHS and the I locus is indicated by the occurrence of multiple restriction site polymorphisms in genomic DNA blots of the CHS gene family in near-isogenic lines containing alleles of the I locus.

Oxidative stability of soybean oils with altered fatty acid compositions

The oxidative stabilities of one canola oil and six soybean oils of various fatty acid compositions were compared in terms of peroxide values, conjugated dienoic acid values and sensory evaluations. Two of the soybean oils (Hardin and BSR 101) were from common commercial varieties. The other four soybean oils were from experimental lines developed in a mutation breeding program at Iowa State University that included A17 with 1.5% linolenate and 15.2% palmitate; A16 with 2% linolenate and 10.8% palmitate; A87‐191039 with 2% linolenate and 29.6% oleate; and A6 with 27.5% stearate. Seed from the soybean genotypes was cold pressed. Crude canola oil was obtained without additives. All oils were refined, bleached and deodorized under laboratory conditions with no additives and stored at 60°C for 15 days. The A17, A16, A87‐191039 and A6 oils were generally more stable to oxidation than the commercial soybean varieties and canola oil as evaluated by chemical and sensory tests. Canola oil was much less stable than Hardin and BSR 101 oils by both chemical and sensory tests. The peroxide values and flavor scores of oils were highly correlated with the initial amounts of linolenate (r=0.95, P=0.001). Flavor quality and flavor intensity had negative correlations with linolenate, (r=−0.89, P=0.007) and (r=−0.86, P=0.013), respectively.

A simple method for the recovery of multiple fertile plants from individual somatic embryos of soybean [Glycine max (L.) merrill

We describe a method for obtaining and proliferating multiple, fertile plants from somatic embryos of several experimental and commercial soybean varieties. Shoot-bud cultures were initiated by placing cotyledonary and torpedo-stage somatic embryos derived from immature seedling cotyledons onto Cheng’s basal medium (CBO) containing 0.5 to 2.5 mg/liter 6-benzyladenine (6-BA). Prolific masses of adventitious shoots were produced within 6 to 18 wk. These cultures can be propagated indefinitely with regular subcultures to CBO containing 0.5 mg/liter 6-BA. Individual shoots were separated from the clusters and were rooted on CBO medium without exogenous growth regulators. By this method any number of plants can be produced from individual somatic embryos. The risk of losing valuable genotypes (e.g., derived from in vitro selection or transformation) due to inefficient embryo germination and embryo-to-plant conversion is thus greatly reduced. Plants were established in the greenhouse and progenies were field tested. Progenies from shoot-bud culture-derived plants showed no somaclonal variation for the seven recessive marker traits or quantitative agronomic characters evaluated under field conditions.

Preferência de alimentação de adultos de Diabrotica speciosa (Germar) e Cerotoma arcuata (Oliv.) em variedades de soja

The preference for feeding in 5 soybean varieties of two species of leaf beetles, D. speciosa (Germar) and C. arcuata (Oliv.) (Coleoptera, Chrysomelidae) was tested at Campinas, State of Sao Paulo, Brazil, under greenhouse conditions, in a free choice type of experiment. Two Brazilian commercial soybean varieties Santa Rosa and Parana, were compared with the PI 227 687, PI 229 358 and PI 171 451. The PI 227.687 was less preferred for feeding by D. speciosa than the commercial varieties and the other two PIs were intermediate. The C. arcuata leaf beetle showed a significant preference for young leaves of the variety Santa Rosa over the young leaves of PI 227.687, but in general there was no conspicuous feeding preference for the commercial varieties as much as there was for D. speciosa.

Variety‐Specific Electrophoretic Variants of Four Soybean Enzymes1

The purpose of this study was to examine the possible use of electrophoresis in soybean (Glycine max (L.) Merr.) variety identification. Seeds from 113 commercial soybean varieties were examined with polyacrylamide slab gel electrophoresis. Distinct variety‐specific electrophoretic zymogams were observed for acid phosphatase (AP), alcohol dehydrogenase (ADH), amylase (AM), tetrazolium oxidase (TO). The varieties displayed one of three banding patterns (zymograms) for each of the four enzymes. In the 4,411 seeds tested for these four enzymes, only four seeds yielded zymograms which were atypical of their respective variety. An additional nine seeds were probably of heterozygous genotype based upon the observed zymograms. Thus, the electrophoretic zymograms were stable varietal characteristics and could be used in varietal identification. Varietal pedigrees constructed from the available records indicated that variant dectrophoretic zymogram patterns were heritable, and that all variants could be traced back to an area of origin.

Utilization of Different Varieties of Raw Soybeans by Male and Female Chicks

Three trials, including 352 male and 96 female 8-day-old chicks, were conducted to compare the nutritional values of a trypsin-inhibitor variant soybean designated 661, and the commercial soybean varieties, Clark and Harosoy. Solvent-extracted soybean meal (SBM) was used as the control protein source. SBM was superior to the raw soybean proteins. Chicks fed raw 661 gained faster (P < .05) and more efficiently and retained more protein than chicks fed raw Clark and Harosoy. Whole body composition and pancreas weights were similar in chicks on the diets containing the different raw soybean varieties. dl-methionine addition (0.3%) improved (P < .01) gain, feed intake, gain/feed and percent protein retention. It also decreased (P < .05) whole body water and protein, increased (P < .05) whole body fat, and increased (P < .01) dry pancreas weight in chicks fed raw soybeans. With methionine supplementation male chicks utilized 661 better than the Harosoy variety, but females responded similarly to both varieties. Both male and female chicks had better gain/feed from SBM than from raw 661 soybeans regardless of methionine supplementation.