None of the previous studies on isoflavone contents have evaluated the same soybean cultivars at the same Isoflavones in soybean [Glycine max (L.) Merr.] may have positive locations during different years. The objective of this impacts on human health. The objective of this study was to determine study was to evaluate the relative importance of genothe role of the genotype, environment, and genotype ϫ environment types, years, locations, and their interactions on isoflainteractions on isoflavone contents of soybean. Nine isoflavones were measured in six cultivars grown at eight locations during 2 yr. The vone contents by testing multiple cultivars at the same mean contents of total isoflavones and six of nine individual isofla-locations during different years. vones were significantly higher in 1996 than 1995. There were significant differences among locations in one or more years for total and MATERIALS AND METHODS individual isoflavone contents. The year ϫ location interactions were The six cultivars used in this experiment were grown by significant due to changes in rank and magnitude among the locations the Iowa State University soybean breeding project in 1995 during the 2 yr. The genotype, genotype ϫ year, genotype ϫ location, and 1996 at eight Iowa locations. Kenwood 94 was a highand genotype ϫ year ϫ location interactions were significant for total yielding commodity-type cultivar, Vinton 81 a large-seeded and individual isoflavone contents. Despite the significant genotype ϫ and high-protein cultivar, IA2011 a large-seeded and highenvironment interactions, the differences between the cultivars with protein cultivar that lacked the lipoxygenase-2 enzyme, and the highest and lowest total and individual isoflavone contents were IA2012, IA2013, and IA2016 were large-seeded cultivars. The relatively consistent among the 16 environments. It should be possible cultivars were grown in three replications of a randomized to breed for isoflavone content as a quantitative trait in a cultivar complete-block design at Ames, Fairfield, Greene, Grand development program.

About 75% of the total P in conventional soybean [Glycine max (L.) Merr.] seed is phytate P, which cannot be readily digested by nonruminant livestock, such as swine and poultry. The phytate P in soybean lines homozygous for the recessive alleles pha1 and pha2 is reduced to about 25% of the total P. The objective of this study was to determine the influence of low phytate (LP) on agronomic and seed traits of soybean. Three populations were developed by crossing three cultivars with normal phytate (NP) to the LP line CX1834‐1‐6. From each population, 10 LP and 10 NP lines were selected and grown in replicated tests at three Iowa environments during 2003. The mean total P of the LP and NP lines was not significantly different, but the mean phytate P, inorganic P, and other P were significantly different for the two types of lines in the three populations. The mean seedling emergence of the LP lines was 45% compared with 68% for the NP lines. The mean differences between the LP and NP lines for the other agronomic and seed traits were not significant in one or more of the populations. On the basis of these results, reduced seedling emergence will be a major factor to consider in the development of commercially viable cultivars with the pha1pha1pha2pha2 genotype for LP.

Reduction of the palmitic acid content of soybean [Glycine max (L.) Merr.] would lower the total saturated fatty acid content of the seed oil. A mutant line, A1937NMU‐173, with ≈30 g kg‐1 less palmitic acid than commercial soybean cultivars was obtained by the treatment of seeds of the cultivar A1937 with N‐nitroso‐N‐methyl‐urea (NMU). To determine the genetic control of the reduced palmitic acid, A1937NMU‐173 was crossed reciprocally to C1726, a line with the fap1 allele that lowers the palmitic acid content. No maternal effect for palmitic acid was observed from the analysis of F1 seeds from reciprocal crosses. The segregation observed from the analysis of individual F2 seeds for palmitic acid content satisfactorily fit a ratio of 9 greater than either parent: 2 within the range of the parents: 5 less tahn either parent. The F2 segregation ratio and the segregation of F3 seeds from F2 plants indicated that A1937NMU‐173 and C1726 have different alleles at two independent loci. The allele in A1937NMU‐137 has temporarily been designed fapx. the genotype fap1 fap1 fapx fapx has ≈ g kg‐1 of palmitic acid, which is the lowest content known in soybean.

A reduction in the phytic acid (phytate) content of soybean [Glycine max (L.) Merr.] seed would improve the bioavailability of P in rations of nonruminant animals containing soybean meal. A soybean mutant with low phytate and increased inorganic P was developed by the USDA‐ARS and Purdue University. The objective of this study was to determine the inheritance of low phytate in a line derived from the mutant. The low‐phytate line was crossed reciprocally to a line with normal phytate. The F1 seeds from the reciprocal crosses had normal phytate, indicating complete dominance for the wild‐type alleles and no maternal effects. The segregation of 210 F2 seeds satisfactorily fit a phenotypic ratio of 15:1 normal to low phytate. The F2–derived lines satisfactorily fit a ratio of 7:8:1 homogeneous normal phytate to segregating to homogeneous low phytate. The segregation ratios indicated that low phytate was controlled by recessive alleles designated pha1 and pha2 at two independent loci that exhibited duplicate dominant epistasis. Both of the alleles must be homozygous to obtain low‐phytate seed.

the -6 position mediated by the enzyme -6 fatty acid desaturase. Okuley et al. (1994) isolated the cDNA en-Soybean [Glycine max (L.) Merr.] oil with elevated oleate content coding the microsomal -6 fatty acid desaturase from would be useful for food and industrial applications that require increased oxidative stability. The first objective of this study was to Arabidopsis thaliana (L.) Heynh. as the Fad2 gene. Hepdetermine if molecular selection for the Fad2-1 deletion associated pard et al. (1996) found two clones encoding -6 fatty with the ol allele in the mid-oleate mutant line M23 could be used acid desaturase in soybean that they designated Fad2-1 to identify mid-oleate individuals in a breeding program. The second and Fad2-2. Heppard et al. (1996) found Fad2-1 to be objective was to determine if modifying genes affect phenotypic exstrongly expressed in developing seeds while Fad2-2 was pression of oleate content in individuals homozygous for the deleexpressed in both vegetative tissue and developing tion from a cross between M23 and Archer, a cultivar with normal seeds. oleate content. The segregation among 88 F 2 plants from the cross Kinoshita et al. (1998) used the cDNA of Fad2-1 and satisfactorily fit a ratio of 1:2:1 homozygous normal (OlOl)/heterozy-Fad2-2 as probes to screen 40 F 2 plants from the cross gous (Olol)/homozygous (olol) for the Fad2-1 deletion on the basis