Environmental Stability of Carbohydrate Profiles in Different Soybean Genotypes

Abstract

Soybean [Glycine max (L.) Merr.] is an important annual crop. The raffinose family oligosaccharides (RFOs) raffinose and stachyose are antinutritional carbohydrates present in soybean seeds. Consumption of soybean seed products with low RFO reduced flatulence in humans and increased metabolizable energy efficiency in chickens, pigs, and dogs. The development of soybean cultivars producing high metabolizable energy with low antinutritional factors in the seed is one avenue to increase soybean value. The soybean line PI 200508 with low RFO content was previously characterized to have a reduction of seed raffinose synthase enzyme activity. A variant allele of the raffinose synthase 2 gene (RS2) with a 3‐bp deletion leading to the elimination of a single conserved amino acid residue (RS2, rs2W331−) in PI 200508 was associated with the seed RFO phenotype. Another missense allele of RS2 and variant alleles of the RS3 gene have been identified. The objective of this study was to determine the environmental stability of the carbohydrate profiles for soybean lines containing different allele combinations of two key raffinose synthase (RS2 and RS3) genes in two locations over 2 yr. Although this study was conducted with different genetic backgrounds, the results indicated that the carbohydrate profile in soybean seed is mostly determined by RS2 and RS3 genotype, and galactinol and sucrose content were mainly affected by environmental factors. Genotype was the major factor for the RFO content in soybean seeds, and soybean lines with the rs2W331− allele of RS2 were the most stable for sucrose and RFOs over four environments. A novel genetic combination of RS2 and RS3 alleles demonstrated the importance of multiple variant alleles contributing to seed raffinose synthase activity.

Genetic Analysis of Sugar Composition and Its Relationship with Protein, Oil, and Fiber in Soybean

“…This is consistent with the results reported by Cicek et al (2006) using a population of 303 RILs derived from an interspecific cross. These PIs have not been previously reported to possess such specific sugar features, and no genetic connection between them and previously reported lines has been evidenced by molecular marker and/or pedigree information (Hou et al, 2009;Jo et al, 2018). In the present study, no germplasm accession with that high of glucose and/or fructose content was found.…”

“…These lines include five low-raffinose PIs (PI 603443B, PI 358323, PI 603426E, PI 603429A, and PI 612753A; raffinose content < 3 mg g −1 ), one high-sucrose PI (PI 291329; sucrose content > 64 mg g −1 ), 15 PIs with >120 mg g −1 in total sugar content, and four PIs high in both sucrose and total sugar (PI 538395, PI 458827, PI 597651, and PI 597652). These PIs have not been previously reported to possess such specific sugar features, and no genetic connection between them and previously reported lines has been evidenced by molecular marker and/or pedigree information (Hou et al, 2009;Jo et al, 2018). We also confirmed seven high-protein PIs (PI 468909, PI 612758A, PI 468910, PI 319536B, PI 612759B, PI 603712, and PI 597467) with an average of >462 mg g −1 over three environments, in spite of being coupled with a lower oil concentration (130.9-178.9 mg g −1 ).…”

Environmental Stability Study of Soybeans with Modified Carbohydrate Profiles in Maturity Groups 0 to V

“…Previous studies have investigated the stability of soluble carbohydrate profiles of soybean lines having different combinations of RS2 and RS3 alleles with different environmental conditions such as a planting date study, a location study, and a year study in Missouri (Hagely et al, 2013; Bilyeu and Wiebold, 2016; Jo et al, 2018). The current research was to extend the understanding of environmental stability of carbohydrate profiles in soybean seed in multiple soybean production areas in the United States.…”

TILLING by Sequencing: A Successful Approach to Identify Rare Alleles in Soybean Populations

“…Both of these rs2 mutants have reduced levels of raffinose (0.1-0.2% raffinose as a percentage of total seed carbohydrates) relative to lines wild type for RS2 (0.8-1% raffinose) in replicated field tests [8]. Stachyose levels are also reduced in the rs2 single mutant (0.5-2% of total seed carbohydrates) contrasted with 4% of total carbohydrate in wild type lines, and moderate increases in total sucrose levels [8,9]. A biotechnological approach silencing the RS2 gene in soybean seeds also achieved significant reductions in seed RFOs and an increase in sucrose [4].…”

“…A biotechnological approach silencing the RS2 gene in soybean seeds also achieved significant reductions in seed RFOs and an increase in sucrose [4]. Mutation in RAFFINOSE SYNTHASE3 has been shown to reduce RFOs further when combined with a non-functional allele of rs2, resulting in ultra-low levels of raffinose and stachyose of less than 2% as a fraction of total seed carbohydrates [8][9][10][11]. While the decrease in RFO content is desirable for meal digestibility, the alteration of carbohydrate partitioning resulting in increased levels of sucrose, which contributes to the metabolizable energy in soybean meal is an added advantage [12,13].…”