Molecular Analysis of Soybean Lines with Low Palmitic Acid Content in the Seed Oil

Abstract

Palmitic acid is the major saturated fatty acid found in soybean [Glycine max (L.) Merr.] oil, accounting for approximately 11% of the seed oil content. Reducing the palmitic acid levels of the oil is desirable because of the negative health effects specifically associated with this fatty acid. One of the genetic loci known to reduce the seed palmitate content in soybean is fapnc. Previous studies indicated that fapnc is associated with a deletion in a gene (designated FATB) encoding 16:0‐ACP thioesterase activity. In this report, we isolated full length cDNAs of three of the four unique FATB genes expressed in soybean and show that the isoform designated GmFATB1a represents the specific gene deleted in lines possessing the fapnc locus. Allele specific primers corresponding to GmFATB1a were used to genotype plants from two F4‐derived populations that were segregating for fapnc The GmFATB1a‐specific markers were effective in accounting for 62 to 70% of the genotypic variation in palmitate content in the two populations studied. Because the markers developed in this study are 100% linked to the locus of interest, they should be particularly useful in marker‐assisted selection programs designed to lower the palmitic acid levels of soybean oil.

Mapping the low palmitate fap1 mutation and validation of its effects in soybean oil and agronomic traits in three soybean populations

“…N98-4445 is a F 3 -derived higholeate (563.1 g kg -1 ), low-linoleate (26.3 g kg -1 ;homozygous for fan PI 123440) line that is a sister line of the released germplasm N98-4445A developed by the USDA-ARS in Raleigh, NC (Burton et al 2006). Satelite is a lowpalmitate (39.8 g kg -1 ; homozygous for fap nc and fap1), low-linolenate cultivar (fan PI 123440) (Cardinal et al 2007;Bachlava et al 2008aBachlava et al , b, 2009bCardinal et al 2011). FAHH00 (F 4 derived lines) was derived from the cross of a high yielding line, 'Corsica' (Kenworthy 1996), and N97-3681-11, a low linolenic (fan PI 123440) and low palmitic acid (homozygous for fap nc and fap1) line.…”

“…Southern analysis using the GmFATB cDNA as a probe revealed that multiple copies of the 16:0-ACP thioesterase gene are present in the soybean genome and that the fap nc fap nc genotype has a deletion in one of those copies (Wilson et al 2001a). The mutation in N79-2077-12 (fap nc allele) is caused by a deletion in one of the copies of the 16:0-ACP thioesterase gene (GmFATB1a) and allele-specific markers were developed to be used in marker-assisted selection schemes (Cardinal et al 2007). The mutation in A22 (fap3 allele) is caused by a non-conservative amino acid substitution in the GmFATB1a gene (Vries et al 2011).…”

“…Lines homozygous for the GmFATB1a deletion (homozygous fap nc mutants) had decreased stearic acid (18:0) and increased linoleic acid (18:2) in two populations (Cardinal et al 2007). Similarly, progenies that inherited the major fap nc allele from the cross of N87-2122-4 to two high yielding normal palmitate lines had a 6-15 % reduction in 18:0 (Rebetzke et al 1998b(Rebetzke et al , 2001), a 4-10 % increase in oleic acid (18:1) content in both crosses (Rebetzke et al 1998a(Rebetzke et al , 2001, and an increase in linolenic acid (18:3) content in one cross (Rebetzke et al 1998a).…”

Soybean Oil-Quality Variants Identified by Large-Scale Mutagenesis

“…Other mutants with low levels of palmitic acid (ranging from 5% to 8%) have been identified in previous studies, and at least three nonallelic loci are thought to be involved: fap * , fap1 (C1726), and fap3 (A22) [15][16][17][18][19]. The allele fap nc , which is allelic to fap3, has been associated with mutation of the FAT1B gene [19,20]. Lines 4-9 contain high levels of palmitate, ranging from 12.4% to 16.4%.…”

“…Six mutants containing low levels of oleic acid (lines [18][19][20][21][22][23] were also identified in this study.…”