While high oleic and low linolenic acid content are of importance to the commodity soybean, the manipulation of raffinose family oligosaccharides (RFOs) is also an important aspect to improving soybean seed components .
In an effort to elevate oleic acid, soybean breeders are currently introgressing two mutant alleles of FAD2 and FAD3 genes into elite backgrounds to develop new soybean cultivars with elevated oleic and reduced linolenic acid (http://unitedsoybean.org/).
TABLE 4: Average concentration of palmitic, stearic, oleic, linoleic, and linolenic acids, and content of saturated, unsaturated (g/100g), and unsaturated/saturated ratio in the analyzed cultivars in the two planting dates.
The PUFA content comprises about 16 g/100 g 18:2n-6 FA (linoleic acid) and 57 g/100 g 18:3n-3 FA (linolenic acid) .
The ratios of oleic, linoleic and linolenic acids to each other are important to the economic and nutritional value of the nut.
Palmitic acid values of these genotypes were ranged from 6.98 to 8.77%, oleic acid ranged from 19.33 to 36.76%, linoleic acid ranged from 41.55 to 59.89%, linolenic acid ranged from 8.44 to 11.0%, steraic acid ranged from 3.22 to 4.99.
The additive nature of the fan allele with the fap alleles and the lack of interaction between palmitic and linolenic acids
made it possible to combine these traits in the line RG1.
The seed oil of common soybean cultivars consists of [approximately equal to] 110 g [kg.sup.-1] palmitic, 40 g [kg.sup.-1] stearic, 240 g [kg.sup.-1] oleic, 540 g [kg.sup.-1] linoleic, and 70 g [kg.sup.-1] linolenic acid
. Genetic manipulation of soybean fatty acid composition can produce soybean oil with specific industrial and nutritional value.
Soybean germplasms with a low content of linolenic acid
were developed from treatment with x-rays or chemical mutagens and further hybridization of mutants (Takagi et al., 1990; Fehr et al., 1992; Rahman and Takagi, 1997; Rahman et al., 1998).
Therefore, the aim of the present study was to evaluate the agronomic performance of a homozygous haploid-derived population segregating for linolenic acid
content in an agricultural environment over 2 yr at two locations.
Studies with Arabidopsis mutants have concluded that genetic modifications affecting FAD2 activity result in a rise of oleic acid concentration and a concomitant reduction of linoleic acid and linolenic acid
concentrations that are mainly expressed in nonphotosynthetic tissues (seeds and roots), and to a lesser extent in leaves (Lemieux et al., 1990; Okuley et al., 1994: Horiguchi et al., 2001).
Comparisons between reduced and normal palmitic acid populations identified significant (P [is less than] 0.05) effects of the major reduced palmitic acid gene on seed yield, plant height, seed oil content, and two fatty acids, oleic and linolenic acid
contents (Table 1).