Oil Composition Variations - Genetics, Genomics and Breeding of Crop Plants - page 263

8.1.5 Differences between Seed and Fruit Oils
When made by the embryo, oil composition is due to both the paternal and
maternal genomes. The genetics of the trait has to be studied on the seed oil
(phenotype) from the seed before planting and not from the seed harvested
in the next generation. Thus, it is required to genotype each seed before
sowing to correlate the phenotype with the molecular markers. This is true
for oil in the embryo, including both seed oil and the fleshy fruit (pericarp)
oil. Pericarp and seed oil of one fruit do not have the same composition, as
has been demonstrated for olive (H. Sommerlatte, pers. comm.). Fleshy
pericarp oil is due to the maternal genome only, whereas seed oil includes
the effect of the genes from the pollen. Consequently, on a sunflower plant,
each seed harvested on an F 1 hybrid plant may have a different oil
composition, whereas on an olive tree, all the fleshy pericarps will have the
same oil composition, but not the shell and embryo oil (Breton et al. 2009).
In the next section, we will examine which genetic events may have led
to the diversity of sunflower oils.
8.2 Mutations Leading to One Main Fatty Acid Accumulated
in Oil
8.2.1 Palmitic Acid
Enhancement of palmitic acid is required for some industrial applications
whereas other applications require reducing both saturated fatty acids,
palmitic and stearic. Thus breeding has followed both these paths.
8.2.2.1 Palmitic Acid in Other Species
High palmitic acid content has been obtained in leaf tissues in Arabidopsis
(Browse et al. 1989). An increased level of palmitic acid in the oil has also
been obtained in soybean. Two mutant soybean lines with palmitic acid
contents of >18% were developed by treatment of 'A1937' seeds with NMU
and “Elgin” seeds with EMS. The mutant lines, A1937NMU-85 and
ElginEMS-421, were crossed to determine their genetic relationship for
elevated palmitic acid content (Fehr et al. 1991). The inheritance of the trait
was controlled by two loci.
In Brassica napus , an induced mutant from European winter oilseed
rape with increased palmitic acid content was phenotypically characterized
and genetically analyzed (Schnurbusch et al. 2000). The mutant showed a
palmitic acid content of 9.2% compared to 4.5% in the parental cultivar. In
contrast, the oleic acid content decreased from 61.6% to 44.2%, whereas the
linoleic and linolenic acid contents increased. The mutant plants grew poorly