Oil Composition Variations - Genetics, Genomics and Breeding of Crop Plants - page 265

to control low palmitic acid content with additive gene action. In practice,
palmitic acid content and stearic acid content are frequently inversely
correlated.
8.2.2.3 Palmitoleic Acid
Salas et al. ( 2007) have induced a mutation (a high-palmitoleic acid
sunflower mutant) accumulating up to 20% of n -7 fatty acids. This line
produces oil with a complex TAG composition, containing species that have
not been previously identified in sunflower. In this regard, palmitoleic acid
was esterified in an unexpected way in the three positions of the TAG
molecules. The polar glycerolipid composition of the mutant was also
studied, in order to identify and quantify the changes in membrane lipids
imposed by the sunflower enzymatic machinery during the accumulation
of the unusual n -7 fatty acids. The high-palmitoleic mutant accumulated
important quantities of n -7 fatty acids in the polar lipid fraction, especially
in the phosphatidylcholine lipid class. However, the total polar lipid content
of these lines was not affected. On the other hand, the mutations responsible
for the n -7 lipid accumulation induced an important decrease in the oil
yield of the new mutant.
8.2.2 Stearic Acid
8.2.2.1 Stearic Acid in Other Species
Lightner et al. (1994) obtained a high stearic level in Arabidopsis leaves, and
reduced growth of the plants. The fatty acid composition of corn oil has also
been modified for stearic acid content (Jellum and Widstrom 1983). The
inheritance of stearic acid was studied in crosses between standard inbred
lines with approximately 2% stearic acid and three strains of an introduced
genotype (PI 175334) with unusually high stearic acid of about 10%. Results
from single kernel oil analyses of the parents, F 1 , F 2 , BC 1 , and BC 2 generations
strongly suggested the involvement of a major single gene recessive for high
stearic acid in these crosses. Transgressive segregation for high stearic acid
indicated the presence of one or more modifying genes of minor influence
on stearic acid.
8.2.2.2 Stearic Acid in Sunflower
Pérez-Vich et al. (2004) have mapped quantitative trait loci (QTL) conferring
increased C18:0 content in CAS-20 in an F 2 mapping population developed
from a cross between HA-89 (wild type low C18:0) and CAS-20. A genetic
linkage map of 17 linkage groups (LGs) comprising 80 RFLP and 19 SSR