Classic Genetics and Breeding - Genetics, Genomics and Breeding of Crop Plants - page 65

the case of backcross programs, following a cross with the recurrent parent,
to distinguish the offspring which carry the high oleic allele, it may be
necessary to analyze half seed and then grow on the other half, carrying the
plumule and radicle. If lines carrying suppresser effects are eliminated,
high oleic acid content can be bred rapidly, as a major gene character, but to
obtain lines with more than 80% oleic acid (industry would prefer single
fatty acid oils) breeding is quantitative, with selection of plants showing the
highest levels.
Measurement of oleic acid content remains more complicated than
measurement of total oil content. Generally, it is destructive, seed samples
(of 1-2 g) need to be ground and then fatty acid content measured either by
gas chromatography (GPC) or by near-infrared reflectance spectroscopy
(NIRS). This is possible on plants with good seed production or on advanced
generations. Special adaptations are necessary to measure single F 2 seed or
half seeds of backcross programs.
At first, this type of variety appeared of marginal interest, being used to
develop mixed oils for use in commercial food preparations since they can
be heated to higher temperatures than conventional oil. However, in 1990,
nutritional research suggested that an oil with about 60% oleic acid, and a
reduced saturated acid content (as is the case for high oleic sunflower) was
a good dietary element. Mid-oleic varieties were developed in the US,
whereas in Europe, agri-food companies preferred to make their own mix
from high oleic and conventional sunflower. Since 2002, oleic sunflower
have been shown to be of interest not only for food uses, but also for biofuel
production, with the best iodine number of all temperate crops (86, compared
with conventional sunflower: 132, soybean: 130; rapeseed: 117). In many
countries, there has been a considerable change in the type of sunflowers
grown, and it may be suggested that high oleic sunflowers may become the
normal type with what were conventional as “special crops”, for margarine
production or some industrial uses.
After oil extraction, a seed meal is obtained which may be used as animal
food. Its use depends on the proportion of hull it contains, complete grains
providing a meal rich in cellulose that can only be used for ruminants. It
also depends on economic factors, especially the relative price of other seed
meals, especially that of soybean. Studies have been made of seed protein
content, but this character is generally negatively correlated with seed oil
content. The only method of increasing the two is to breed for reduced hull.
This is possible to a certain extent, but the hull must remain sufficient to
protect the embryo in seed production.
The alternative method to obtain a seed meal rich in protein is to hull
seed before oil extraction. In the 1990s, at the time when soybean meal was
expensive, research showed that hullability was correlated with a large
seed and quite high percent hull. It showed heritabilty of 0.8 (Denis et al.