Biology Reference
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are used for the extraction of edible oil from
seeds and kernels, in addition to several other
uses, such as food and fodder. Peanut breed-
ing is more frequently performed in the pub-
lic sector rather than by private companies. One
of the largest breeding stations is in ICRISAT
(International Crop Research Institute for the
Semi-Arid Tropics), where the world's largest
peanut collection, of approx. 15,000 accessions,
is housed. Several national breeding programs
are also active, mainly in Asia and African coun-
tries. The most important objective in peanut
breeding is improvement of yield, followed by
acquisition of biotic and abiotic stress tolerance.
Because peanut shows relatively higher drought
tolerance than other legume crops, it is often
cultivated in semidry areas. Thus, drought toler-
ance is one of the most important targets for the
improvement of abiotic stress tolerance in peanut
breeding.
Meanwhile, improvement of quality charac-
teristics in seeds, such as the modification of
chemical components and reduction of aller-
genicity and aflatoxins, are also important targets
in breeding programs for industry use (Dwivedi
et al. 2007). Peanut seeds contain mostly oil,
which makes up 45-51% of the weight of dry
seeds (Lopez et al. 2000). Most of the oil
extracted from peanut is composed of three
major fatty acids, namely, a saturated fatty acid,
a monounsaturated omega-9 fatty acid, and a
polyunsaturated omega-6 fatty acid, known as
palmitic (C16:0), oleic (C18:1), and linoleic
(C18:2), respectively. However, including these
three major fatty acids, up to 12 fatty acids have
been identified in peanuts (Dean et al. 2009).
Oleic and linoleic acids account for 80% of the
fatty acids in peanut oil (oleic acid: 36.67%,
linoleic acid: 15-43%) and determine the quality
of the oil (Norden et al. 1987). Accordingly, the
quality of peanut oil depends on the properties
of the oil, one of which is the oleic/linoleic acid
ratio (O/L ratio).
There is little evidence that a high O/L ratio
affects other agro-morphological characteristics
of groundnut, such as yield, oil content, protein
content, seed size, and so forth (Moore et al.
1989). Oleic acid is a monounsaturated fatty acid
that has the ability to reduce low-density lipopro-
tein (LDL) levels in humans without reducing
the concentration of high-density lipoproteins
(HDLs), while linoleic acid is a polyunsaturated
fatty acid that can decrease the levels of LDL and
HDL, which is unhealthy (Yin and Cui 2006).
Oleic acid is less prone to oxidation and thereby
possesses an extended shelf life. High-oleate
oil makes hydrogenation unnecessary, avoiding
additional costs and the generation of harmful
trans-fatty acids (Chu et al. 2007, Pham et al.
2010). A high oleate diet has been shown to
improve the blood lipoprotein profile, suppress
tumorigenesis, reduce atherosclerosis, and ame-
liorate inflammatory and coronary heart diseases
(Yu et al. 2008; Chu et al. 2009). In addition
to their uses in food, high-oleic oils also have
industrial applications. The industrial oleochem-
icals business is investigating the use of high-
oleic vegetable oils as feedstock for the produc-
tion of numerous products including cosmetics
and machine lubricants (e.g., high-temperature
engine, transmission, hydraulic, gear, and grease
applications) (Butzen and Schnebly 2007). Thus,
increased oleic acid levels in peanut will not only
improve oil stability, but will also support the
health of consumers in addition to providing ben-
efits for industrial applications.
Peanut is an allotetraploid species (AABB
genome;
40). It has been assumed
that the species probably originated via a
single hybridization event between the two
diploid species,
A. duranensis
(AA genome)
and A.
ipaensis
(BB genome) (Krapovickas and
Gregory 1994; Seijo et al. 2004 and 2007). Mod-
ern cultivars are generally classified into four
botanical types, that is, Spanish, Valencia, Vir-
ginia, and Southeast runner, based on their mor-
phological traits. Despite widespread morpho-
logical variations, extremely lower genetic diver-
sity has been observed in peanut germplasms,
a factor that has slowed advances of molecular
genetics and MAS in peanuts (Halward et al.
1991; Kochert et al. 1996). To date, more than
2n
=
4X
=
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