Biology Reference
In-Depth Information
3
Oil Palm
3.1 Introduction
Oil palm is the second largest source of edible oil, next only to soybean. It contrib-
utes approximately one-fifth of the world's production of oils and fats, and belongs
to the genus
Elaeis
. There are two important species in the genus
Elaeis
,
E. guineen-
sis
(African oil palm) and
E. oleifera
(American oil palm). African oil palm is com-
mercially cultivated and a high-yielding species. American oil palm is a low-yielding
species, but the oil quality and composition is better than that of the African species.
Both species of oil palm are diploid (2
n
2
x
32) and are crossable. African oil
palm trees are classified into three groups based on fruit morphology. The dura (D)
has a thick shell (but without the ring of fibers) enclosing the endosperm or kernel.
The pisifera (P) is usually female sterile and has no shell, but it has a ring of fibers
enclosing the kernel, whereas the tenera (T) has a thin shell as well as a ring of fib-
ers enclosing the kernel. Tenera hybrids boosted the oil yield by 30% in oil palm,
and the research in oil palm genetics boosted the yield fourfold from 1947 to 1997
[1]
. Many studies and articles cover biotechnology applications in oil palm
[2-6]
. In
this chapter, we review the genomics work on oil palm in depth. Tissue culture is a
successful way to propagate the oil palm crop. But an abnormality of sterile inflores-
cence is noticed in 3-5% of the tissue-cultured palms known as mantled. Transgenic
plants are a reality in oil palm
[7]
, and many foreign genes are successfully incor-
porated in oil palm such as cry1Ac for insect resistance
[8]
; GUS, a reporter gene;
and polyhydroxy butyrate
[9]
for use as bioreactor. Molecular markers, genes, QTL
maps, and transcriptome resources have been studied in oil palm
[2]
more than in
any other palm.
3.2 Markers, QTLS, Omics of Mesocarp, and Shell Thickness
The fruit of the oil palm (
Elaeis guineensis
Jacq.) is a drupe whose thick, fleshy
mesocarp is exceptionally rich in oil content (80% of dry weight), and the spe-
cies hence is the highest oil-yielding crop of the world
[6]
. Shell thickness is the
most important trait in oil palm, which differs between the dura and the pisifera,
the two common fruit forms of oil palm. Dura (
Plate 3.1
) is a form with a thick-
shelled kernel, whereas pisifera (
Plate 3.2
) is a thin-shelled kernel type. Tenera is
a high-yielding hybrid between the dura (
Sh
1
Sh
1
) and the pisifera (
Sh
2
Sh
2
)
forms of oil palms, differing in the trait of shell thickness (
Sh
1
), controlled by a
single locus with two alleles in a codominant fashion in the tenera form (
Sh
1
Sh
2
)
[10,11]
. Pisifera is a mutation in oil palm associated with a failure of lignin and fiber
