Biology Reference
In-Depth Information
4
Date Palm
4.1 Introduction
Date palm is grown in an area of 1.2 million hectares mainly in North Africa and
the Middle East, with the production of 7 million metric tons of fruits. Egypt, Iran,
Saudi Arabia, and the United Arab Emirate (UAE) are the major producing countries,
contributing to 57% of the global production (FAOSTAT, 2008). Genomics research
complements classical breeding in characterizing the diversity, developing resistance
to Bayoud disease, identifying sex of the seedling, using probes for detecting brittle
leaf disease, studying proteins involved in major biochemical process, and so on.
4.2 Genetic Diversity using Molecular Markers
4.2.1 Amplified Fragment Length Polymorphism
Amplified fragment length polymorphism (AFLP) is a selective PCR amplifica-
tion of restriction fragments of the total digest of genomic DNA
[1]
. EcorI (E) and
MseI (M) restriction enzymes with triplet nucleotide adapter sequences are used.
AFLP markers generate a large number of scorable bands and were used in the iden-
tification of Californian date cultivars
[2]
. Thirty-one AFLP primers of E-ACC and
M-CAC combinations gave bands, and 15 of them were polymorphic
[3]
in segre-
gating progenies for fruit quality and tolerance to salinity and high humidity. There
are many homonyms and synonyms for names of date varieties, owing to the long
history of cultivation and germplasm exchanges in North Africa. But AFLP profiles
[4]
of similarly named varieties (homonyms) of Bint Aisha (Bent Aisha 1) showed
large AFLP polymorphisms compared to the other three Bint Aisha accessions
[3]
.
Ammry1 and Ammry2 were not the same accessions, although they have similar
names
[3]
. Hence, AFLP markers
[1]
are also helpful in predicting origin in misla-
beled varieties among the homonyms
[4]
and identification of
[2]
genetically similar
and dissimilar date palm varieties.
4.2.2 RAPD, SSR, and ISSR Markers
RAPD and ISSR markers were employed in date palm for characterizing the diver-
sity native to different geographical locations and also to discriminate male and
female palms, and between specific cultivars and wild (
P. canariensis
) and cultivated
(
P. dactylifera
) species. The
Phoenix
genus has many species, of which
P. canar-
iensis
is endemic to the Canary Islands of Spain.
P. dactylifera
palms were also
introduced in the same island and are easily crossed with the
P. canariensis
. Hence,
