Biology Reference
In-Depth Information
Table 4.3 Sex-Specific Markers in Date Palm
Materials
Methodology
Conclusions
Reference
Root meristem
Chromomycin staining;
confirmation by
confocal microscopy
flow cytometry
Occurrence of sexual
chromosomes carrying
distinctive nucleolar
heterochromatin
[19]
4 dry cultivars, 3
superior pollinators
RAPD and ISSR
Male- or female-specific
bands in OPA10,
OPA12, OPD10
[20]
5 female-specific ISSR
bands
5 females, 3 males
De novo genome
sequencing and SNP
genotyping
1605 SNPs that
segregated with gender
[21]
using tissue culture techniques. But in breeding experiments, predicting the sex of
the seedling well in advance is important, to save the time, land, and labor required
to maintain the desired sex of the plant. In date palm, developmental arrest of ster-
ile sex organs occurs by the end of cell division. It is followed by the precocious
cell differentiation and development of unisexual flowers [18] . Simple root mer-
istem staining with chromomycin is sufficient to identify the sex of the date palm
plant [19] . Three RAPD and five ISSR primers ( Table 4.3 ) were useful in identify-
ing the sex of a date palm plant. These female-specific (OPA10-490, OPA12-750,
OPD10-800) and male-specific (OPA12-370, OPD10-675, HB10-1010, HB9-340,
HB12-375, 814-590, 844A-920) bands [20] could be cloned and sequenced. These
are converted to sequence characterized amplified region (SCAR) markers for fur-
ther validation and used to identify sex at the seedling stage. Recently, de novo
genome sequencing of date palm was attempted [21] for five females and three
males. Many single nucleotide polymorphisms related to sex were identified from
the study.
4.4 Resistance to Bayoud Disease
Bayoud disease of date palm is caused by the fungal pathogen Fusarium oxyspo-
rum f. sp. albedinis (Foa), also known as Fusariosis. The disease first appeared in
the Draa Valley [22] in the south of Morocco in 1870. The pathogen enters the plant
through the roots, producing foliar withering and leading to the death of the tree. It is
the most important disease of the date palm crop and has destroyed nearly 10 million
trees in Morocco (two-thirds of plantations) and more than 3 million trees in Algeria;
it is also found in Argentina and is a serious problem in other date-producing coun-
tries. Two minicircular plasmid-like DNA of size 1346 bp and (U) 1160 bp, sharing
homology, were discovered from the mitochondria of a Moroccan variety of date
 
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