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| Map Set Name: |
Almond-RD-Parental |
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| Abbreviated Name: |
Almond-RD-Parental |
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| Accession ID: |
58 |
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| Species: |
Prunus amygdalus (Almond) |
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| Map Type: |
Genetic |
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| Map Units: |
cM |
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| Published On: |
01 February, 2010 |
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Description of 2007 map:
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Six tree traits (self-compatibility, blooming date, blooming density,
productivity, leafing date and ripening time) and five pomological
traits (kernel taste, in-shell weight, shell hardness, kernel weight and
double kernel) were studied in an F1 almond progeny of 167 seedlings
from the cross between the French cultivar R1000 and the Spanish
cultivar Desmayo Largueta . In addition, a set of 135 codominant
microsatellites or simple-sequence repeat (SSR) markers developed
from peach, cherry and almond were used for the molecular characterization
of the progeny. A genetic linkage map was constructed with
56 of these SSRs. Cosegregation analysis allowed the identification of
the map positions of two major genes to be confirmed for kernel taste
(Sk) in linkage group five (G5) and for self-incompatibility (S) in G6.
QTLs mapped include two for leafing date (Lf-Q1 and Lf-Q2) in G1
and G4, one for shell hardness (D-Q) in G2, one each for double kernel
(Dk-Q) and productivity (P-Q) in G4, one for blooming date (Lb-Q) in
G4, two for kernel weight (Kw-Q1 and Kw-Q2) in G1 and G4, and two
for in-shell weight (Shw-Q1 and Shw-Q2) in G1 and G2. Four SSR loci
(BPPCT011, UDP96-013, UDP96-003 and PceGA025) were linked to
the important agronomic traits of leafing date, shell hardness,
blooming date and kernel taste. Finally, the development of efficient
marker-assisted selection strategies applied to almond and other
Prunus breeding programmes was also discussed.
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Description of 2010 map:
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Upon crushing, amygdalin present in bitter almonds is hydrolysed to benzaldehyde, which gives a bitter flavour, and to cyanide, which is toxic. Bitterness is attributable to the recessive allele of the Sweet kernel (Sk/sk) gene and is selected against in breeding programmes. Almond has a long intergeneration period due to its long juvenile phase, so breeders must wait 3 or 4 years to evaluate fruit traits in the field. For this reason, it is important to develop molecular markers to distinguish between sweet and bitter genotypes. The Sk gene is known to map to linkage group five (G5) of the almond genome, but its function is still undefined. Candidate genes involved in the amygdalin pathway have been mapped, but none of them were located to G5. We have saturated G5 with additional Simple Sequence Repeats (SSRs) using the progeny from the cross "R1000" x "Desmayo Largueta" and found six SSRs (UDA-045, EPDCU2584, CPDCT028, BPPCT037, PceGA025, and CPDCT016) closely linked to the Sk locus. The genotypes of four of these SSRs flanking the Sk locus, in a number of parents and a few seedlings of the CEBAS-CSIC almond breeding programme, allowed us to estimate the haplotypes of the parents, identifying the marker alleles adequate for an early and highly efficient selection against bitter genotypes. This analysis has established the usefulness of SSRs for screening populations of fruit trees such as almond by an easy, polymerase chain reaction-based method. |
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