The following pedigree shows the inheritance of an autosomal recessive trait in
ID: 72064 • Letter: T
Question
The following pedigree shows the inheritance of an autosomal recessive trait in a specific family. This trait is caused by a specific allele “g” at the G/g locus. You have some reason to suspect that the G/g locus is linked to an STR on chromosome 6 called STR27. You obtain blood samples from each member of the family, and perform a PCR reaction on the DNA of each individual that allows for the genotyping of STR27. The results of the PCR reactions are shown below each family member in the pedigree, in a schematic of an agarose gel in which you have loaded the PCR reactions from each family member into a separate well in the gel.
A allele B allele eCalle le D alleleExplanation / Answer
C allele:
Fire blight, incited by the enterobacterium Erwinia amylovora, is a destructive disease of Rosaceae, particularly of apples and pears. There are reports on the molecular mechanisms underlying E. amylovora pathogenesis and how the host activates its resistance mechanism. The host's resistance mechanism is quantitatively controlled, although some major genes might also be involved. Thus far, quantitative trait loci (QTL) mapping and differential expression studies have been used to elucidate those genes and/or genomic regions underlying quantitative resistance present in the apple genome. In this study, an effort is undertaken to dissect the genetic basis of fire blight resistance in apple using both QTL and genome-wide association mapping. On the basis of an F1 pedigree of 'Coop 16' × 'Coop 17' and a genome-wide association study (GWAS) mapping population of Malus accessions (species, old and new cultivars and selections), new QTLs and associations have been identified. A total of three QTLs for resistance to fire blight, with above 95% significant logarithm of odds threshold value of 2.5, have been identified on linkage groups (LGs) 02, 06, and 15 of the apple genome with phenotypic variation explained values of 14.7, 20.1 and 17.4, respectively. Although elevated P-values with signals for marker-trait associations are observed for some LGs, these are not found to be significant. However, a total of 34 significant associations, with P-values 0.02, have been detected including 8 for lesion length at 7 days following inoculation (PL1), 14 for lesion length at 14 days following inoculation (PL2), and 12 for shoot length.
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