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Modern breeding makes use of molecular markers to select for traits of interest at an early stage. A molecular marker is created using DNA differences (polymorphisms) which are linked (very closely located) with the actual gene that causes the phenotype (e.g. fruit colour). There are two major advantages of molecular markers in breeding: (1) A marker that is tightly linked to a phenotype that appears in fully mature plants, like fruit colour, allows you to predict and select for this phenotype at the seedling stage already and grow mature plants from the selected seedlings only and (2) a genetic marker, once established, can replace the use of difficult phenotyping procedures. The success of a molecular marker depends on how close the molecular marker is located in the genome to the actual gene that causes the phenotype: the further away the marker is from the gene (genetically), the higher the chance of recombinations between the marker and the gene, which may lead to errors in phenotype prediction. Therefore, a DNA polymorphisms found in the causal gene underlying your phenotype of interest is the best possible genetic marker. Thus the main aim of this assignment is to find the gene that causes either red or pink pigmentation of tomato fruit.
Content:
Part 2: The use of biochemical information to find the metabolic basis for pink fruit colour
Part 3: Combining the information to find the causal gene for pink fruit colour
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