Genetic Mapping & Complex Traits

These flashcards cover the key concepts and methodologies related to genetic mapping and complex traits, specifically focusing on QTL, their identification, implications for traits like tomato fruit size, and the mechanisms involved in genetic analysis.

What are Quantitative Trait Loci (QTL)?

QTL are regions of the genome that are associated with a quantitative trait, identified using genetic mapping and association of genetic markers.

What is the first step in mapping QTL for quantitative traits?

Make an informative cross between individuals that are inbred relative to each other and which differ at the trait(s) of interest.

What is the purpose of using molecular markers in QTL mapping?

Molecular markers are used to genotype individuals and find markers that co-segregate with the trait of interest.

What does the LOD score represent in genetic mapping?

The LOD score, or logarithm of odds, is a statistical measure used to evaluate the probability of linkage between traits and genes.

What were the outcomes of the study by Anne Frary et al. (2000) regarding tomato fruit size?

The study identified Quantitative Trait Loci controlling tomato fruit size and examined candidate genes related to the size.

What is the significance of the fw2.2 gene in tomato size regulation?

The fw2.2 gene is related to the human proto-oncogene RAS and influences fruit size by repressing it.

How are recombinant inbred lines (RILs) created?

RILs are formed by inbreeding selected individuals across generations to generate unique mosaics of alleles.

What was one method used to test the function of the fw2.2 candidate gene?

Genetic engineering was used to introduce the fw2.2 gene into a large fruit near-isogenic line to test its effect on fruit size.

What is the main objective when plotting the degree of association on a linkage map?

To illustrate the strength of the association between markers and traits using the LOD score.

What is the meaning of 'co-segregation' in the context of genetic traits?

Co-segregation refers to the occurrence of specific genetic markers being inherited together with the trait of interest across generations.