Question

In 1923, who described the theory of QTL mapping?

• A. Stern
• B. Sax
• C. Mather
• D. Galton

Hint:

QTL mapping began with Sax (1923), linking Mendelian markers to quantitative traits.

Answer 1

The Correct Option is B

Step 1: Define QTL mapping.
QTL = Quantitative Trait Loci. These are genomic regions associated with quantitative traits such as height, yield, or disease resistance.
Step 2: Historical note.
In 1923, Sax was the first to demonstrate the association between a Mendelian marker gene and a quantitative trait, which laid the foundation of QTL mapping.
Step 3: Checking options.
- Stern → Known for genetic recombination studies, not QTL.
- Sax → Correct, 1923 work linked seed coat color and seed size in beans.
- Mather → Worked on polygenic inheritance.
- Galton → Studied biometrics and heredity but not QTL mapping.
Step 4: Conclusion.
Thus, QTL mapping was first described by Sax in 1923.