Marker Assisted Selection (MAS)
| Marker |
P(Qj/Mi) |
| QQ |
Qq |
qq |
| AA |
(1-r)2 |
2r(1-r) |
r2 |
| Aa |
r(1-r) |
(1-r)2+r2 |
r(1-r) |
| aa |
r2 |
2r(1-r) |
(1-r)2 |
Let's say r = 0.2 and we use MAS to select (1-r)2
only AA marker genotypes. The array is (1-r)2
of QQ, 2r(1-r) of Qq and r2 of qq genotypes.
We will select (0.32)2 QQ + 0.4(0.8)Qq +
(0.2)2qq.
= 0.64QQ + 32Qq + 0.04qq
We have selected 64% QQ genotypes.
Let's say r = 0.01 and we use MAS to select only AA
marker genotypes. The array is (1-r)2 of
QQ, 2r(1-r) of Qq and r2 of qq genotypes.
We will select (0.99)2QQ + (0.01)(0.99)Qq + (0.01)2qq
= 0.9801QQ + 0.0099Qq + 0.0001qq
We have selected 98% QQ genotypes.
Conclusion - The closer the marker is located to the QTL, the more
effective will be MAS.
