Question

How can I know linkage from dihybrid selfed?

An example is below:

A glabrous mutant in Ler ecotype (M^LerM^Ler gl gl) was crossed to a WT in Col ecotype (M^ColM^ColGL GL), followed by selfing of the F1 plants. Glabrous mutants were selected from the F2 progeny and three different Markers of known Col/Ler polymorphisms were analyzed. The outcome is indicated in the table below.

	MColMCol gl gl	MColMLer gl gl	MLerMLer gl gl	Total
MP1.1	1	5	3	9
MP3.3	1	4	7	12
CIW11	1	0	9	10

For our mutant, it initially made in Ler, so if linkage, I understand gl should pop up more with Ler. However, as F2 is generated by selfing F1, I cannot use the recombination frequency(RF). Then, how can I claim that there is linkage between gl and Ler gene?

This is all the information that is elaborated on the assignment. I have no idea where to start...

Answer 1

It is evident from the table that the frequency of occurence MLer MLER gl gl is highest for all the three markers used. In case of marker MP3.3 and ClW11 the frequency of MLer MLER gl gl are 7 out of 12 and 9 out of 10 respectively. In case of MP1.1 out of nine, frequency of MLer MLER gl gl is 3 and MCol MLER gl gl is 5 out of 9. In MCol MLER gl gl, Ler gene is also present and it may be linked to gl. We know from our lilhage study that if two genes are linked they will transmit together in most of the cases as is evident in the table here also. So we can say that there is linkeage between gl and Ler gene.