The following is a Southern blot of EcoRI-digested DNA of rye plants from two different inbred lines, A and B.
Developed autoradiogram I shows the bands resulting from probing the blot with 32P-labeled cDNA1. Autoradiogram II shows the same Southern blot after it was stripped of probe and reprobed with 32P-labeled cDNA2.

(a) Which bands would you expect to see in the autoradiogram of a similarly probed Southern blot prepared using EcoRI-digested DNA from F₁ hybrid plants produced by crossing the two inbred lines? 

(b) What can you conclude about the gene(s) represented by band a1 on blot I in the two inbreds?

(c) The F₁ plants were crossed to plants possessing only bands a1, a4, and b3. DNA was isolated from several individual progeny and digested with EcoRI. The resulting DNA fragments were separated by gel electrophoresis, transferred to a nylon membrane, and hybridized with radioactive cDNA1 and cDNA2 probes. The following table summarizes the bands present in autoradiograms obtained using DNA from individual progeny.

Interpret these data. Do the data provide evidence for RFLPs? At how many loci? Are any of the RFLPs linked? If so, what are the linkage distances defined by the data?

Transcribed Image Text:

Ц b1 al b2 a2 b3 a3 a4 Plant No. Bands Present al a2 a3 a4 b1 b2 b3 |+ 4 5 8. 10