PCR products form with DNA, but not with c-DNA - (Aug/12/2011 )

Hi,

I am currently trying to test gene expression of a transgene (inserted in poplar) using q-PCR. I designed primers and tested them first on DNA and obtained bands on an agarose gel (got bands for the positive control as well). Then, I tried testing the primers on c-DNA. While I got bands for ubiquitin, I did not get any bands for my primers. What could be the possible reasons? Any advice on how to proceed would be appreciated. I have the gel pictures and can upload them if required.

Thanks in advance.

How do you designed your primers? They're obviously not intron spanning, but are you sure they're not located in the intron part of a gene? Or your transgene doesn't contain introns?
Other reason may be, that your transgene is simply not expressed.

Thanks for your reply. I checked; the primers don't seem to be located in the intron part.