DNA quality

[Jacob van Dam]

We work with DNA, extracted from plants (potato). We check the quantity,
dilute, add a primer and use regular PCR protocols, where after we run
it on a gel. Nothing special.

But, DNA from some plants (various clones) do behave regularly (and we
obtain regular bands), as others do not react. No matter how many times
we repeat the procedures (even from DNA extraction), the results are the
same.

I have heard that DNA can sometimes be naturally 'encapsulated', as a
kind of (botanical) mechanism for survival, which disables its function.
I am not sure, however, that this explains above laboratory-problem. Has
anybody suggestions?

Thanks,
Jacob van Dam