Quantitation RT-PCR

[ma]

Dear netter:
Could anyone tell me a good protocol to measure mRNA amount in plant tissues by RT-PCR?
I read a paper in Plant Mol Biol, they used a rat hepatoma cell total RNA as a control.
Is it possible to use the rRNA in plant tissue itself as a internal control and 
synthesized a specific primers to that?( which is like in Northern hybridization) Any 
suggestion or experiences for that is welcome.
Ma