Hi, 

We used EF-1 elongation factor for different plants, including N. tabacum. Worked for us :) But there are others, please read this:

http://link.springer.com/article/10.1007%2Fs00438-010-0511-1

thanks Alexander, I'm using ubiquitin..but not too sure if it's the best one

I have been using Ubiquitin. it works very well in our lab.

NtUBI (ubiquitin)

Forward primer TCCAGGACAAGGAGGGTAT

Primers primer GAGACCTCAGTAGACAAAGC

Thanks for the sequence Dr. Trivedi

I also use EF-1 alpha elongation factor as internal control. It works well in N. tabacum.