You can try and use the delta Ct method to get an idea of how your gene is expressed relative to the reference gene, but I don't know what more information you can derive from just one sample with one gene.

Hi Afruza!

I think you need at least two samples for calculation. One of them should be control. You can use 2 delta delta Ct method. Because probably you will check relative quantification of this gene.

Hi Afruza,

I am completely agree with both answers above. Yo need at least another sample to compare with. So you will have Ct(gene) and Ct(housekeeping) data for leaf sample and your control sample. Then you can compare both expression as Huseyin Ozkan said before, using 2deltadeltaCt. This is:

deltaCt(leaf)= Ct(gene) - Ct(housekeeping) from leaf

deltaCt(controlsample)= Ct(gene) - Ct(housekeeping) from your control sample

deltadeltaCt= deltaCt(leaf) - deltaCt(controlsample)

2^-deltadeltaCt to get the expression fold