I have never personally grown potatoes, so I am not sure, but don't the tubers
grow from the bottom of the stem, near the root collar? If you grafted it onto
the roots of another species, how could it produce tubers?
Sounds to me like trying to graft feathers onto a carp & calling it a flying
fish.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"When you come to a fork in the road, take it." Yogi Berra