At one point in the 1800's, North American vines were sent across the seas to Europe. Just as humans can carry diseases, so can plants. These North American vines carried small insects. The American vines had immunity to the insects, but the European vines did not. The insects were called Phylloxera vastratix. They look like ticks or bed bugs.
These insects spread onto many European vines and killed them off. These insects live on the root system of the vines. The bug sucks from the vine and injects their waste back into the root. This waste kills the vines and they die within a couple of years.
Grafting and the use of hybridization became a popular way to stop the phylloxera. There must be breeding of the European Vitis Vinifera with resistant species, North American vines.
What is Vitis Vinifera? It is the species of vines native to the European region. They have a different taste from vines and grapes from North America.
So to have healthy and safe vines but yet still use the vines of Europe, scientists learned to graft the fruit character of the Vitis Vinifera onto the phylloxera resistant American root. This way these insects will no longer kill vines.
This is how we now have phylloxera resistant vines. This tradition still continues today.
There is much more to know about the process of Grafting and the history of Phylloxera. If you wish to read more please purchase the book Exploring Wine by Steven Kolpan, Brian H. Smith, and Michael A. Weiss.