For example, every apple variety out there. Every potato variety out there. Every garlic variety out there. Grape varietals. All gone because their clone lines expired. Not being able to propagate clone lines is why we can't have seedless oranges or watermelon or grapes.

What makes clone lines no longer able to propagate?

> But it is not possible to keep a clone line going indefinitely

What is the mechanism that prevents this?

I am no botanist

But I think the DNA degrades over time

Mēh! What we do not understand about genetics matters more than what we do....

I am no botanist