I have been told by rose experts that many of the old varieties that have
been reproduced by cloning over the years are destined to die out
eventually; it is "tired" genetic material and it becomes less viable
each time it is cloned. We are talking hundreds or more years (some
roses varieties have been in cultivation since egyptian times) but the
effects are becoming evident. We certainly want to make sure we don't
put individual species into this position.
>From my understanding, however, tissue culture, although it produces a
high degree of uniformity, is not *completely* "fool-proof" in producing
all clones; some degree of mutation does occur. I know of cases where
tissue culture of a particular variegate form or color of a plant comes
out with a certain small percentage reverting to non-variegated, or a
different color flower. (I realize these numbers are extremely small though)