Jack & I discussed this a little over PM and the links from Scot really helped;
It seems indeed that plant cells (most tissue) is not as far differencieted as animal/human cells are, and do not have the 'on-off' switched genes. Therefore they can return so to speack to other differentiations;
"A large portion of a plant consists of cells that are not highly differentiated. These are parenchyma cells which make up most of the soft tissues and are involved mostly in food manufacture and storage. They are capable of dedifferentiation so that they can form other highly specialized tissues, even meristemetic cells which are capable of forming shoots and roots under the right circumstances.
(From the links Scot posted)
It seems we were both a bit right;
They can form meristematic cells again, but also other differencieted tissue, without meristem in between, right?
So indeed it should be possible to mass produce a banana into TC going from just a piece of leaf, if you have the right formula to reduce the unacceptably high mutation rates e.g.
For now, If I try, I'll just usa a pup,