“So children, in the olden days, before there were Skittles, there were Tooty Frooties”. “Ok Dad, but what has that got to do with propagation?” “Well son, it’s what I think of when I hear the word totipotency”. Tootyfrootency. See? Once it’s in your head it never leaves. Or maybe it’s just my head….
Anyway, that’s not important right now. Back to the matter at hand; totipotency. First let me say that I am not a plant biologist, any errors in the below are my own, very happy to be corrected in the comments if you know better. Based on my reading though….
Totipotency is the property that plants have whereby the plant cells have the potential to grow into any part of the plant or even a whole new plant. This property is the basis of all asexual (ie not seeds) reproduction in plants.
Plants grown in this way are genetically identical to the parent plant, they are literally clones – exact copies – and will have the same properties (leaf shape, flower colour, growth pattern etc etc).
All propagation techniques except growing from seed take advantage of this totipotency property.
For example when we take a cutting, the reason that we’re advised to make the cuttings in certain places, near a leaf node, or close to the crown, or next to the stem is that those parts of the plant have a higher concentration of cells that are totipotent. The key to totipotency actually working is that the plant cells have to be alive to divide, so that when they do, cells in the base of the cutting can develop into roots, say. So when we say we need to keep a cutting alive for long enough to produce roots, at a cellular level what we are really saying is that we have to keep it alive long enough for the cells to divide and re-divide to produce root cells which make the roots.
Cells which have become differentiated (ie specialised in some way), say to form part of the stem, or the leaf, or the roots, can go through a change by first undifferentiating then redifferentiating. I think of it like the cell reverses and then drives off down a different road. Cells which have not differentiated much can make the switch easier. This is why immature tip cuttings root faster than say hardwood cuttings. The cells in the stem of a tip cutting just haven’t been that kind of cell very long so they can morph into cells that make roots faster. The cells in the stem of hardwood cuttings have been that kind for months at least and are pretty committed to it, they take ages to reverse and drive off down the root road.
All these propagation techniques are mimicking an equivalent process that occurs naturally, evolved over millions of years.
So that’s tootyfrootency. A critical property of plant cells that makes all (or nearly all) of this propagation business possible.
I’ll be back soon with more propagating news.