This one has not been addressed directly yet—not that I’m aware.
However, we do have parallel examples.
When something is required for a Sacrament to be valid, the Church always insists that it be natural. Wine must be made from grapes grown on a vine (yes, “from the vine” is actually specified, although that is somewhat due to Latin vocabulary) , even though it’s possible to make an artificial wine. The holy oils must come from a natural plant. The Oil of the Infirm can come from various plants (not necessarily olive), but it cannot be an artificial oil, it must still be a plant oil.
There are other examples of where the Church always prefers (if not insists) that substances be natural. Altar mensas are to be made from natural stone, artificial flowers are frowned upon, recorded music is not allowed, etc. etc. These later examples don’t go to the validity of a sacrament, so we can’t take that too far.
Given that precedent, I’m certain that if the subject would ever arise, the Church would be consistent and insist that wheat for the Eucharist must be wheat harvested from a plant, not artificially produced.