I'll be doing an experiment exposing plants to ABA, then tracking their response to a stressful environment. The cost of ABA from a chemical supplier is absurd, but the expensive ones seem to be HPLC grade or high purity standards....which I don't need.

An alternative is the 2-cis, 4-trans ABA which is synthetic. It's cheaper and available in larger quantity. Can organisms "tell the difference"?