Prostaglandins and related substances in plants

Prostaglandins (PGs) have been detected in many different plants and certain microorganisms. A few prostaglandin-like compounds have also been shown to occur in plants such as flax, Chromolaena morii, and aquatic sedge; and direct precursors (arachidonic acid, di-homo-gamma-linolenic acid and eicosapentaenoic acid) have been detected in a variety of plants and microorganisms, including certain red algae, brown algae, green algae, and saltwater diatoms. Furthermore, arachidonic acid has been found in mosses and a liverwort. It has also been reported that arachidonic acid occurs in certain angiosperms, namely, poplar (Populus balsamifera), wheat germ oil, Aloe vera, and Allium sativum (garlic). In our studies on the possible physiological effects of prostaglandins we found that a PG possibly has an effect on the flowering of the short-day plant Pharbitis nil. It has hastened flower formation by 28 days as compared with controls under inductive conditions (short days), and certain inhibitors of PG-biosynthesis inhibited flowering to a greater or lesser extent. In other physiological studies of prostaglandins, it was found that they have an effect on such aspects as GA(3)-controlled responses in barley endosperm, inhibition of crown gall tumor formation on potato discs, and certain electron-flow reactions in isolated chloroplasts. In corn leaf segments it has an effect on photosynthesis, nucleic acid metabolism, and protein synthesis. The effect on four plant bioassay systems was negligible. It has also been reported that PGs play a role in the regulation of cell membrane permeability.