Strigolactone

Strigolactones are a group of chemical compounds produced by roots of plants.^[1] Due to their mechanism of action, these molecules have been classified as plant hormones or phytohormones.^[1] So far, strigolactones have been identified to be responsible for three different physiological processes: First, they promote the germination of parasitic organisms that grow in the host plant's roots, such as Striga lutea and other plants of the genus Striga.^[1] Second, strigolactones are fundamental for the recognition of the plant by symbiotic fungi, especially arbuscular mycorrhizal fungi, because they establish a mutualistic association with these plants, and provide phosphate and other soil nutrients.^[1] Third, strigolactones have been identified as branching inhibition hormones in plants; when present, these compounds prevent excess bud growing in stem terminals, stopping the branching mechanism in plants.^[1]

Strigolactones comprise a diverse group, but they all have core common chemical structure,^[1] as shown in the image to the right. The structure is based on a tricyclic lactone linked to a hydroxymethyl butenolide; the former is represented in the figure as the A-B-C part, while the latter is the D part of the molecule.^[1] It is important to note that most strigolactones present variations in the ABC part, but the D ring is quite constant across the different species, which led researchers to suspect that the biological activity relies on this part of the molecule.^[1] Different studies have demonstrated that the activity of the molecules is lost when the C-D section of the molecules is modified.^[1]

Since strigolactones are involved in the signaling pathway required for germination of parasitic species (such as Striga sp.), they have been a proposed target to control pests and overgrowth of these parasitic organism.^[2] Using a molecule similar to strigolactones could be the key to designing a chemical and biological mechanism to stop the colonization of a plant's root by parasitic plants.^[2]