Q&A: What are strigolactones and why are they important to plants and soil microbes?

What are strigolactones? Strigolactones are signaling compounds made by plants. They have two main functions: first, as endogenous hormones to control plant development, and second as components of root exudates to promote symbiotic interactions between plants and soil microbes. Some plants that are parasitic on other plants have established a third function, which is to stimulate germination of their seeds when in close proximity to the roots of a suitable host plant. It is this third function that led to the original discovery and naming of strigolactones.