Strigolactones

Strigolactones are a group of closely-related molecules synthesized by most plants.

This is the molecular structure of one of them.

Strigolactones suppress the branching of roots and stems. They also promote growth of the shoot apex. These actions promote plant elongation thus enhancing the plant's ability to compete with other plants for sunlight.

Mutations in genes needed for the synthesis of strigolactones stimulate the development of lateral buds producing a more highly-branched plant than normal. Application of a synthetic strigolactone near the base of these mutant plants inhibits development of lateral buds above and thus restores normal branching.

• promote the germination of some plant seeds. Unfortunately these include seeds of the genus Striga (witchweed) whose developing root invades the root of the strigolactone-secreting host plant (e.g., rice, corn, and sorghum) stealing nutrients from it and causing serious crop losses.
• signal mycorrhizal fungi to connect to the root system forming a mutualistic relationship.