VATIS UPDATE Article

An international team led by Salim Al-Babili at King Abdullah University of Science and Technology (KAUST), Saudi Arabia, and Matias Zurbriggen from the University of Dusseldorf (HHU), Germany, has developed a strigolactone sensor that can be genetically encoded into plant cells to help our understanding of plant development. According to Al-Babili, “Strigolactones are unstable and occur at very low concentrations, which make these hormones difficult to study.”

Strigolactones are sensed in plant cells when they bind to a receptor protein known as D14, forming a complex. This binding recruits another protein to the complex, SMXL, which is then degraded, activating downstream responses. The team harnessed this degradation process to develop their innovative sensor. The new strigolactone sensor – which is genetically encoded so that it can be produced within living cells – comprises a version of SMXL coupled to a yellow luminescent enzyme, luciferase, derived from fireflies.

When SMXL degrades, the luciferase is also degraded, resulting in reduced yellow luminescence. To enable quantification of the effect of strigolactones, the sensor also incorporates a green luciferase derived from the sea pansy, an animal related to jellyfish and corals. The green luciferase is produced in the same quantities as SMXL but is not directly attached to it and is therefore not degraded when strigolactones are present. The ratio of the two colors of luminescence gives a very precise measure of the level of strigolactone activity.