“…This work establishes that desmethyl butenolides are preferred substrates for diverse KAI2 homologues, while presenting no detectable bioactivity by D14 homologues. Although karrikins are also KAI2‐specific plant growth regulators, they are inactive in vitro (Waters et al ., 2015a; Waters et al ., 2015b; Yao et al ., 2018; Fukui et al ., 2019; Sun et al ., 2020), do not appear to be active in all plants (Flematti et al ., 2011; Hoffmann et al ., 2014) and have slower and less sensitive activation kinetics in vivo compared with GR24 ent ‐5DS (Wang et al ., 2020). Considering that the preferences of KAI2 and D14 for the two GR24 enantiomers are not always absolute (Scaffidi et al ., 2014; Villaécija‐Aguilar et al ., 2019), we propose that desmethyl butenolide compounds can be used to selectively and potently activate KAI2‐dependent signalling, independently of strigolactone signalling, in a range of species and assays.…”