Sphynolactone-7 (SPL7) is an agonist of Striga hyposensitive to light receptor 7 (ShHTL7), which is found in the parasitic plant S. hermonthica.1 It selectively binds to ShHTL7 (IC50 = 0.31 µM) over ShHTL2-6, ShHTL9-10, and the strigolactone receptor AtD14 at 10 µM but does inhibit ShHTL8 and ShHTL11 (IC50s = 1.2 and 7.8 µM, respectively). SPL7 induces S. hermonthica seed germination in the absence of a host, which is fatal to this obligate parasite, with a minimum effective concentration of 10 fM. It induces suicidal germination of S. hermonthica seeds and decreases the number of plants emerging from the soil, as well as reduces S. hermonthica-induced senescence in maize plants when pre-applied to the soil of co-cultivated maize plants and S. hermonthica seeds at a concentration of 10 nM.
1.Uraguchi, D., Kuwata, K., Hijikata, Y., et al.A femtomolar-range suicide germination stimulant for the parasitic plant Striga hermonthicaScience362(6420)1301-1305(2018)