Striga hermonthica HYPOSENSITIVE TO LIGHT 7 (ShHTL7)

Striga hermonthica HYPOSENSITIVE TO LIGHT 7 (ShHTL7) is a high-affinity strigolactone receptor essential for the germination of the parasitic weed Striga hermonthica, commonly known as witchweed (Tsuchiya et al., 2015 [1]). This protein belongs to the alpha/beta-hydrolase family and has evolved to detect host-derived strigolactones at extremely low concentrations, often in the picomolar range (Toh et al., 2015 [2]). Upon binding a strigolactone molecule, ShHTL7 undergoes a conformational change that allows it to interact with the F-box protein MAX2, triggering a signaling cascade that initiates germination (Uraguchi et al., 2018 [3]). Because Striga causes devastating yield losses in staple crops like maize, sorghum, and millet, ShHTL7 is a primary target for agricultural biotechnology (Conn et al., 2015 [4]). Research focuses on developing suicidal germination agents—potent agonists like Sphynolactone-7 that trigger Striga seeds to germinate in the absence of a host, leading to their death—or specific inhibitors that block the receptor to prevent infestation (Holbrook-Smith et al., 2016 [5]).

Other names

ShKAI2d7KAI2-like protein 7Strigolactone receptor HTL7Witchweed strigolactone receptor 7

Agonists bind to the catalytic pocket of ShHTL7 and undergo hydrolysis, inducing a conformational change that facilitates the recruitment of the F-box protein MAX2. This leads to the ubiquitination and degradation of repressor proteins (such as SMAX1), triggering the germination signaling cascade. Antagonists or inhibitors occupy the binding pocket to prevent strigolactone-induced activation.