Identification and improvement of isothiocyanate-based inhibitors on stomatal opening to act as drought tolerance-conferring agrochemicals

Stomatal pores regulate gas exchange in leaves. Light stimulates phosphorylation and activation of the plasma membrane (PM) H+-ATPase in guard cells to drive stomatal opening. Using chemical screening, benzyl isothiocyanate (BITC), a Brassicales metabolite, was identified as a potent stomatal-opening inhibitor that suppresses PM H+-ATPase phosphorylation. BITC derivatives with multiple isothiocyanate groups (multi-ITCs) were developed, showing up to 66-fold stronger inhibition, longer-lasting effects, and negligible toxicity. Multi-ITC treatment reduced leaf wilting over short (1.5 h) and long-term (24 h) periods. The study elucidates a biological function of BITC and demonstrates its potential as an agrochemical to confer drought tolerance by suppressing stomatal opening.

Yusuke Aihara, Bumpei Maeda, Kanna Goto, Koji Takahashi, Mika Nomoto, Shigeo Toh, Wenxiu Ye, Yosuke Toda, Mami Uchida, Eri Asai, Yasuomi Tada, Kenichiro Itami, Ayato Sato, Kei Murakami, Toshinori Kinoshita