Isothiocyanate-based inhibitors on stomatal opening that act as drought tolerance-conferring agrochemicals

Yusuke Aihara, Ayato Sato, Kei Murakami, Toshinori Kinoshita
Institute of Transformative Biomolecule, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi, JAPAN

Stomatal pores in the plant epidermis open and close to regulate gas exchange between leaves and the atmosphere. Upon light stimulus, the plasma membrane (PM) H+-ATPase is phosphorylated and activated via an intracellular signal transduction pathway in stomatal guard cells, providing a primary driving force for the opening movement. To uncover and manipulate this stomatal opening pathway, we have screened a chemical library and identified several classes of compounds that activate or inhibit stomatal opening. Here we show one of the most potent stomatal opening inhibitors benzyl-isothiocyanate (BITC, a Brassicales-specific metabolite) that suppresses PM H+-ATPase phosphorylation. We further developed BITC-derivatives with higher inhibitory activity on stomatal opening, as well as a longer duration of the effect and negligible toxicity. The limited transcriptomic impact of the improved BITC derivative further highlighted its specificity as a stomatal opening inhibitor. Treatment of the ITC-based inhibitors suppressed plant leaf wilting, elucidating their potential as agrochemicals that confer drought tolerance on plants (Aihara et al., Nat. Commun., 2023). We will also discuss our ongoing research to reveal the molecular mechanism of BITC action on stomatal physiology.