title: Abscinazole-E3M, a practical inhibitor of abscisic acid 8'-hydroxylase for improving drought tolerance.
abstract: Abscisic acid (ABA) is an essential phytohormone that regulates plant water use and drought tolerance. However, agricultural applications of ABA have been limited because of its rapid inactivation in plants, which involves hydroxylation of ABA by ABA 8'-hydroxylase (CYP707A). We previously developed a selective inhibitor of CYP707A, (-)-Abz-E2B, by structurally modifying S-uniconazole, which functions as an inhibitor of CYP707A and as a gibberellin biosynthetic enzyme. However, its synthetic yield is too low for practical applications. Therefore, we designed novel CYP707A inhibitors, Abz-T compounds, that have simpler structures in which the 1,2,3-triazolyl ring of (-)-Abz-E2B has been replaced with a triple bond. They were successfully synthesised in shorter steps, resulting in greater yields than that of (-)-Abz-E2B. In the enzymatic assays, one of the Abz-T compounds, (-)-Abz-E3M, acted as a strong and selective inhibitor of CYP707A, similar to (-)-Abz-E2B. Analysis of the biological effects in Arabidopsis revealed that (-)-Abz-E3M enhanced ABA's effects more than (-)-Abz-E2B in seed germination and in the expression of ABA-responsive genes. Treatment with (-)-Abz-E3M induced stomatal closure and improved drought tolerance in Arabidopsis. Furthermore, (-)-Abz-E3M also increased the ABA response in rice and maize. Thus, (-)-Abz-E3M is a more practical and effective inhibitor of CYP707A than (-)-Abz-E2B.
authors.affiliation: College of Global-Interdisciplinary Studies, Academic Institute, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Takeuchi
authors.affiliation: Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori 680-0001, Japan.|PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Okamoto
authors.affiliation: Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori 680-0001, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Mega
authors.affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho Tsurumi-ku, Yokohama 230-0045, Japan.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Kanno
authors.affiliation: College of Agriculture, Academic Institute, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.|Reseach Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ohnishi
authors.affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho Tsurumi-ku, Yokohama 230-0045, Japan.
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Seo
authors.affiliation: College of Agriculture, Academic Institute, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.|Reseach Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.|Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Todoroki
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003681:Dehydration / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D010940:Plant Proteins; D054046:Plant Stomata / Q000201:enzymology*; D013312:Stress, Physiological / Q000187:drug effects*; D014230:Triazoles / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D010940:Plant Proteins; D014230:Triazoles; D003577:Cytochrome P-450 Enzyme System; C107203:abscisic acid 8'-hydroxylase