Triflumizole as a Novel Lead Compound for Strigolactone Biosynthesis Inhibitor

Abstract

Strigolactones (SLs) are carotenoid-derived plant hormones involved in the development of various plants. SLs also stimulate seed germination of the root parasitic plants, Striga spp. and Orobanche spp., which reduce crop yield. Therefore, regulating SL biosynthesis may lessen the damage of root parasitic plants. Biosynthetic inhibitors effectively control biological processes by targeted regulation of biologically active compounds. In addition, biosynthetic inhibitors regulate endogenous levels in developmental stage- and tissue-specific manners. To date, although some chemicals have been found as SL biosynthesis inhibitor, these are derived from only three lead chemicals. In this study, to find a novel lead chemical for SL biosynthesis inhibitor, 27 nitrogen-containing heterocyclic derivatives were screened for inhibition of SL biosynthesis. Triflumizole most effectively reduced the levels of rice SL, 4-deoxyorobanchol (4DO), in root exudates. In addition, triflumizole inhibited endogenous 4DO biosynthesis in rice roots by inhibiting the enzymatic activity of Os900, a rice enzyme that converts the SL intermediate carlactone to 4DO. A Striga germination assay revealed that triflumizole-treated rice displayed a reduced level of germination stimulation for Striga. These results identify triflumizole as a novel lead compound for inhibition of SL biosynthesis.

Evaluation of propiconazole, a triazole-containing fungicide as an inhibitor of strigolactone production

“…This suggests that they may inhibit D27, CCD7, or CCD8 enzyme activity. 35) Following the speculation of Kawada et al, 35) triazoles may chelate non-heme iron in the active sites of D27 and CCDs, 36) thereby inhibiting their enzyme activity. Therefore, it is reasonable to suppose that D27 and the CCDs are also targets of this chemical.…”

GR24, A Synthetic Strigolactone Analog, and Light Affect the Organization of Cortical Microtubules in Arabidopsis Hypocotyl Cells

“…Although TIS108 is an inhibitor of P450 cytochrome monooxygenases and thus supposed to be an antagonist of strigolactone function, previous reports have confirmed its inhibitory effect to hypocotyl elongation ( Kawada et al, 2019 , 2020 ). On this basis, the follow-up effects of TIS108 on cortical microtubule organization and dynamics are in line with its observed effects on hypocotyl growth.…”

“…Since the effects of TIS108 are also differentiated between light-grown and etiolated seedlings, it is likely that the TIS108-induced cytoskeletal remodeling is also associated to imbalances in strigolactone signaling. However, TIS108 might be not completely specific to strigolactone biosynthesis, since they target other strigolactone-unrelated CYP450 ( Kawada et al, 2020 ). Hence, future studies have to be supplemented by the use of triflumizole, a novel lead compound for strigolactone biosynthesis ( Kawada et al, 2020 ) as well as Atmax3 and/or Atmax4 strigolactone synthesis mutants, which could both be chemically complemented by the addition of external strigolactones ( Booker et al, 2004 ).…”

“…A triazole-type strigolactone biosynthesis inhibitor, TIS108 (Chiralix, Netherlands), an effective tool for regulating strigolactone production in Arabidopsis (Ito et al, 2013) with some limitations (Kawada et al, 2019(Kawada et al, , 2020, was dissolved in pure acetone prior to use to make a 10 mM stock solution further diluted to 3 µM and 10 µM final concentrations and added to agarose-solidified 1 /2 MS medium. A 0.01% v/v acetone solution in water was used as a mock control for both GR24 and TIS108.…”

Insect growth regulators with hydrazide moiety inhibit strigolactone biosynthesis in rice

“…19) Furthermore, the fungicides tebuconazole and triflumizole have been identified as SL-biosynthesis inhibitors. 20,21) Consequently, it is effective to screen pharmacological agents and agrochemicalsexcept plant growth regulators which affect plant morphologyfor novel lead chemicals as SL-biosynthesis inhibitors.…”