Tadao Asami

Feb 27, 2025 | nature.com | Yuchen Qu |Tadao Asami |Kazuma Sakoda |Ichiro Terashima |Yu Wakabayashi |Masatoshi Nakajima | +1 more

To meet the escalating food and fuel demands of a growing global population and industry, food production requires a 50% increase by 2050. However, various environmental stresses, such as excessive light, significantly inhibit plant growth and lead to substantial reductions in crop yields. A major contributing factor to such declines is the reduction in photosynthetic capacity. In this study, a chemical-screening system based on standard 96-well plate and tobacco leaf tissue was developed. With this system, several anthraquinone derivatives that could alleviate high light stress from plants were identified. Application of these chemicals induced greater photosynthetic capacities and better plant growth during and after exposure to light stress for 20-96 hours in tobacco, lettuce, tomato and Arabidopsis. Mechanistic investigations unveiled that these chemicals exhibited electron-accepting abilities at PSI in vitro and improve PSI efficiency in vivo, indicating that the photoprotective effect could be a result of PSI acceptor side oxidation induced by these chemicals. Meanwhile, no adverse effects on plant growth were observed in chemical treated plants under non-stressful cultivation conditions. This study implies that anthraquinone derivatives can confer high light stress tolerance in plants, resulting in improved plant photosynthesis and growth in light stress environments. A high-throughput chemical screening system suggests that several chemicals could protect photosynthesis systems from light damage by serving as electron acceptors at the accepter side of PSI, preventing the reaction center from being over-reduced.

Jan 2, 2025 | nature.com | Jianwen Wang |Kai Jiang |Takeshi Nakano |Masaru Tanokura |Takuya Miyakawa |Tadao Asami | +5 more

The smoke-derived butenolides, karrikins (KARs), regulate many aspects of plant growth and development. However, KARs and a plant hormone, strigolactones (SLs), have high resemblance in signal perception and transduction, making it hard to delineate KARs response due to the shortage of chemical-genetic tools. Here, we identify a triazole urea KK181N1 as an inhibitor of the KARs receptor KAI2. KK181N1 selectively depress the KAR-induced phenotypes in Arabidopsis. We further elucidate the antagonistic, KAI2 binding mechanism of KK181N1, showing that KK181N1 binds to the catalytic pockets of KAI2 in a non-covalent binding manner. Our experiments also demonstrate the binding affinity of triazole urea compounds are regulated by the structured water molecule networks. By fine-tuning this network, we successfully develop a more potent derivative of KK181N1. We anticipate that these chemicals will be applicable to the elucidation of KARs biology, especially for discriminating the molecular and physiological aspects of KARs and SL signaling. Here, the triazole urea compound KK181N1 is identified as a Karrikin signaling-specific antagonist with a non-covalent binding mode, contrasting the covalent binding of the D14 antagonist KK094. This chemical tool holds potential in discriminating the KARs and SL signaling.