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Research article - Peer-reviewed, 2021

The chemical compound 'Heatin' stimulates hypocotyl elongation and interferes with the Arabidopsis NIT1-subfamily of nitrilases

van der Woude, Lennard; Piotrowski, Markus; Klaasse, Gruson; Paulus, Judith K.; Krahn, Daniel; Ninck, Sabrina; Kaschani, Farnusch; Kaiser, Markus; Novak, Ondrej; Ljung, Karin; Bulder, Suzanne; van Verk, Marcel; Snoek, Basten L.; Fiers, Martijn; Martin, Nathaniel I.; van Der Hoorn, Renier A. L.; Robert, Stephanie; Smeekens, Sjef; van Zanten, Martijn


Temperature passively affects biological processes involved in plant growth. Therefore, it is challenging to study the dedicated temperature signalling pathways that orchestrate thermomorphogenesis, a suite of elongation growth-based adaptations that enhance leaf-cooling capacity. We screened a chemical library for compounds that restored hypocotyl elongation in the pif4-2-deficient mutant background at warm temperature conditions in Arabidopsis thaliana to identify modulators of thermomorphogenesis. The small aromatic compound 'Heatin', containing 1-iminomethyl-2-naphthol as a pharmacophore, was selected as an enhancer of elongation growth. We show that ARABIDOPSIS ALDEHYDE OXIDASES redundantly contribute to Heatin-mediated hypocotyl elongation. Following a chemical proteomics approach, the members of the NITRILASE1-subfamily of auxin biosynthesis enzymes were identified among the molecular targets of Heatin. Our data reveal that nitrilases are involved in promotion of hypocotyl elongation in response to high temperature and Heatin-mediated hypocotyl elongation requires the NITRILASE1-subfamily members, NIT1 and NIT2. Heatin inhibits NIT1-subfamily enzymatic activity in vitro and the application of Heatin accordingly results in the accumulation of NIT1-subfamily substrate indole-3-acetonitrile in vivo. However, levels of the NIT1-subfamily product, bioactive auxin (indole-3-acetic acid), were also significantly increased. It is likely that the stimulation of hypocotyl elongation by Heatin might be independent of its observed interaction with NITRILASE1-subfamily members. However, nitrilases may contribute to the Heatin response by stimulating indole-3-acetic acid biosynthesis in an indirect way. Heatin and its functional analogues present novel chemical entities for studying auxin biology.


chemical genetics; thermomorphogenesis; Arabidopsis; nitrilases; NIT1‐subfamily; Heatin; aldehyde oxidase; PIF4; 1‐iminomethyl‐2‐naphthol; IAN; indole‐3‐acetonitrile

Published in

Plant Journal
2021, volume: 106, number: 6, pages: 1523-1540
Publisher: WILEY

Authors' information

van der Woude, Lennard
Utrecht University
Piotrowski, Markus
Ruhr University Bochum
Klaasse, Gruson
Utrecht University
Paulus, Judith K.
University of Oxford
Krahn, Daniel
University of Oxford
Ninck, Sabrina
University of Duisburg Essen
Kaschani, Farnusch
University of Duisburg Essen
Kaiser, Markus
University of Duisburg Essen
Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology
Palacký University Olomouc
Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology
Ljung, Karin
Umea University
van Verk, Marcel
Utrecht University
Snoek, Basten L.
Utrecht University
Fiers, Martijn
Wageningen University and Research
Martin, Nathaniel I.
Leiden University
van Der Hoorn, Renier A. L.
University of Oxford
Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology
Smeekens, Sjef
Utrecht University
van Zanten, Martijn
Utrecht University

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