Secondary metabolites are involved in the plant stress response. Among these are scopolin and its active form scopoletin, which are coumarin derivatives associated with reactive oxygen species scavenging and pathogen defence. Here we show that scopolin accumulation can be induced in the root by osmotic stress and in the leaf by low-temperature stress in Arabidopsis thaliana. A genetic screen for altered scopolin levels in A. thaliana revealed a mutant compromised in scopolin accumulation in response to stress; the lesion was present in a homologue of THO1 coding for a subunit of the THO/TREX complex. The THO/TREX complex contributes to RNA silencing, supposedly by trafficking precursors of small RNAs. Mutants defective in THO, AGO1, SDS3 and RDR6 were impaired with respect to scopolin accumulation in response to stress, suggesting a mechanism based on RNA silencing such as the trans-acting small interfering RNA pathway, which requires THO/TREX function.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Funding of research by grants to H-P Mock from the EU (ATHENA; KBBE-2009-13) and the BMBF (FKZ 031A108B) are gratefully acknowledged. Antonios Petridis was supported by a post-doctoral fellowship from the Leibniz Association and the German Academic Exchange Service (DAAD). We thank the Salk Institute Genomic Analysis Laboratory for providing the sequence-indexed Arabidopsis T-DNA insertion mutants. Funding for the SIGnAL indexed insertion mutant collection was provided by the National Science Foundation. We also thank the Nottingham Arabidopsis Stock Centre, the GABI-KAT consortium and INRA Versailles for providing further seed stocks. Furthermore we are grateful for the assistance of Katja Witzel (Leibniz Institute of Vegetable and Ornamental Crops, Großbeeren, Germany) with the transcript analysis. We would also like to thank Steffen Neumann (Leibniz Institute for Plant Biochemistry, Halle, Germany) for the upload of LC-MS data into the MetaboLights database.