On the interrelation of environmental signals and auxin signalling

Prof. Dr. Jürgen Kleine-Vehn (CIBSS-AI), Institute of Biology II, University of Freiburg

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For sessile plants it’s normal to face conditions that induce cellular stress. Multiple biotic and abiotic cues scale biochemical processes, such as protein and lipid synthesis at the endoplasmic reticulum (ER), which is sensed and translated into cellular responses. In plants, “ER-stress” inducing conditions reduce the signalling of the phytohormone auxin. This is highly relevant, because auxin is a master regulator of plant growth. The auxin receptor resides in the nucleus, but there are mounting evidences suggesting a role of the ER in shaping auxin signalling. Our lab has identified the PILS auxin transport facilitators at the ER, where they presumably transport auxin from the cytosol into the ER lumen. Thereby, the PILS proteins suppress nuclear abundance and signalling of auxin (Barbez et al., 2012; Beziat et al., 2017; Feraru et al., 2019; Sun et al., 2020). Mechanistically we propose an integrative signalling hub at the ER membrane, envisioning that auxin and ER homeostasis signalling are interconnected and allow the integration of environmental factors into developmental growth programs.