Biology subjects

Vert, G.

Publications and source records attributed to Vert, G..

3 recordsLinked to original sources

bioRxiv2022

Cadmium-induced endocytosis of the broad spectrum root metal transporter of Arabidopsis

Iron is an essential micronutrient for plant growth and development. Under low iron conditions, Arabidopsis plants take up soil iron using the root iron transporter IRT1. In addition to iron, IRT1 also transports others divalent metals including cadmium that consequently accumulates into plant tissues and enters the food chain. IRT1 expression was shown to be regulated at the transcriptional and post-translational levels by its essential metal substrates to maximize iron uptake while limiting the accumulation of zinc, manganese or cobalt. Here, we characterized the regulation of IRT1 by cadmium and uncovered a cadmium-mediated downregulation of IRT1 protein by endocytosis. A short term exposure to cadmium indeed decreased the celle surface levels of IRT1 through endocytosis and degradation. This is mediated through the direct binding of cadmium to histidine residues within the regulatory loop of IRT1. Moreover, we demonstrated that cadmium-induced IRT1 degradation uses ubiquitin-mediated endocytosis driven by the IDF1 E3 ligase. Altogether, this work sheds light on the mechanisms of cadmium-mediated downregulation of IRT1 and offers a unique opportunity to boost plant cadmium uptake in phytoremediation/phytoextraction strategies.

plant biology↗

bioRxiv2022

SUMO/deSUMOylation of the BRI1 brassinosteroid receptor modulates plant growth responses to temperature

Brassinosteroids (BRs) are a class of steroid molecules perceived at the cell surface that act as plant hormones. The BR receptor BRI1 offers a model to understand receptor-mediated signaling in plants and the role of post-translational modifications. Here we identify SUMOylation as a new modification, targeting BRI1 to regulate its activity. BRI1 is SUMOylated in planta on two lysine residues and the levels of BRI1-SUMO conjugates are controlled by the Desi3a SUMO protease. We demonstrate that BRI1 is deSUMOylated at elevated temperature by Desi3a, leading to increased BRI1 interaction with the negative regulator of BR signaling BIK1 and enhancing BRI1 endocytosis. Loss of Desi3a or BIK1 results in increased response to temperature elevation, indicating that BRI1 deSUMOylation acts as a safety mechanism necessary to keep temperature responses in check. Altogether, our work establishes BRI1 deSUMOylation as a molecular crosstalk mechanism between temperature and BR signaling, allowing plants to translate environmental inputs into growth response. SIGNIFICANCE STATEMENTThe brassinosteroid (BR) receptor BRI1 provides a paradigm for understanding receptor-mediated signaling in plants and contribution of post-translational modifications. Here, we show that BRI carries SUMO modifications in planta on two intracellular lysine residues and that temperature elevation triggers BRI1 deSUMOylation mediated by the Desi3a SUMO protease. Importantly, BRI1 deSUMOylation leads to downregulation of BR signaling via increased BRI1 interaction with the BIK1 negative regulator and increased BRI1 endocytosis. Loss of BRI1 deSUMOylation in desi3a mutants boosts plant responses to heat, indicating that BRI1 deSUMOylation acts as a brake to keep temperature responses in check. Our study uncovers a new post-translational modification targeting BRI1 and sheds light on its functional outcome for environmentally-controlled plant growth.

plant biology↗

bioRxiv2021

The receptor kinase SRF3 coordinates iron-level and flagellin dependent defense and growth responses in plants

Iron is critical for host-pathogen interactions. While pathogens seek to scavenge iron to spread, the host aims at decreasing iron availability to reduce pathogen virulence. Thus, iron sensing and homeostasis are of particular importance to prevent host infection and part of nutritional immunity. While the link between iron homeostasis and immunity pathways is well established in plants, how iron levels are sensed and integrated with immune response pathways remain unknown. We identified a receptor kinase, SRF3 coordinating root growth, iron homeostasis and immunity pathways via regulation of callose synthase activity. These processes are modulated by iron levels and rely on SRF3 extracellular and kinase domain which tune its accumulation and partitioning at the cell surface. Mimicking bacterial elicitation with the flagellin peptide flg22 phenocopies SRF3 regulation upon low iron levels and subsequent SRF3-dependent responses. We propose that SRF3 is part of nutritional immunity responses involved in sensing external iron levels.

plant biology↗