Biology subjects

VERNOUX, T.

Publications and source records attributed to VERNOUX, T..

3 recordsLinked to original sources

bioRxiv2024

ROS responsive Aux/IAA multimerization modulates auxin responses

Reactive oxygen species (ROS) function as key signals in plants to enable adaptation to environmental stresses. Plant roots respond to transient water stress by temporarily ceasing branching using the acclimative response xerobranching1. In this study, we report that a rapid ROS burst regulates Xerobranching by inducing multimerization of auxin repressor protein IAA3/SHY2. Mutations in specific cysteine residues in IAA3/SHY2 disrupt redox-mediated multimerization and interaction with co-repressor TPL, but not with auxin response partner ARF7 and auxin receptor TIR1. ROS-mediated oligomerization of IAA3/SHY2 is required for efficient ARF mediated target gene repression during Xerobranching and lateral root emergence. We demonstrate that AUX/IAA proteins vary in their redox mediated multimerization, revealing a new auxin response regulatory mechanism that directly connects ROS sensing to auxin signalling. Our study reveals how ROS, auxin and water stress intersect to shape acclimative responses in plant roots and maintain their phenotypic plasticity.

plant biology↗

bioRxiv2022

TPLATE complex dependent endocytosis is required for shoot apical meristem maintenance by 1 attenuating CLAVATA1 signaling

Endocytosis regulates the turnover of cell surface localized receptors, which are crucial for plants to sense and rapidly respond to both endogenous and environmental stimuli. The evolutionarily ancient TPLATE complex (TPC) plays an essential role in clathrin-mediated endocytosis (CME) in Arabidopsis plants. Knockout or strong knockdown of single TPC subunits causes male sterility and seedling lethality phenotypes, complicating analysis of the roles of TPC during plant development. Partially functional alleles of TPC subunits however only cause very mild developmental deviations. Here, we took advantage of the recently reported partially functional TPLATE allele, WDXM2, to investigate a role for TPC-dependent endocytosis in receptor-mediated signalling. We discovered that reduced TPC-dependent endocytosis confers a hypersensitivity to very low doses of CLAVATA3 (CLV3) peptide signalling. This hypersensitivity correlated with the abundance of the CLV3 receptor protein kinase CLAVATA1 (CLV1) at the plasma membrane. Genetic analysis and live-cell imaging revealed that TPC-dependent regulation of CLV3-dependent internalization of CLV1 from the plasma membrane is required for CLV3 function in the shoot. Our findings provide evidence that clathrin-mediated endocytosis of CLV1 is a mechanism to dampen CLV3-mediated signaling during plant development.

plant biology↗

bioRxiv2021

A quantitative gibberellin signalling biosensor reveals a role for gibberellins in internode specification at the shoot apical meristem

Growth at the shoot apical meristem (SAM) is essential for shoot architecture construction. The phytohormones gibberellins (GA) play a pivotal role in coordinating plant growth, but their role in the SAM remains mostly unknown. Here, we developed a ratiometric GA signalling biosensor by engineering one of the DELLA proteins, to suppress its master regulatory function in GA transcriptional responses while preserving its degradation upon GA sensing. We demonstrate that this novel degradation-based biosensor accurately reports on cellular changes in GA levels and perception during development. We used this biosensor to map GA signalling activity in the SAM. We show that high GA signalling is found primarily in cells located between organ primordia that are the precursors of internodes. By gain- and loss-of-function approaches, we further demonstrate that GAs regulate cell division plane orientation to establish the typical cellular organisation of internodes, thus contributing to internode specification in the SAM.

plant biology↗