Biology subjects

Savourat, P.

Publications and source records attributed to Savourat, P..

3 recordsLinked to original sources

bioRxiv2026

Leaf hydraulics is a core component of plant immunity

Hydathodes at leaf margins mediate guttation of xylem-derived fluids and serve as primary entry sites for adapted vascular bacterial pathogens such as Xanthomonas campestris. Infection of Arabidopsis mutants with fewer hydathodes resulted in spontaneous mesophyll water-soaking and revealed unexpectedly-large pathogen populations explained by direct infection of the mesophyll niche through stomata and subsequent proliferation. Physical blockage of hydathodes also induced mesophyll water-soaking and enhanced bacterial growth in both Arabidopsis and cauliflower leaves. These findings reveal a dual role for hydathodes as primary sites of infection while being essential to restrict pathogen proliferation in nonvascular tissues. More broadly, our study identifies leaf hydraulics and guttation as central components of water immunity in vascular plants.

plant biology↗

bioRxiv2026

Genetic coupling of hydathode formation with leaf morphogenesis maintains water homeostasis

Hydathodes are specialized leaf structures present across vascular plants that allow guttation by connecting the xylem to the external environment through epithem tissue and permanently open water pores. However, the genetic mechanisms controlling their formation and physiological roles remain poorly understood. Here, we identify a genetic regulatory network that controls hydathode formation and links this process to leaf morphogenesis. This network converges on auxin signaling to coordinate the formation of the three hydathode cell types. We further show that epithem development requires sustained cell proliferation with limited endoreduplication. Analysis of hydathode mutants demonstrates that hydathode size and number are required to prevent reversible leaf flooding. Together, these findings establish a genetic framework for hydathode morphogenesis and uncover a central role for hydathodes in maintaining leaf water homeostasis under fluctuating environmental conditions.

plant biology↗

bioRxiv2023

A fully sequenced collection of homozygous EMS mutants for forward and reverse genetic screens in Arabidopsis thaliana

Genetic screens are powerful tools for biological research and are one of the reasons for the success of the thale cress Arabidopsis thaliana as a model species. Here, we describe the whole-genome sequencing of 871 Arabidopsis lines from the Homozygous EMS Mutant (HEM) collection as a novel resource for forward and reverse genetics. With an average 576 high-confidence mutations per HEM line, over three independent mutations altering protein sequence are found on average per gene in the collection. Pilot reverse genetics experiments on reproductive, developmental and physiological traits confirmed the efficacy of the tool for identifying both null and knockdown alleles. The possibility of conducting subtle repeated phenotyping of HEM lines and the immediate availability of the mutations will empower forward genetic approaches. The sequence resource is searchable with the ATHEM web interface (https://lipm-browsers.toulouse.inra.fr/pub/ATHEM/), and the biological material is distributed by the Versailles Arabidopsis Stock Center.

plant biology↗