Non-invasive hydrodynamic imaging in plant roots at cellular resolution

Flavius C Pascut,Darren M Wells,Malcolm J Bennett,Ilda Casimiro,Guilhem Reyt,Christophe Maurel,Monica Calvo-Polanco,Valentin Couvreur,Yann Boursiac,Kevin F Webb,Nicky Leftley,Xavier Draye,Daniela Dietrich,David E Salt

doi:10.1038/s41467-021-24913-z

Abstract

A key impediment to studying water-related mechanisms in plants is the inability to non-invasively image water fluxes in cells at high temporal and spatial resolution. Here, we report that Raman microspectroscopy, complemented by hydrodynamic modelling, can achieve this goal - monitoring hydrodynamics within living root tissues at cell- and sub-second-scale resolutions. Raman imaging of water-transporting xylem vessels in Arabidopsis thaliana mutant roots reveals faster xylem water transport in endodermal diffusion barrier mutants. Furthermore, transverse line scans across the root suggest water transported via the root xylem does not re-enter outer root tissues nor the surrounding soil when en-route to shoot tissues if endodermal diffusion barriers are intact, thereby separating ‘two water worlds’.

Highlights

A key impediment to studying water-related mechanisms in plants is the inability to noninvasively image water fluxes in cells at high temporal and spatial resolution
To demonstrate the feasibility of using Raman microspectroscopy (RMS) to non-invasively image the spatial and temporal dynamics of water isotopes in plant tissues, we initially performed a proof of concept study in root tissues of Arabidopsis thaliana (Fig. 1 and Supplementary Fig. 2)
The D2O pulse was detected solely in inner root tissues and not in outer root tissues, at any point of a 64min experiment composed of wash-in and wash-out phases (Fig. 1C, E)

Summary

Introduction

A key impediment to studying water-related mechanisms in plants is the inability to noninvasively image water fluxes in cells at high temporal and spatial resolution. The spatio-temporal dynamics of water flow is retrieved through an approach combining non-invasive RMS imaging following application of D2O to the root tip, and inverse modeling of D2O advection-diffusion down to the cellular scale.

Results

Conclusion