Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Pays-Bas → 2002 → Magnetic resonance imaging of plants : plant water status and drought stress response

Wageningen Universiteit (2002)

Magnetic resonance imaging of plants : plant water status and drought stress response

Weerd-Meulenkamp, L. van der

Titre : Magnetic resonance imaging of plants : plant water status and drought stress response

Auteur : Weerd-Meulenkamp, L. van der

Université de soutenance  : Wageningen Universiteit

Grade : Doctor Thesis 2002

Résumé partiel
This Thesis presents an approach for the study of plant water balance during drought stress, using a combination of in vivo NMR experiments and computer simulations. The ultimate aim is the interpretation of the NMR parameters in terms of physiologically relevant characteristics, such as cell dimensions and membrane permeability. Especially the latter has raised a growing interest in plant science, and up to now the measurement of this parameter in vivo was limited to single cells and short experiment time spans.

NMR microscopy of plants yields information on various levels of organisation. The NMR images provide clear anatomical details, which have been used to monitor the response of stem growth rates to osmotic stress. On the tissue and cell levels, the NMR parameters T 2 (transverse spin relaxation time) and D app (apparent diffusion coefficient) provide information on the physical and chemical properties. Correct quantitative values for T 2 and D app are crucial for a useful interpretation. Therefore, Chapter 2 evaluates the accuracy of different fitting procedures.

The physical and chemical properties can vary considerably between and within different tissues, cells, and intracellular compartments, resulting in distinctly different relaxation and diffusion characteristics for these compartments. The interpretation of these parameters is not straightforward. A numerical model of restricted diffusion and relaxation behaviour was therefore developed, based on Fick’s second law of diffusion (Chapter 3). This model expands previous one-dimensional models to a two-dimensional space, consisting of multiple concentric cylindrical compartments, separated by membranes. Numerical simulation experiments using this model demonstrate the importance of modelling two-dimensional diffusion in relation to the effects of spatial restrictions, and spin exchange between the different compartments.

Mots clés : PLANTS / WATER BALANCE / DROUGHT / DROUGHT RESISTANCE / WATER STRESS / PLANT WATER RELATIONS / MEMBRANE PERMEABILITY / CELL GROWTH / NUCLEAR MAGNETIC RESONANCE / MICROSCOPY / COMPUTER SIMULATION / PLANT PHYSIOLOGY

Présentation

Version intégrale (4 Mb)

Page publiée le 17 mars 2006, mise à jour le 2 juin 2022