Exploration de la cellule végétale par spectroscopie RMN

¹ URA CNRS 576, France ;
² Laboratoires de Résonance Magnétique en Biologie et Médecine, France ;
³ Laboratoire de Physiologie Cellulaire Végétale, DBMS/DSV, CEN, BP 85X, Grenoble Cedex, France.

Résumé

On rappelle d’abord quelle est la nature des informations biologiques significatives qui peuvent être obtenues avec la spectroscopie de rmn haute résolution ³¹P, ¹³C et ¹H, et comment sont réalisées les mesures avec les systèmes végétaux. On présente ensuite l’apport original de la rmn dans plusieurs domaines-clés de la physiologie cellulaire végétale touchant le métabolisme énergétique (glycolyse et respiration cellulaire, photosynthèse, rôle de l’appareil vacuolaire) la régulation du pH cytoplasmique, les cinétiques et flux enzymatiques, les phénomènes de transport.

Abstract

This is a brief review of the work realized in the field of plant cell physiology using nuclear magnetic resonance techniques. First, the main types of informations available from in vivo nmr spectroscopy are exposed relatively to ³¹P, ¹³C and ¹H nuclei.

The experimental conditions allowing registration of nmr spectra of plant cells and tissues with high signal-to-noise ratio are then considered. ³¹P NMR spectroscopy contributes to bring an original insight of the dynamic properties of plant cell energetic metabolism in its different domains : the regulations of the cell respiration and of the cytoplasmic pH are the most investigated, together with the study of phosphorylation kinetics ; unidirectional enzymatic fluxes have been measured in two cases in maize root tips ; the movements of inorganic phosphate through the tonoplaste and the plasmalemmae have been studied in great details. Transport of paramagnetic cations through the different structural elements of plant cells and tissues has also been studied with ³¹P spectroscopy but most work on the subject has been done using ¹H nmr. This one is mainly employed to study water exchange through the cellular and tissue compartments as well as water distribution and transport through the plant with the nmr imaging techniques.