Distribution de quelques oligo-éléments dans des cristaux de graines de Raphanus

Abstract

Globoid crystals were studied in the cotyledonary parenchyma of anhydrous seeds of radish (Raphanus sativus L., Brassicaceae) in ultrathin sections after aldehydic fixation. Crystals derived from the same seeds were also isolated, by print techniques without fixation or aqueous phase. Eleven elements (Mg, Al, Si, P, S, K, Ca, Mn, Fe, Cu, Zn) were looked for using transmission electron probe microanalysis and a wave length dispersive X-ray spectrometry (Camebax microprobe). Crystals of various sizes, rich in P, Mg, and Ca, could contain some micro-elements (Mn, Fe, Zn … ) which could be included in the phytine. Other small crystals, stable under radiation and rich in Fe, were low in P. These two sorts were characterized in globoids, in sections and in prints. Other crystals, isolated from dry seeds, rich in Ca, K, and Mg, were poor in P. Finally, long or angular very stable crystals, rich in Al, lacking P, and hence without phytine, could contain other metals (Fe, Cu, Zn … ) which could be included in nonphytinic molecules. A given metal (Fe or Mn … ) can be found in several types of crystals. Several groups of crystals with similar characters (morphology, composition) were defined, either in protein bodies, in ultrathin sections, or in prints.