Ultrastructural Localization of Ions. Iii. Distribution of Chloride in Mesophyll Cells of Mangrove (Aegiceras Corniculatum Blanco).

Abstract

Ultrastructural localization of Cl^- by means of a silver ion precipitation technique combined with X-ray energy spectroscopy (EMMA-4 electron microscope plus KEVEX energy dispersive analyser) showed the presence of two types of vacuoles in mesophyll cells of mangrove (A. corniculatum Blanco). Type A vacuoles contained large amounts of osmiophilic organic solute and little or no Cl^-, while type B vacuoles were shown to be free of osmiophilic organic solute but to contain significant quantities of Cl^-.

X-ray spectroscopy of electron-opaque deposits in chloroplasts showed the presence of AgCl deposits and deposits of silver in approximately equal proportions. Fine granular deposits in plastoglobuli were also shown to consist of silver. Deposits in the cytoplasmic phase and in the plasmodesmata, however, always consisted of AgCl.

The significance of the two types of vacuoles is discussed in relation to the symplastic or apoplastic transport of Cl^- from conducting tissue to the salt glands.