X-Ray Micro-Analysis of Cells and Cell Compartments ofAtripiex spongiosa

Publisher Website
Google Scholar
Abstract
Atripiex spongiosa was grown in hydroponic culture with addition of 0, 50, 200, 400 and 600 mM NaCl. Frozen, hydrated cells of the roots were analysed by X-ray micro-analysis. Comparisons were made of meristematic cells at the root apex and vacuolated cells 5.0 mm from the apex. High selectivitiy for K relative to Na was found for the cytoplasm of meristematic cells and there was little effect of increasing salinity on the ratios Na/K, Cl/K, Na/P and CI/P. In the cell vacuoles of the cortex, selective uptake of K relative to Na also occurred, but to a lesser extent than in the meristematic cells. Gradients were found of decreasing ratio of Na/K from the epidermis to the stele. Measurements of chemical content of the roots and shoots of these plants showed that the ratio of Na/K was higher in the shoot than in the cortical cell vacuoles and higher again than in the stele or meristematic cytoplasm. It is suggested that transport of ions to the shoot of Atripiex spongiosa involves selective exclusion of Na from the xylem parenchyma into the xylem, and that this may be general to other halophytes.