P. Hinde et al., QUANTITATIVE X-RAY-MICROANALYSIS OF SOLUTES IN INDIVIDUAL PLANT-CELLS- A COMPARISON OF MICRODROPLET AND IN-SITU FROZEN-HYDRATED DATA, Journal of Microscopy, 191, 1998, pp. 303-310
Two different approaches to X-ray microanalysis were tested and compar
ed. These were the analysis of sap droplets extracted from individual
cells (plants grown and analysed in Banger, U.K.), and the analysis of
cells in situ in frozen tissue (plants grown and analysed in Hannover
, Germany). The data suggest that both these methods can produce quant
itative data accurately reflecting in vivo concentrations in cereal le
af epidermal cells. The relative merits of the two procedures are disc
ussed with reference to possible sources of error and their applicatio
n to other cell types. Bulk wheat leaf tissue concentrations of K and
Cl did not differ significantly between the two locations, but Ca conc
entration was significantly higher in the plants grown in Hannover. Mi
crodroplet analysis invariably yielded linear responses in the range o
f concentrations found in plant tissue (r(2) for Ca > 0.97, r(2) for K
, Cl > 0.99), and interference of other components of the sap was mini
mal. The calibration curves for the frozen-hydrated material were typi
cally linear in the same range of concentrations (r(2) for K, Ca, Cl >
0.95), and the results for K and Cl concentration in these samples we
re highly consistent with those measured in the microdroplet experimen
ts. In wheat, for example, the cellular Cl concentration varied betwee
n 12 mM and 119 mM, but no significant differences were found between
the two techniques of measurement, The results for cellular Ca differe
d in a manner which might be predicted from the results of the bulk ti
ssue analyses.