Sa. Crawford et al., LOCALIZATION OF ALUMINUM IN ROOT APEX CELLS OF 2 AUSTRALIAN PERENNIALGRASSES BY X-RAY-MICROANALYSIS, Australian journal of plant physiology, 25(4), 1998, pp. 427-435
To determine if an increased aluminium (Al) sensitivity is the result
of greater accumulation of Al in root apices, the quantity and distrib
ution of Al in root apex cells of Danthonia linkii Kunth and Microlaen
a stipoides (Labill.) R.Br. was investigated by X-ray microanalysis. S
eedlings were grown in nutrient solution with 0, 185 and 370 mu M tota
l Al for 24 h after which the terminal 5 mm of the roots were excised,
rapidly frozen and embedded using freeze-substitution. Elemental dist
ribution maps of root apices showed that Al had accumulated in the nuc
lei of root cap and meristematic cells in Al-stressed roots of D, link
ii but not in M. stipoides. Al appeared to be co-localised with phosph
orous (P) in the nuclei of these cells. Quantitation of Al revealed th
at Al-stressed root apex cells of D, linkii accumulated significantly
more Al than M. stipoides. Exposure of D. linkii roots to Al resulted
in substantial increases in the P content of root apex cells, and a si
gnificant positive correlation was found between Al and P in both root
cap and meristematic cells. Analysis of intracellular structures show
ed that the majority of Al had accumulated in the nuclei of cells. A s
ignificant positive correlation was found between Al and P in the nucl
ei, but not in the cytoplasm or cell walls. No positive correlation wa
s found between Al and P in root apex cells of M. stipoides.