Sa. Crawford et S. Wilkens, ULTRASTRUCTURAL-CHANGES IN ROOT CAP CELLS OF 2 AUSTRALIAN NATIVE GRASS SPECIES FOLLOWING EXPOSURE TO ALUMINUM, Australian journal of plant physiology, 24(2), 1997, pp. 165-174
Transmission electron microscopy was used to investigate ultrastructur
al changes in root cap cells of two aluminium-tolerant native grass sp
ecies, Danthonia linkii Kunth and Microlaena stipoides (Labill.) R.Br.
, following exposure to Al. Quantitative differences in root cap cells
and organelles in response to 0-10 ppm aluminium were determined usin
g image analysis of electron micrographs Changes to the size of root c
ap cells due to exposure to Al were similar in the two species with a
low Al concentration (1-2 ppm) resulting in larger cells, while higher
Al levels (5-10 ppm) reduced cell size. In peripheral cap cells of th
e more Al-tolerant M. stipoides, the size of secretory vesicles was no
t affected by exposure to Al, while in peripheral cap cells of the les
s Al-tolerant D. linkii, exposure to Al resulted in significantly smal
ler secretory vesicles being produced Central root cap cells from cont
rol plants of M. stipoides contained 90% more dictyosomes and had 50%
larger amyloplasts than D. linkii. Measurement of mucilage droplets sh
owed that roots of M. stipoides produced much more mucilage than D. li
nkii. Exposure of roots of M. stipoides to Al in the range 2-10 ppm ha
d no effect on the size of mucilage droplets produced. The possible ro
le of mucilage production in aluminium tolerance is discussed.