Sa. Crawford et S. Wilkens, ULTRASTRUCTURAL ASPECTS OF DAMAGE TO LEAVES OF EUCALYPTUS-CAMALDULENSIS BY THE PSYLLID CARDIASPINA RETATOR, Micron, 27(5), 1996, pp. 359-366
The ultrastructural changes to leaf mesophyll cells in River Red Gum,
Eucalyptus camaldulensis Dehnh., which occur during feeding by nymphs
of Cardiaspina relator Froggatt were characterised using Transmission
Electron Microscopy. Image analysis of micrographs revealed that the s
ap-sucking nymphs of C. retator cause a condition in mesophyll cells t
hat closely resembles the cell degeneration described for senescing le
aves of deciduous trees. The most conspicuous change was the breakdown
of the thylakoid membranes in chloroplasts coupled with a massing of
electron-dense globules (plastoglobuli). For psyllid-affected River Re
d Gums, as for senescing leaves of deciduous plants, this change appea
rs to be related to the mobilisation of lipids and proteins. Results w
ere compared to mesophyll cells of naturally senescing leaves of E. ca
maldulensis which had been abscised. These cells showed whole-scale br
eakdown with the chloroplasts remaining intact and functional the long
est as judged by the presence of large starch grains. There was no acc
umulation of plastoglobuli. Mesophyll cells from senescing leaves appe
ared to suffer from severe water stress, indicated by the deformation
of the cell wall and separation of the plasmalemma from the wall. Copy
right (C) 1996 Elsevier Science Ltd