T. Burgess et B. Dell, CHANGES IN PROTEIN-BIOSYNTHESIS DURING THE DIFFERENTIATION OF PISOLITHUS - EUCALYPTUS-GRANDIS ECTOMYCORRHIZA, Canadian journal of botany, 74(4), 1996, pp. 553-560
Protein biosynthesis in Pisolithus - Eucalyptus grandis ectomycorrhiza
was related to the stage of ectomycorrhizal development using two-dim
ensional polyacrylamide gel electrophoresis of proteins labelled by in
vivo incorporation of S-35 radiolabelled amino acids. Nineteen-day-ol
d seedlings were radiolabelled and the primary root was divided into 1
-cm segments. With increasing distance from the tip of the primary roo
t, the lateral roots developed as follows: segment 1, no lateral tips;
segment 2, three lateral tips, 1-4 days old; segment 3, five lateral
tips, 3-8 days old; segment 4, five lateral tips, 7-12 days old. Six-d
ay-old ectomycorrhizas were fully formed with a mantle and Hartig net.
During ectomycorrhizal development, there was a decrease in all plant
proteins and differential accumulation of fungal proteins. The apical
segment of the primary root had a biosynthesis profile very similar t
o that of noninoculated roots. By contrast, the other segments of the
primary root, with attached lateral roots, had biosynthesis profiles t
hat were similar to those of the free-living hyphae. Thus, plant biosy
nthesis was shown to be predominantly associated with the primary root
meristem. The domination of the fungal partner in the protein biosynt
hesis of developing ectomycorrhiza is probably a consequence of stimul
ated fungal growth and the corresponding decrease in plant meristemati
c activity. Ectomycorrhizal development was associated with a differen
tial accumulation of fungal polypeptides and the appearance of a group
of symbiosis-related acid fungal polypeptides between 27 and 37 kDa.
As the polypeptides were present in a similar magnitude throughout ect
omycorrhizal development (lateral tips 1-12 days old), it is suggested
that they function as structural proteins associated with mantle form
ation.