T. Burgess et al., EFFECT OF FUNGAL-ISOLATE AGGRESSIVITY ON THE BIOSYNTHESIS OF SYMBIOSIS-RELATED POLYPEPTIDES IN DIFFERENTIATING EUCALYPT ECTOMYCORRHIZAS, Planta, 195(3), 1995, pp. 408-417
Changes in protein biosynthesis were examined during the early stages
of differentiation of Eucalyptus grandis-Pisolithus tinctorius ectomyc
orrhizas by two-dimensional polyacrylamide gel electrophoresis of S-35
-labelled proteins. Three distinct isolates of P. tinctorius Coker and
Couch were chosen based on the rate of ectomycorrhizal formation (i.e
. infectivity) with E. grandis W. Hill ex Maiden. The isolate H506 was
not able to induce mycorrhiza, isolate 441 showed moderate infectivit
y and isolate H2144 exhibited a very high infectivity. Mycorrhiza were
produced in vitro in a system where seeds were germinated in the pres
ence of fungal mycelium and exudates. The non-mycorrhizal isolate caus
ed no changes in root protein biosynthesis as analyzed by two-dimensio
nal polyacrylamide gel electrophoresis, whereas drastic alterations in
protein biosynthesis were observed from initial contact with the aggr
essive mycobionts. During mycorrhizal development, there was a marked
inhibition of plant polypeptides synthesis, enhanced accumulation of s
ome fungal polypeptides and the emergence of symbiosis-specific polype
ptides, the so-called ectomycorrhizins. The major changes were observe
d in a group of fungal acidic polypeptides (apparent molecular weight
28-32 kDa) including the ectomycorrhizin E(32). These polypeptides fir
st appeared at contact and their synthesis increased during mycorrhiza
l formation, suggesting a role in mycorrhizal development, most likely
as structural proteins. Up-regulation of the synthesis of fungal symb
iosis-related polypeptides was tightly correlated to the infectivity o
f the strain.