PLANT PHYSIOLOGY , Vol 101, Issue 2 513-522, Copyright © 1993 by American Society of Plant Biologists
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PLANT-MICROBE INTERACTIONS |
Characterization of a Lectin from Lactarius deterrimus (Research on the Possible Involvement of the Fungal Lectin in Recognition between Mushroom and Spruce during the Early Stages of Mycorrhizae Formation)
M. Giollant, J. Guillot, M. Damez, M. Dusser, P. Didier and E. Didier
Department of Botany and Cryptogamy, Faculty of Pharmaceutical Sciences, University of Clermont I, Clermont-Ferrand, France (M.G., J.G., M.D., M.Dusser)
A lectin (LDetL) was isolated from carpophores of the mushroom Lactarius
deterrimus, a specific symbiont of the spruce, by a combination of
affinity, hydroxylapatite, and gel-filtration chromatography. Its molecular
mass, as determined by gel filtration, is about 37,000 D, and its structure
is dimeric, with two identical subunits assembled by noncovalent bonds. It
appeared homogeneous on high-performance liquid chromatography gel
filtration, but isoelectric focusing revealed microheterogeneity, with a
main band in the pH zone near 6.5. Amino acid analysis showed that LDetL
contains a large proportion of glycine and especially methionine. Hapten
inhibition assay indicated that LDetL is most specific for
[beta]-D-galactosyl(1->3)-D-N-acetyl galactosamine residues. The lectin
was formed in the in vitro-cultivated mycelium, and anti-lectin antibodies
revealed by indirect immunofluorescence the presence of lectin in the cell
wall. Receptor sites for LDetL were found on the roots, especially on the
root hairs, of axenically grown spruce seedlings. The lectin LDL previously
isolated by us from the taxonomically related mushroom Lactarius
deliciosus, a symbiont of the pine, does not bind to the spruce radicle.
This suggests a role of the fungal lectin in recognition and specificity
during the early stages of mycorrhizae formation.