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M Lalonde

Publications and source records attributed to M Lalonde.

At least 37 records · Page 2Linked to original sources
PubMed1977

Ultrastructural and immunological demonstration of the nodulation of the European Alnus glutinosa (L.) Gaertn. host plant by the North-American Alnus crispa var. mollis Fern. root nodule endophyte.

The inoculation of the European Alnus glutinosa (L.) Gaertn. host plant by a crushed-nodule inoculum, prepared with the North-American Alnus crispa var. mollis Fern. root nodule, was successful. Fluorescein- and ferritin-labelled antibodies, specific against the A. crispa var. mollis root nodule endophyte (Lalonde et al. 1975), demonstrated the idenity of this endophyte in the resulting nodules. The nodulation process of this abnormal host-endophyte system was studied by light and electron microscopy. An excretion of host blebs containing electron-dense polysaccharide material, resulting in the formation of exo-encapsulation threads containing presumptive endophytic bacterial cells, was associated with deformed root hairs. Originating from an exoencapsulation thread, the endophyte penetrates the root hair cell and then migrates as a hypha toward the cortical cells of the root. Its migration in the cortical cells of the primary nodule results in the induction of a lateral root which develops as the true nodule. The ultrastructure of the A. crispa var. mollis endophyte developing in the primary and true nodule of the abnormal A. glutinosa host was similar to the one induced inside its normal A. crispa var. mollis host. The actinomycetal intruder was a branched and septate hypha able to produce septate vesicles. The endophyte was always encapsulated in an electron-dense polysaccharide material surrounded by a host plasma membrane envelope. However, in this abnormal host-endophyte system, the number of primary nodules formed per root system was drastically reduced, and their appearance was delayed by 1 to 2 weeks. The delayed nodules were effective in fixing nitrogen and able to support satisfactory plant growth in a nitrogen-free medium.

Antigens, Bacterial↗
PubMed1975

Ultrastructure of the Alnus crispa var. mollis Fern. root nodule endophyte.

Nitrogen-fixing, field-obtained root nodules of the silky green alder were studied by transmission electron microscopy. The nodule endophyte exhibited a prokaryotic cytology and was present in two forms: the hypha(0.3-1.0mum), which was branched and septate, and the vesicle (3-5mum), which was also septate and developed at the parental hypha tip. Bacteria-like cells, previously observed in light microscopy studies, were not seen in the present work. The actinomycete-like endophyte penetrated through the host cell wall and becane enveloped by a capsular material (0.1mum), the whole being enclosed by host membranes. In some host cells, the endophyte appeared to lyse and become a mass of shrunken debris. The fine structure of the Alnus crispa var. mollis root nodule endophyte was found to be similar to that of other nonleguminous root nodule endophytes.

Bacteria↗
PubMed1975

Demonstration of the isolation of non-infective Alnus crispa var. mollis Fern, nodule endophyte by morphological immunolabelling and whole cell composition studies.

Two filamentous, branched, and septate actinomycetes were isolated from field-collected and from axenic in vitro produced root nodules of Alnus crispa var. mollis Fern. host plant. After their transfer to a chemically defined medium, these nodule isolates could not be distinguished from each other on the basis of morphology, cultural reactions, and whole cell composition and were considered to be the same species. They were morphologically similar to the root nodule endophyte, but were incapable of nodulating aseptic host plants growing in a nitrogen-deficient substrate. Whole cells of the nodule isolates were used for the production of rabbit antibodies. The resulting specific antiisolate antibodies were conjugated with fluorescein isothiocyanate and used in staining tests of the nodule endophyte. The immunofluorescence reactions demonstrated the homology of the nodule isolates with the nodule endophyte. After pectinase degradation of the endophyte capsule, the indirect immunoferritin method corroborated the fluorescent anti-body (FA) staining reactions. There was no antigenic relationship between the nodule isolates and 13 known strains of actinomycetes as determined by the FA techique. Fluorescent antibody reactions of adsorbed conjugates suggested that endophytes of both Alnus crispa var. mollis Fern. and Alnus rugosa (DuRoi) Spreng. root nodules belong to a common serotype. The LL and mesoisomers of diaminopimelic acid were present in similar proportions in the nodule endophyte and in the nodule isolates. Glucose, mannose, and an unknown sugar were the predominant whole cell sugars in the nodule isolates, although trace amounts of arabinose and rhamnose were also displayed. The unknown sugar found in the nodule isolates was also present in trace amounts in the endophyte-suspension hydrolysate.

Actinomycetales↗