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Abortion of infection during the Rhizobium meliloti —alfalfa symbiotic interaction is accompanied by a hypersensitive reaction
Author(s) -
Vasse Jacques,
Billy Françoise,
Truchet Georges
Publication year - 1993
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1993.04030555.x
Subject(s) - rhizobium , biology , symbiosis , primordium , mechanism (biology) , botany , root nodule , microbiology and biotechnology , root hair , nodule (geology) , inoculation , biochemistry , bacteria , immunology , genetics , paleontology , philosophy , epistemology , gene
Nodulation, the organogenetic process resulting from the symbiotic interaction between Rhizobium and legumes, is under the feedback control of the plant. However, the autoregulatory mechanisms controlling root nodule formation are poorly understood. In this paper it is shown that alfalfa can react to infection by its symbiont Rhizobium meliloti by eliciting a defence mechanism similar to the hypersensitive reaction (HR) observed in incompatible plant‐pathogen interactions. After the first nodule primordia have been induced, an increasing proportion of infection threads abort in a single or a few root cortical cells in which both symbionts simultaneously undergo necrosis. Autofluorescent, cytochemical and immunolocalization assays revealed that phenolic compounds and proteins associated with defence mechanisms in plants have accumulated in the necrotic cells. These results lead to the proposition that the elicitation of a HR is part of the mechanism by which the plant controls infection and, therefore, regulates nodulation.