title: Involvement of papain and legumain proteinase in the senescence process of Medicago truncatula nodules.
abstract: The symbiotic interaction between legumes and Rhizobiaceae leads to the formation of new root organs called nodules. Within the nodule, Rhizobiaceae differentiate into nitrogen-fixing bacteroids. However, this symbiotic interaction is time-limited as a result of the initiation of a senescence process, leading to a complete degradation of bacteroids and host plant cells. The increase in proteolytic activity is one of the key features of this process. In this study, we analysed the involvement of two different classes of cysteine proteinases, MtCP6 and MtVPE, in the senescence process of Medicago truncatula nodules. Spatiotemporal expression of MtCP6 and MtVPE was investigated using promoter- β-glucuronidase fusions. Corresponding gene inductions were observed during both developmental and stress-induced nodule senescence. Both MtCP6 and MtVPE proteolytic activities were increased during stress-induced senescence. Down-regulation of both proteinases mediated by RNAi in the senescence zone delayed nodule senescence and increased nitrogen fixation, while their early expression promoted nodule senescence. Using green fluorescent protein fusions, in vivo confocal imaging showed that both proteinases accumulated in the vacuole of uninfected cells or the symbiosomes of infected cells. These data enlighten the crucial role of MtCP6 and MtVPE in the onset of nodule senescence.
authors: UMR INRA 1355, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|CNRS 7254, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|Institut Sophia Agrobiotech (ISA), Université de Nice-Sophia Antipolis, 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.
authors: Olivier
authors: O
authors: Pierre
authors: UMR INRA 1355, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|CNRS 7254, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|Institut Sophia Agrobiotech (ISA), Université de Nice-Sophia Antipolis, 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.
authors: Julie
authors: J
authors: Hopkins
authors: UMR INRA 1355, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|CNRS 7254, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|Institut Sophia Agrobiotech (ISA), Université de Nice-Sophia Antipolis, 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.
authors: Maud
authors: M
authors: Combier
authors: UMR INRA 1355, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|CNRS 7254, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|Institut Sophia Agrobiotech (ISA), Université de Nice-Sophia Antipolis, 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.
authors: Fabien
authors: F
authors: Baldacci
authors: UMR INRA 1355, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|CNRS 7254, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|Institut Sophia Agrobiotech (ISA), Université de Nice-Sophia Antipolis, 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.
authors: Gilbert
authors: G
authors: Engler
authors: UMR INRA 1355, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|CNRS 7254, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|Institut Sophia Agrobiotech (ISA), Université de Nice-Sophia Antipolis, 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.
authors: Renaud
authors: R
authors: Brouquisse
authors: UMR INRA 1355, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|CNRS 7254, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|Institut Sophia Agrobiotech (ISA), Université de Nice-Sophia Antipolis, 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.
authors: Didier
authors: D
authors: Hérouart
authors: UMR INRA 1355, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|CNRS 7254, Institut Sophia Agrobiotech (ISA), 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.|Institut Sophia Agrobiotech (ISA), Université de Nice-Sophia Antipolis, 400 route des Chappes, BP167, F-06903, Sophia-Antipolis Cedex, France.
authors: Eric
authors: E
authors: Boncompagni
mesh_terms: D056668:Cathepsin L / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D003624:Darkness; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D046913:Medicago truncatula / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development* / Q000382:microbiology; D009584:Nitrogen / Q000494:pharmacology; D009586:Nitrogen Fixation / Q000187:drug effects / Q000235:genetics; D010206:Papain / Q000378:metabolism*; D010802:Phylogeny; D021381:Protein Transport / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D053204:Root Nodules, Plant / Q000201:enzymology* / Q000254:growth & development* / Q000382:microbiology; D020579:Sinorhizobium / Q000187:drug effects / Q000502:physiology; D013559:Symbiosis / Q000187:drug effects; D014617:Vacuoles / Q000187:drug effects / Q000382:microbiology; D000099240:Asparaginyl Endopeptidase
chemical_list: D056668:Cathepsin L; D003546:Cysteine Endopeptidases; D009584:Nitrogen; D010206:Papain; D000099240:Asparaginyl Endopeptidase
keywords: Medicago truncatula; Sinorhizobium meliloti; confocal microscopy; legumain; nitrogen-fixing symbiosis; nodule; papain; senescence