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VAMP 721a and VAMP 721d are important for pectin dynamics and release of bacteria in soybean nodules
Author(s) -
Gavrin Aleksandr,
Chiasson David,
Ovchinnikova Evgenia,
Kaiser Brent N.,
Bisseling Ton,
Fedorova Elena E.
Publication year - 2016
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.13837
Subject(s) - rhizobia , medicago truncatula , pectin , cell wall , bacteria , pectate lyase , biochemistry , microbiology and biotechnology , polysaccharide , sinorhizobium meliloti , biology , pectinase , chemistry , enzyme , biophysics , symbiosis , genetics
Summary In root nodules rhizobia enter host cells via infection threads. The release of bacteria to a host cell is possible from cell wall‐free regions of the infection thread. We hypothesized that the VAMP 721d and VAMP 721e exocytotic pathway, identified before in Medicago truncatula , has a role in the local modification of cell wall during the release of rhizobia. To clarify the role of VAMP 721d and VAMP 721e we used Glycine max , a plant with a determinate type of nodule. The localization of the main polysaccharide compounds of primary cell walls was analysed in control vs nodules with partially silenced Gm VAMP 721d . The silencing of Gm VAMP 721d blocked the release of rhizobia. Instead of rhizobia‐containing membrane compartments – symbiosomes – the infected cells contained big clusters of bacteria embedded in a matrix of methyl‐esterified and de‐methyl‐esterified pectin. These clusters were surrounded by a membrane. We found that Gm VAMP 721d ‐ positive vesicles were not transporting methyl‐esterified pectin. We hypothesized that they may deliver the enzymes involved in pectin turnover. Subsequently, we found that Gm VAMP 721d is partly co‐localized with pectate lyase. Therefore, the biological role of VAMP 721d may be explained by its action in delivering pectin‐modifying enzymes to the site of release.