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Adaptation of Medicago truncatula to nitrogen limitation is modulated via local and systemic nodule developmental responses
Author(s) -
Jeudy Christian,
Ruffel Sandrine,
Freixes Sandra,
Tillard Pascal,
Santoni Anne Lise,
Morel Sylvain,
Journet EtiennePascal,
Duc Gérard,
Gojon Alain,
Lepetit Marc,
Salon Christophe
Publication year - 2010
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/j.1469-8137.2009.03103.x
Subject(s) - medicago truncatula , biology , mutant , microbiology and biotechnology , adaptation (eye) , stimulation , nitrogen fixation , nodule (geology) , botany , symbiosis , biochemistry , gene , genetics , neuroscience , paleontology , bacteria
Summary• Adaptation of Medicago truncatula to local nitrogen (N) limitation was investigated to provide new insights into local and systemic N signaling. • The split‐root technique allowed a characterization of the local and systemic responses of NO 3 − or N 2 ‐fed plants to localized N limitation. 15 N and 13 C labeling were used to monitor plant nutrition. Plants expressing pMtENOD11‐GUS and the sunn‐2 hypernodulating mutant were used to unravel mechanisms involved in these responses. • Unlike NO 3 − ‐fed plants, N 2 ‐fixing plants lacked the ability to compensate rapidly for a localized N limitation by up‐regulating the N 2 ‐fixation activity of roots supplied elsewhere with N. However they displayed a long‐term response via a growth stimulation of pre‐existing nodules, and the generation of new nodules, likely through a decreased abortion rate of early nodulation events. Both these responses involve systemic signaling. The latter response is abolished in the sunn mutant, but the mutation does not prevent the first response. • Local but also systemic regulatory mechanisms related to plant N status regulate de novo nodule development in Mt , and SUNN is required for this systemic regulation. By contrast, the stimulation of nodule growth triggered by systemic N signaling does not involve SUNN , indicating SUNN ‐independent signaling.