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Flavonoid‐induced calcium signalling in Rhizobium leguminosarum bv. viciae
Author(s) -
Moscatiello Roberto,
Squartini Andrea,
Mariani Paola,
Navazio Lorella
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.1469-8137.2010.03411.x
Subject(s) - rhizobia , biology , nod factor , rhizobium leguminosarum , rhizobium , nod , microbiology and biotechnology , intracellular , flavonoid biosynthesis , rhizobiaceae , symbiosis , biochemistry , botany , gene , gene expression , genetics , bacteria , transcriptome
Summary• Legume–rhizobium symbiosis requires a complex dialogue based on the exchange of diffusible signals between the partners. Compatible rhizobia express key nodulation ( nod ) genes in response to plant signals – flavonoids – before infection. Host plants sense counterpart rhizobial signalling molecules – Nod factors – through transient changes in intracellular free‐calcium. Here we investigate the potential involvement of Ca 2+ in the symbiotic signalling pathway activated by flavonoids in Rhizobium leguminosarum bv. viciae . • By using aequorin‐expressing rhizobial strains, we monitored intracellular Ca 2+ dynamics and the Ca 2+ dependence of nod gene transcriptional activation. • Flavonoid inducers triggered, in R. leguminosarum , transient increases in the concentration of intracellular Ca 2+ that were essential for the induction of nod genes. Signalling molecules not specifically related to rhizobia, such as strigolactones, were not perceived by rhizobia through Ca 2+ variations. A Rhizobium strain cured of the symbiotic plasmid responded to inducers with an unchanged Ca 2+ signature, showing that the transcriptional regulator NodD is not directly involved in this stage of flavonoid perception and plays its role downstream of the Ca 2+ signalling event. • These findings demonstrate a key role played by Ca 2+ in sensing and transducing plant‐specific flavonoid signals in rhizobia and open up a new perspective in the flavonoid–NodD paradigm of nod gene regulation.