Flavonoid-induced calcium signalling in Rhizobium leguminosarum bv. viciae
Article first published online: 25 AUG 2010
© The Authors (2010). Journal compilation © New Phytologist Trust (2010)
Volume 188, Issue 3, pages 814–823, November 2010
How to Cite
Moscatiello, R., Squartini, A., Mariani, P. and Navazio, L. (2010), Flavonoid-induced calcium signalling in Rhizobium leguminosarum bv. viciae. New Phytologist, 188: 814–823. doi: 10.1111/j.1469-8137.2010.03411.x
- Issue published online: 19 OCT 2010
- Article first published online: 25 AUG 2010
- Received: 23 April 2010Accepted: 28 June 2010
- calcium signalling;
- legume–rhizobium symbiosis;
- Rhizobium leguminosarum bv. viciae
- •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 Ca2+ in the symbiotic signalling pathway activated by flavonoids in Rhizobium leguminosarum bv. viciae.
- •By using aequorin-expressing rhizobial strains, we monitored intracellular Ca2+ dynamics and the Ca2+ dependence of nod gene transcriptional activation.
- •Flavonoid inducers triggered, in R. leguminosarum, transient increases in the concentration of intracellular Ca2+ 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 Ca2+ variations. A Rhizobium strain cured of the symbiotic plasmid responded to inducers with an unchanged Ca2+ signature, showing that the transcriptional regulator NodD is not directly involved in this stage of flavonoid perception and plays its role downstream of the Ca2+ signalling event.
- •These findings demonstrate a key role played by Ca2+ 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.