Podlesakova K. auteur aut IRD Fardoux Joël auteur aut IRD Patrel Delphine auteur aut IRD Bonaldi K. auteur aut IRD Novak O. auteur aut IRD Strnad M. auteur aut IRD Giraud Eric auteur aut IRD Spichal L. auteur aut IRD Nouwen Nico auteur aut IRD text journalArticle eng text/pdf born digital access Cytokinins (CK) play an important role in the formation of nitrogen-fixing root nodules. It has been known for years that rhizobia secrete CK in the extracellular medium but whether they play a role in nodule formation is not known. We have examined this question using the photosynthetic Bradyrhizobium sp. strain ORS285 which is able to nodulate Aeschynomene afraspera and A. indica using a Nod-dependent or Nod-independent symbiotic process, respectively. CK profiling showed that the most abundant CK secreted by Bradyrhizobium sp. strain ORS285 are the 2MeS (2-methylthiol) derivatives of trans-zeatin and isopentenyladenine. In their pure form, these CK can activate legume CK receptors in vitro, and their exogenous addition induced nodule-like structures on host plants. Deletion of the miaA gene showed that transfer RNA degradation is the source of CK production in Bradyrhizobium sp. strain ORS285. In nodulation studies performed with A. indica and A. afraspera, the miaA mutant had a 1-day delay in nodulation and nitrogen fixation. Moreover, A. indica plants formed considerably smaller but more abundant nodules when inoculated with the miaA mutant. These data show that CK produced by Bradyrhizobium sp. strain ORS285 are not the key signal triggering nodule formation during the Nod-independent symbiosis but they contribute positively to nodule development in Aeschynomene plants. specialized 084 076 26 10 1232-1238 2013 0894-0282 https://www.documentation.ird.fr/hor/fdi:010060641 10.1094/mpmi-03-13-0076-r 0894-0282 [F B010060641] https://www.documentation.ird.fr/hor/fdi:010060641 https://www.documentation.ird.fr/intranet/publi/2013/10/010060641.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2013-11-04 2017-08-23 fdi:010060641 fre