Identification of Pisum sativum L. cytokinin and auxin metabolic and signaling genes, and an analysis of their role in symbiotic nodule development

The present work was designed to study the role of the phytohormones, cytokinin and auxin, in the symbiosis development between pea Pisum sativum L. and Rhizobium leguminosarum bv. viciae. To achieve this aim, the temporal expression patterns of the genes related to the cytokinin and auxin biosynthesis, perception, and response were studied. It was found that most of these genes showed specific transcriptional regulations upon nodulation at various stages following inoculation. Once they were purified using chromatographic methods, the endogenous cytokinins were detected by liquid chromatography-electrospray tandem mass spectrometry (LC[+]ES–MS). Our findings showed that cytokinin and auxin accumulation is tightly regulated during nodulation in order to control nodule organogenesis, infection events, and nodule function. Key words: Legume-Rhizobium symbiosis, cytokinin, auxin, gene expression.