The DMI3 gene of the model legume Medicago truncatula encodes a calcium and calmodulin dependent protein kinase (CCaMK) involved in the signalling pathways leading to the establishment of both mycorrhizal and rhizobial root symbiosis. The removal of the auto-inhibitory domain that negatively regulates the kinase activity in M. truncatula results in a constitutively-active form, inducing symbiotic responses in the absence of bacterial signals. In this study, we verified the functionality of a DMI3 variant and its ability to induce spontaneous nodules in M. truncatula dmi3 mutant. Our results based on enzymatic radio activity assay using [g-33P] ATP, suggests that the DMI3-311 variant is active and its corresponding gene (DMI3-311) when introduced in the dmi3 mutant, by Agrobacterium rhizogenes transformation, induced in the formation of a few spontaneous nodules.

 

Key words:  Medicago truncatula, CCaMK; DMI3 variant; spontaneous nodules.