The main objective of this work was to analyze the effect of boron (B) deficiency on nodule organogenesis. Boron is an essential micronutrient for plants and for the Rhizobium-legume symbiosis development. Boron deficiency has a strong effect on components involved in plant-bacteria molecular and cell interactions during the development of the legume-rhizobia symbiosis. Because nodule organogenesis is driven by rhizobia-legume interactions, the effect of B deficiency on cell cycle regulation during nodule development was studied in Pisum sativum and Medicago sativa plants.

The rhizobia-legume symbiosis is driven by cell and molecular plant-microbe interactions that must work very accurately to avoid triggering of host plant defense reactions. Failure in cell or molecular components implicated in the interaction often results in pathogenic rather than symbiotic responses. Boron (B), a micronutrient essential for plant growth, seems to modulate signaling during nodule development. Boron deficiency alters early preinfection and invasion events, turning incompatible the interaction between the legume and its host rhizobio, and some plant defense mechanisms, including morphological barriers and synthesis of pathogenesis-related (PR) proteins take place.