Dynamics of Hydrogen Peroxide Accumulation During Tip Growth of Infection Thread in Nodules and Cell Differentiation in Pea (Pisum sativum L.) Symbiotic Nodules

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Abstract: Hydrogen peroxide (H2O2) in plants is produced in relatively large amounts and plays auniversal role in plant defense and physiological responses, including the regulation of growth anddevelopment. In the Rhizobiumlegume symbiosis, hydrogen peroxide plays an important signalingrole throughout the development of this interaction. In the functioning nodule, H2O2 has beenshown to be involved in bacterial differentiation into the symbiotic form and in nodule senescence.In this study, the pattern of H2O2 accumulation in pea (Pisum sativum L.) wild-type and mutantnodules blocked at different stages of the infection process was analyzed using a cytochemicalreaction with cerium chloride. The observed dynamics of H2O2 deposition in the infection threadwalls indicated that the distribution of H2O2 was apparently related to the stiffness of the infectionthread wall. The dynamics of H2O2 accumulation was traced, and its patterns in different nodulezones were determined in order to investigate the relationship of H2O2 localization and distributionwith the stages of symbiotic nodule development in P. sativum. The patterns of H2O2 localization indifferent zones of the indeterminate nodule have been partially confirmed by comparative analysison mutant genotypes.