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

Hydrogen peroxide (HO) in plants is produced in relatively large amounts and plays a universal role in plant defense and physiological responses, including the regulation of growth and development. In the -legume symbiosis, hydrogen peroxide plays an important signaling role throughout the development of this interaction. In the functioning nodule, HO has been shown to be involved in bacterial differentiation into the symbiotic form and in nodule senescence. In this study, the pattern of HO accumulation in pea ( L.) wild-type and mutant nodules blocked at different stages of the infection process was analyzed using a cytochemical reaction with cerium chloride. The observed dynamics of HO deposition in the infection thread walls indicated that the distribution of HO was apparently related to the stiffness of the infection thread wall. The dynamics of HO accumulation was traced, and its patterns in different nodule zones were determined in order to investigate the relationship of HO localization and distribution with the stages of symbiotic nodule development in . The patterns of HO localization in different zones of the indeterminate nodule have been partially confirmed by comparative analysis on mutant genotypes.