In contrast to Rhizobium johnstonii strain 3841, R. johnstonii strain NaPi is able to form large pink nodules on the roots of pea (Pisum sativum L.) mutants in the gene Sym40. The genetic determinants underlying such efficiency have not been discovered yet. In this study, we report the complete genome sequence of the strain NaPi.

Hydrogen peroxide (H2O2) 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 Rhizobium–legume symbiosis, hydrogen peroxide plays an important signaling role throughout the development of this interaction. In the functioning nodule, H2O2 has been shown 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 mutant nodules blocked at different stages of the infection process was analyzed using a cytochemical reaction with cerium chloride. The observed dynamics of H2O2 deposition in the infection thread walls indicated that the distribution of H2O2 was apparently related to the stiffness of the infection thread wall. The dynamics of H2O2 accumulation was traced, and its patterns in different nodule zones were determined in order to investigate the relationship of H2O2 localization and distribution with the stages of symbiotic nodule development in P. sativum. The patterns of H2O2 localization in different zones of the indeterminate nodule have been partially confirmed by comparative analysis on mutant genotypes.

Rhizobium laguerreae is regarded as a promising candidate for biofertilization of legume plants worldwide through its high efficiency in symbiosis. In this paper, we report high-quality sequences of six R. laguerreae strains with total genome completeness from 93.5% to 97.5%.