Functional characterization of the PhoB/PhoR two-component system in the regulation of phosphorus solubilization and mineralization by Pantoea agglomerans 33.1.

Abstract

Phosphorus (P) is an essential element for plant development. It is an important component in the formation of membranes, adenosine triphosphate, and nucleic acids. However, few amount of the phosphorus present in soils is available to plants. It is only absorb as soluble anionic forms, corresponding to approximately 0.1% of the total present in the soil. Although the use of phosphate fertilizers increases crop productivity, they are extracted from non-renewable sources and cause serious environmental and ecological problems. Plant growth-promoting bacteria (PGPB) are considered a promising alternative to this problem, as they are capable of increasing the availability of phosphorus for plant absorption. In this context, bacteria of the species Pantoea agglomerans stand out, which have already been reported as plant growth promoters and with the ability to solubilize/mineralize nutrients. The P. agglomerans 33.1 strain has been widely studied and has shown great potential as a growth promoter, P solubilizer, exopolysaccharide, and biofilm producer. In its genome, genes related to phosphate mineralization and solubilization have already been identified, such as phoB and phoR, belonging to the Two Component System (TCS). The TCS is responsible for regulating the expression of several other genes through the perception of environmental P, generating specific signaling depending on its availability in the medium. Thus, this project aims to characterize the PhoB/PhoR TCS and its participation in the regulation of other genes related to phosphate solubilization, mineralization, absorption, and transport through the knockout of the phoB and phoR genes via CRISPR-Cas9. The understanding of gene regulation according to the availability of P to plants is important for the development of more sustainable technologies and management related to the use of mineral fertilizers.