Genotypic and Phenotypic Characterization of Pseudomonas atacamensis EMP42 a PGPR Strain Obtained from the Rhizosphere of Echinocactus platyacanthus (Sweet Barrel)

TL;DR

This paper characterizes a new strain of Pseudomonas atacamensis, EMP42, found in cactus roots, showing its plant growth-promoting abilities and genetic features.

Contribution

The study provides a detailed genomic and phenotypic characterization of a novel P. atacamensis strain with potential agricultural applications.

Findings

Strain EMP42 improves plant growth and seedling survival in multiple species.

The genome of EMP42 includes genes linked to plant growth promotion and stress reduction.

EMP42 shows phylogenomic similarity to the reference P. atacamensis strain B21-026.

Abstract

Plant growth-promoting rhizobacteria (PGPR) are a group of bacteria that associate with the rhizosphere of plants; one of the most abundant bacterial genera in this ecological niche is Pseudomonas, which is constantly expanding due to the emergence of new species such as Pseudomonas atacamensis, whose discovery in 2019 has led to the characterization of several strains from different environments but taxonomically related. The objective of this work was to phenotypically and molecularly characterize P. atacamensis strain EMP42, isolated from the rhizosphere of Echinocactus platyacanthus. The strain EMP42 is able to use different substrates and reduce oxidative stress in plants. It is capable of improving growth parameters such as the number of inflorescences and the height of the aerial body of Arabidopsis thaliana, as well as the germination and seedling survival of the cacti Echinocactus platyacanthus and Astrophytum capricorne. The genetic structure of P. atacamensis EMP42 consists of a closed chromosome of 6.14 Mbp, and 61.1% GC content. It has 5572 genes, including those associated with PGPR activities, such as the trpABCDE, SAP, phoABPRU and acsABC genes, among others, and three ncRNA loci, nine regulatory regions, five complete rRNA operons and three CRISPR-Cas loci, showing phylogenomic similarities with the reference strain P. atacamensis B21-026. Therefore, this study contributes to the understanding of genomic diversity within P. atacamensis and, particularly, highlights the potential application of strain EMP42 as a PGPR.

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