Whole-Genome Sequence Insight into the Plant-Growth-Promoting Bacterium Priestia filamentosa Strain AZC66 Obtained from Zygophyllum coccineum Rhizosphere.

Abstract

This study aimed to isolate, screen the plant-growth-enhancing features, and explore the whole-genome sequence of AZC66 isolated from the rhizosphere of Zygophyllum coccineum and determine its biostimulating effects on the growth of cowpea under greenhouse conditions. Salkowski reagent was used to measure AZC66's indole acetic acid production. AZC66's inorganic phosphate solubility on Pikovskaya agar was evaluated using tricalcium phosphate. The results indicated the ability of AZC66 to fix nitrogen, produce IAA (66.33 ± 0.44 μg mL-1), solubilize inorganic phosphate, and exhibit the activity of ACC deaminase (278.40 ± 21 mol -ketobutyrate mg-1 h-1). Cowpea's root and shoot dry weights were also significantly increased after in vitro inoculation with AZC66. The identity of AZC66 was confirmed as Priestia filamentosa, and 4840 genes were predicted in its genome. The gene sequences were compared against the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, and the results showed that the top three pathways wherein the maximum number of genes are involved are signaling and cellular processes, genetic information processing, and carbohydrate metabolism. The genome sequencing of the strain AZC66 revealed a number of genes implicated in plant biostimulation activities such as nitrogen fixation (nifU), phytohormone synthesis (trpAB genes), phosphate solubilization (PhbCEF, pstABCS, and phoU), and siderophore formation (FbpA, feoAB, and fetB). The AZC66 genome contained numerous genes involved in nitrogen metabolism, nitrogen regulation, and the nitrate reduction pathway. The phenazine biosynthetic gene in AZC66 demonstrated biocontrol and soil survival properties. The trehalose synthesis genes in AZC66 may help plants resist osmotic and salt stress. The discovery of glycine betaine, cold shock, and heat shock protein genes demonstrated that AZC66 could withstand harsh conditions. AZC66 might be used to create robust, sustainable biological fertilizers for future agricultural use in Saudi Arabia. Furthermore, the predicted adaptable metabolic pathways might serve as the basis for potential biotechnological applications in agriculture and industry.