Abstract
In the current study, we aimed to elucidate the plant growth-promoting characteristics of Pseudomonas psychrotolerans CS51 under heavy metal stress conditions (Zn, Cu, and Cd) and determine the genetic makeup of the CS51 genome using the single-molecule real-time (SMRT) sequencing technology of Pacific Biosciences. The results revealed that inoculation with CS51 induced endogenous indole-3-acetic acid (IAA) and gibberellins (GAs), which significantly enhanced cucumber growth (root shoot length) and increased the heavy metal tolerance of cucumber plants. Moreover, genomic analysis revealed that the CS51 genome consisted of a circular chromosome of 5,364,174 base pairs with an average G+C content of 64.71%. There were around 4774 predicted protein-coding sequences (CDSs) in 4859 genes, 15 rRNA genes, and 67 tRNA genes. Around 3950 protein-coding genes with function prediction and 733 genes without function prediction were identified. Furthermore, functional analyses predicted that the CS51 genome could encode genes required for auxin biosynthesis, nitrate and nitrite ammonification, the phosphate-specific transport system, and the sulfate transport system, which are beneficial for plant growth promotion. The heavy metal resistance of CS51 was confirmed by the presence of genes responsible for cobalt-zinc-cadmium resistance, nickel transport, and copper homeostasis in the CS51 genome. The extrapolation of the curve showed that the core genome contained a minimum of 2122 genes (95% confidence interval = 2034.24 to 2080.215). Our findings indicated that the genome sequence of CS51 may be used as an eco-friendly bioresource to promote plant growth in heavy metal-contaminated areas.
Highlights
Heavy metal stress greatly decreases crop growth and productivity
Various genera of Plant growth-promoting rhizobacteria (PGPR) including Pseudomonas, Bacillus, Rhizobium, Pantoea, Burkholderia, Paenibacillus, Enterobacter, Azospirillum, Achromobacter, Methylobacterium, Variovorax, and Microbacterium have been found to play a role in tolerance to abiotic stress [13,14]
We investigated the CS51 whole genome sequence to determine plant growth-promoting characteristics of P. psychrotolerans
Summary
Heavy metal stress greatly decreases crop growth and productivity. It is known as a major threat in various terrestrial ecosystems worldwide [1]. Extensive industrialization directly increases the accumulation of heavy metals in soils, which has detrimental effects on crop growth and productivity [2]. Plant growth-promoting rhizobacteria (PGPR) are a group of bacteria that can improve plant growth and productivity [8]. These microorganisms are found predominantly in the rhizosphere. Several genera of heavy metal-tolerant bacteria, including Pseudomonas, Bacillus, Methylobacterium, and Streptomyces have the ability to increase the growth and production of crops by minimizing the negative effects of heavy metal stress [12]. Various genera of PGPR including Pseudomonas, Bacillus, Rhizobium, Pantoea, Burkholderia, Paenibacillus, Enterobacter, Azospirillum, Achromobacter, Methylobacterium, Variovorax, and Microbacterium have been found to play a role in tolerance to abiotic stress [13,14]
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