Host-adaptive traits in the plant-colonizing Pseudomonas donghuensis P482 revealed by transcriptomic responses to exudates of tomato and maize

Abstract

Pseudomonads are metabolically flexible and can thrive on different plant hosts. However, the metabolic adaptations required for host promiscuity are unknown. Here, we addressed this knowledge gap by employing RNAseq and comparing transcriptomic responses of Pseudomonas donghuensis P482 to root exudates of two plant hosts: tomato and maize. Our main goal was to identify the differences and the common points between these two responses. Pathways upregulated only by tomato exudates included nitric oxide detoxification, repair of iron-sulfur clusters, respiration through the cyanide-insensitive cytochrome bd, and catabolism of amino and/or fatty acids. The first two indicate the presence of NO donors in the exudates of the test plants. Maize specifically induced the activity of MexE RND-type efflux pump and copper tolerance. Genes associated with motility were induced by maize but repressed by tomato. The shared response to exudates seemed to be affected both by compounds originating from the plants and those from their growth environment: arsenic resistance and bacterioferritin synthesis were upregulated, while sulfur assimilation, sensing of ferric citrate and/or other iron carriers, heme acquisition, and transport of polar amino acids were downregulated. Our results provide directions to explore mechanisms of host adaptation in plant-associated microorganisms.

Carbon source and surface type influence the early-stage biofilm formation by rhizosphere bacteriumPseudomonas donghuensisP482

“…Two plant models were chosen for the analyses of plant tissues colonization as a form of biofilm formation on biotic surface by the P482, that is tomato and maize, as the representatives of the dicots and monocots, respectively. P482 is a tomato rhizosphere isolate and it has been shown previously to efficiently colonize other plant species, including maize (Krzyzanowska et al, 2012;Krzyżanowska et al, 2023).…”

“…For various bacterial species it has been demonstrated that the root exudates and substances secreted by the plant cells also play role during establishment of microbiome on the host tissues (Danhorn and Fuqua, 2007;Rudrappa, Splaine, et al, 2008). In a recent work by Krzyżanowska and colleagues (Krzyżanowska et al, 2023) it has been demonstrated that P482 exhibits different patterns of gene expression in response to root exudates of the two plant hosts, tomato and maize. Induction of genes associated in P482 with motility, e.g.…”

“…The electron and atomic force microscopy observations demonstrated that the P482 cells are flagellated at one of the poles, what would enable the bacteria to move in the environment and possibly take part in cell attachment to various surfaces. Being a tomato rhizosphere isolate it was shown to colonize plant rhizosphere (Krzyzanowska et al, 2012) and respond adaptively to tomato and maize exudates (Krzyżanowska et al, 2023). Up to date, no data was available on the determinants of biofilm formation on biotic or abiotic surfaces by P. donghuensis P482 or any of its three sister strains (i.e.…”