Phosphate-Solubilizing Pseudomonas sp. Strain WS32 Rhizosphere Colonization-Induced Expression Changes in Wheat Roots

Abstract

Rhizosphere colonization is a pre-requisite for the favorable application of plant growth-promoting rhizobacteria (PGPR). Exchange and mutual recognition of signaling molecules occur frequently between plants and microbes. Here, the luciferase luxAB gene was electrotransformed into the phosphate-solubilizing strain Pseudomonas sp. WS32, a type of plant growth-promoting rhizobacterium with specific affinity for wheat. A labeled WS32 strain (WS32-L) was applied to determine the temporal and spatial traits of colonization within the wheat rhizosphere using rhizoboxes experimentation under natural condition. The effects of colonization on wheat root development and seedling growth were evaluated, and RNA sequencing (RNA-seq) was performed to explore the transcriptional changes that occur in wheat roots under WS32 colonization. The results showed that WS32-L could survive in the wheat rhizosphere for long periods and could expand into new zones following wheat root extension. Significant increases in seedling fresh and dry weight, root fresh and dry weight, root surface area, number of root tips, and phosphorus accumulation in the wheat leaves occurred in response to WS32 rhizosphere colonization. RNA-seq analysis showed that a total of 1485 genes in wheat roots were differentially expressed between the inoculated conditions and the uninoculated conditions. Most of the transcriptional changes occurred for genes annotated to the following functional categories: “phosphorus and other nutrient transport,” “hormone metabolism and organic acid secretion,” “flavonoid signal recognition,” “membrane transport,” and “transcription factor regulation.” These results are therefore valuable to future studies focused on the molecular mechanisms underlying the growth-promoting activities of PGPR on their host plants.

The potential of Pseudomonas fluorescens SBW25 to produce viscosin enhances wheat root colonization and shapes root-associated microbial communities in a plant genotype-dependent manner in soil systems

“…Despite the similar colonization potential of the two wheat cultivars observed for SBW25 WT and Δ viscA , respectively, SBW25 WT was found to also impact plant root architecture parameters dependent on plant genotype. It has previously been shown that inoculation of plants with plant-beneficial bacteria alters root morphology ( 66 – 68 ), but to our knowledge, this is the first time that it is shown to be cultivar-dependent. The observed differential effect on plant root parameters could be the result of differential community assembly, dependent both on plant genotype and/or the ability of the inoculant to produce viscosin.…”

The potential ofPseudomonas fluorescensSBW25 to produce viscosin enhances wheat root colonization and shapes root-associated microbial communities in a plant genotype dependent manner in soil systems

“…Despite the similar colonization potential of the two wheat cultivars observed for SBW25 and ∆viscA, respectively, viscosin was found to impact plant root architecture parameters dependent on plant genotype. It has previously been shown that inoculation of plants with plant beneficial bacteria alters root colonization [57,58,59], but to our knowledge this is the first time, that is has been shown to be cultivar-dependent. The observed differential effect on plant root parameters could be the result of differential community assembly, dependent both on plant genotype and/or the ability of the inoculant to produce viscosin.…”