Biology subjects

Wisniewski-Dye, F.

Publications and source records attributed to Wisniewski-Dye, F..

3 recordsLinked to original sources

bioRxiv2025

Extracellular vesicles of a phytobeneficial bacterium trigger distinct systemic response in plant

Bacterial extracellular vesicles (EVs) are lipidic shuttles that play roles in virulence, inter-species competition, and in the induction of the host immune response. While they have primarily been investigated in animal-bacteria interactions, knowledge regarding phytobacterial EVs remains limited. Recent findings revealed that various biotic factors like hydroxycinnamic acids can regulate EVs production. Hydroxycinnamic acids, such as ferulic acid, are lignin components abundantly released in the plant environment, where they impact the ecology of numerous phytobacteria. Azospirillum sp. B510, a phytobeneficial bacterium, induces the accumulation of hydroxycinnamic acid derivatives in the plant and can metabolize them as carbon sources. We hypothesized that the presence of ferulic acid in the environment of Azospirillum sp. B510 would influence its EVs production in terms of size, quantity, and cargo. Conversely, we also proposed that EVs from this phytobacterium would influence plant metabolites and defense gene expression. Our results show both that ferulic acid (mimicking the plant environment) influences the content of EVs released by Azospirillum sp. B510 and that bacterial EVs also impact plant physiology at a systemic level according to their cargoes. This research provides the first evidence of a global effect of bacterial EVs on the plant and highlights the dynamics of plant-bacteria interactions mediated by EVs.

microbiology↗

bioRxiv2023

Inhibition of broomrape germination by 2,4-diacetylphloroglucinol produced by environmental Pseudomonas.

Phloroglucinol compounds (PGCs) produced by environmental Pseudomonas are well known for their capacity to limit plant-pathogen infection. Although PGCs and more specifically 2,4-diacetylphloroglucinol (DAPG) are well studied for their antimicrobial properties, they are to some extent toxic for crop plants. Parasitic weeds such as broomrapes (Phelipanche ramosa and Orobanche cumana) cause severe damage to crops and their development must be controlled. Here, we assessed the potential herbicidal effect of the bacterial model Pseudomonas ogarae F113, a PGCs-producing bacterium, on parasitic weed germination. We show using a mutagenesis approach that PGCs produced in bacterial supernatants are the main determinant inhibiting the germination of broomrapes. The use of individual or cocktails of pure PGCs revealed that the inhibition of the germination depends on the PGCs molecular structure and their concentrations as well as the broomrape species and pathovars. Furthermore, the inhibition caused by the PGCs is irreversible, causing a brown coloration of the broomrape seeds. Then, we evaluated in non-sterile soils the ability of bacterial inoculants or chemical DAPG to limit the infection of broomrapes on oil seed rape. Only the inoculation of PGCs-producing bacteria limited the infection of P. ramosa. Moreover, elemental profiling analysis of oil seed rape revealed that neither the inoculant nor applied DAPG affected the nutrition capacity of the oil seed rape. Our study expands the knowledge on the role that these multi-talented plant-beneficial Pseudomonas play in the environment and open new avenues for the development of natural bioherbicides to ward off parasitic plant infection.

microbiology↗

bioRxiv2019

A novel plasmid-transcribed regulatory sRNA, QfsR, controls chromosomal polycistronic mRNAs in Agrobacterium tumefaciens

Plasmids are mobile DNAs that adjust host cell functions for their own amplification and dissemination. We identified QfsR, a small RNA, transcribed from the Ti plasmid in the phytopathogen Agrobacterium fabrum. QfsR is widely conserved throughout RepABC plasmids carried by Rhizobiaceae. Target prediction, expression analysis and site-direct mutagenesis experiments show that QfsR directly pairs within polycistronic mRNAs transcribed from chromosomes (involved in flagella apparatus and succinoglycan biosynthesis) and Ti plasmid (involved in conjugative transfer). QfsR leads to a coordinated expression of whole polycistronic mRNA molecules. Whereas a lack of QfsR induces motility and reduces succinoglycan production, its overproduction increases the quorum sensing signal accumulation and the Ti plasmid conjugative transfer. Based on these observations, we propose QfsR as a hub connecting regulatory networks of motility, succinoglycan biosynthesis and plasmid conjugative transfer. To our knowledge, QfsR is the first example of a plasmid-encoded sRNA that controls chromosomal polycistronic mRNAs. SignificancePlasmids represent an important cost for the hosting cell although some are beneficial under certain circumstances. Agrobacterium tumefaciens harboring Tumor inducing plasmid (pTi) are able to infect plants and to use specific resources produced by the infected cells. We characterized QfsR, a novel small RNA (sRNA) from pTi, that directly regulates plasmid polycistronic mRNA but also chromosomal ones. QfsR contributes to a fine-tuned regulation of bacterial motility, exopolysaccharide biosynthesis and conjugative dissemination of pTi. Our results report the first plasmid-encoded sRNA able to modify and coordinate cellular behaviour probably for the benefit of the plasmid dissemination and tight crosstalk between plasmid and chromosome. This could be widespread since QfsR homologs were predicted in other plasmids of Rhizobiaceae symbionts and pathogens.

genomics↗