Two‐component system in Rahnella aquatilis is impacted by the hyphosphere of the arbuscular mycorrhizal fungus Rhizophagus irregularis

Abstract

Summary Two‐component systems (TCS) are ubiquitous among bacteria, playing key roles in signalling events. However, to what extent the TCS of Rahnella aquatilis (a Phosphate solubilizing bacteria) is influenced by the hyphosphere of the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis is totally unknown. Here, the expression of 16 genes encoding the TCS of R. aquatilis (i.e. involved in carbon‐sensing and nutrient‐sensing) and of eight genes regulated by the PhoR TCS (i.e. involved in inorganic and organic phosphorus mobilization) were analysed at regular intervals in presence of hyphae of R. irregularis. The study was conducted under in vitro culture conditions with phytate as the unique source of phosphorus. In presence of the AM fungus, the expression of TCS genes involved in carbon‐sensing and nutrient‐sensing were stimulated. Only, BaeS at 30 and 120 min, and BaeR at 60 min were inhibited. In addition, the PhoR TCS stimulated the expression of genes encoding phosphatase but inhibited the expression of genes involved in gluconic acid production. As the mechanism of coupling environmental changes with cellular physiological changes, TCS plays a pivotal role in regulating specific gene expression in R. aquatilis, recognizing environmental signals. More importantly, TCS genes may regulate bacteria response to hyphal carbon to mobilize phosphorus efficiently in the hyphosphere.

Strip intercropping with local crops increased Aconitum carmichaeli yield and soil quality

“…In the two intercropping systems, the potential functions of 28 potential beneficial genera included the following: the generation of IAA (Bal et al, 2013), nitrogen fixation (Hayat et al, 2010;Shahrajabian et al, 2021), soil mercury content reduction (Ustiatik et al, 2022), the degradation of polycyclic aromatic hydrocarbons (Zhao et al, 2021), antibacterial functions (Mosquera et al, 2020), antimycotic functions (De Brito et al, 2022), aluminum tolerance (Silambarasan et al, 2022), salt and alkali resistance , phosphate solubilization (Chhetri et al, 2021;Saadouli et al, 2021), siderophores (Jamalzadeh et al, 2021;Nie et al, 2022), nitrification (Peng et al, 2021), etc. In the control group, the potential functions of the 15 potentially beneficial genera were as follows: the nitrogen cycle (Zhang et al, 2022), antibiotic functions (Nakkeeran et al, 2021), heavy metal resistance (Zhai et al, 2020;Sharma et al, 2022), phosphate solubilization (Huang et al, 2021;Duan et al, 2022), improved photosynthesis (Katsenios et al, 2021), nitrification (Li et al, 2022), etc. Six of the harmful genera were pathogens (Liu et al, 2020b;Na et al, 2021;Tancos et al, 2021;Kaari et al, 2022;Patane et al, 2022).…”

AM fungal-bacterial relationships: what can they tell us about ecosystem sustainability and soil functioning?

“…Rhizosphere bacteria have been known to synthesize their own secondary metabolites for microbial communications including anti-fungal, anti-bacterial, pigments that provide protection, and siderophores involved in scavenging iron ( Turrini et al., 2018 ; Dror et al., 2020 ; Pang et al., 2021 ). While the role of AM fungi in these processes have yet to be elucidated, it is evident that AM fungi indirectly influence functions in host plants (like plant metabolite production) and have been thought to mimic quorum sensing in bacteria ( Zhang et al., 2018b ; Emmett et al., 2021 ; Duan et al., 2022 ). Nonetheless, AM fungi’s high biomass in most soil environments lend to ecological advantages that increase their interactions with organisms both within and outside the rhizosphere.…”

Hyphosphere interactions between Rhizophagus irregularis and Rahnella aquatilis promote carbon–phosphorus exchange at the peri‐arbuscular space in Medicago truncatula

“…Indeed, various bacteria have been found to colonize the surface of AM fungal hyphae to access hyphal exudates (Emmett et al, 2021; Scheublin et al, 2010). Over the last decade, substantial progress has been made in comprehending these interactions in the hyphosphere (Duan et al, 2022; Jiang et al, 2021; Zhang et al, 2014, 2018), the most prominent one being between the AM fungus Rhizophagus irregularis and the phosphate‐solubilizing bacterium (PSB) Rahnella aquatilis . The hyphal exudates of the AM fungus were found to represent both a source of C for the bacterium as well as signalling and effector molecules stimulating bacterial growth and activity (Zeng et al, 2018; Zhang et al, 2016, 2018).…”