Arabidopsis thaliana exudates induce growth and proteomic changes in Gluconacetobacter diazotrophicus

Abstract

Background Plants interact with a variety of microorganisms during their life cycle, among which beneficial bacteria deserve special attention. Gluconacetobacter diazotrophicus is a beneficial bacterium able to fix nitrogen and promote plant growth. Despite its biotechnological potential, the mechanisms regulating the interaction between G. diazotrophicus and host plants remain unclear. Methods We analyzed the response of G. diazotrophicus to cocultivation with Arabidopsis thaliana seedlings. Bacterial growth in response to cocultivation and plant exudates was analyzed. Through comparative proteomic analysis, G. diazotrophicus proteins regulated during cocultivation were investigated. Finally, the role of some up-accumulated proteins in the response G. diazotrophicus to cocultivation was analyzed by reverse genetics, using insertion mutants. Results Our results revealed the induction of bacterial growth in response to cocultivation. Comparative proteomic analysis identified 450 bacterial proteins, with 39 up-accumulated, and 12 down-accumulated in response to cocultivation. Among the up-accumulated pathways, the metabolism of pentoses and protein synthesis were highlighted. Proteins potentially relevant to bacterial growth response such as ABC-F-Etta, ClpX, Zwf, MetE, AcnA, IlvC, and AccC were also increased. Reverse genetics analysis, using insertion mutants, revealed that the lack of ABC-F-Etta and AccC proteins severely affects G. diazotrophicus response to cocultivation. Our data demonstrated that specific mechanisms are activated in the bacterial response to plant exudates, indicating the essential role of “ribosomal activity” and “fatty acid biosynthesis” in such a process. This is the first study to demonstrate the participation of EttA and AccC proteins in plant-bacteria interactions, and open new perspectives for understanding the initial steps of such associations.

Individual competence predominates over host nutritional status in Arabidopsis root exudate-mediated bacterial enrichment in a combination of four Burkholderiaceae species

“…The differences observed in growth on PRE for the four species can be explained because PRE produces the proliferation or decrease of certain microorganisms in the rhizospheric environment due, among other effects, to a co-adaptation process [27,28], resulting from a dynamic and complex environment where better-adapted microorganisms could grow [5,28]. Results recently published by dos Santos et al [29] confirm this idea. They reported that not only stimulation of certain metabolic pathways is observed in Gluconacetobacter diazotrophicus when is co-cultivated with Arabidopsis, but also that Arabidopsis constitutively exudates compounds that facilitate the plant-bacteria interaction.…”

Fungi-Bacteria Associations in Wilt Diseased Rhizosphere and Endosphere by Interdomain Ecological Network Analysis

“…It is possible they are opportunists that took advantage of the potential niche opened by pathogen invasion and entered the plant endophytic compartment (Lundberg et al, 2012). The compositional changes of these fungal communities may be caused by changes in root exudates or complex changes in the plant immune system during pathogen invasion (Martinoia and Baetz, 2014;dos Santos et al, 2020), and this promoted the differential recruitment and/or differential rejection of microorganisms to resist the invasion of bacterial wilt pathogen in plant roots and stems (Kwak et al, 2018). Microbe-microbe associations are essential for the function of microecosystems in soil and endophytic compartments (Barberán et al, 2012).…”