A Proteomic Approach Suggests Unbalanced Proteasome Functioning Induced by the Growth-Promoting Bacterium Kosakonia radicincitans in Arabidopsis

Abstract

Endophytic plant growth-promoting bacteria have significant impact on the plant physiology and understanding this interaction at the molecular level is of particular interest to support crop productivity and sustainable production systems. We used a proteomics approach to investigate the molecular mechanisms underlying plant growth promotion in the interaction of Kosakonia radicincitans DSM 16656 with Arabidopsis thaliana. Four weeks after the inoculation, the proteome of roots from inoculated and control plants was compared using two-dimensional gel electrophoresis and differentially abundant protein spots were identified by liquid chromatography tandem mass spectrometry. Twelve protein spots were responsive to the inoculation, with the majority of them being related to cellular stress reactions. The protein expression of 20S proteasome alpha-3 subunit was increased by the presence of K. radicincitans. Determination of proteasome activity and immuno blotting analysis for ubiquitinated proteins revealed that endophytic colonization interferes with ubiquitin-dependent protein degradation. Inoculation of rpn12a, defective in a 26S proteasome regulatory particle, enhanced the growth-promoting effect. This indicates that the plant proteasome, besides being a known target for plant pathogenic bacteria, is involved in the establishment of beneficial interactions of microorganisms with plants.

Sugarcane pre-sprouted seedlings produced with beneficial bacteria and arbuscular mycorrhizal fungi

“…According to Jacoby (2017), these results can be associated with the beneficial characteristics of the bacterial strain, such as nifH amplification, suggesting that BNF can be associated with plant growth promotion and the mineralization and absorption of macronutrients (N, P and S). The nutritional status of plants is often associated with an increase in root growth caused by bacteria (Witzel et al 2017), which occurred in the present experiment. These beneficial microorganisms, commonly referred to as biofertilizers, which include bacteria and fungi, increase the plant ability to absorb nutrients; therefore, they are used as a complement to mineral fertilization, consequently resulting in shoot and root biomass increasing (Calvo et al 2014).…”

The Endophytic Microbiome as a Hotspot of Synergistic Interactions, with Prospects of Plant Growth Promotion

“…Proteome analysis of Kosakonia radicincitans DSM 16656 inoculated Arabidopsis thaliana revealed 12 protein spots responsive to cellular stress reactions, and inoculation of DSM 16656 increased the expression of 20S proteasome alpha-3-subunit. Endophytic colonization was inhibited by the accumulation of ubiquitin-dependent proteins and their degradation and as a result, it showed a decline in proteasome activity, however, inoculation A. thaliana mutant (rpn12a) defective in 26S proteasome was found to enhance the plant growth [ 237 ]. Inoculation of Sinorhizobium meliloti in rice showed upregulation of plant defense-related proteins in roots and photosynthesis-related proteins in aerial tissues [ 238 ].…”

Colonization of the tsetse fly midgut with commensal Kosakonia cowanii Zambiae inhibits trypanosome infection establishment

“…This outcome implies that Kco_Z modulates trypanosome infection outcomes in tsetse via a mechanism other than ROI production. Members of the genus Kosakonia [33–35], as well as several enteric commensals including Enterobacter spp. [36–38], produce organic acids, and these products can inhibit pathogen growth by creating an acidic environment [39,40].…”