Endophytic colonization of Arabidopsis thaliana by Gluconacetobacter diazotrophicus and its effect on plant growth promotion, plant physiology, and activation of plant defense

Abstract

Background and aims Gluconacetobacter diazotrophicus is a plant growth-promoting bacteria (PGPB) that colonizes several plant species. Here, we studied the internal colonization of Arabidopsis thaliana tissues by G. diazotrophicus and analyzed its effects on physiology, growth, and activation of plant immune system during such association.Methods A. thaliana seedlings were inoculated with G. diazotrophicus and grown in substrate for 50 days. Effects on plant growth were estimated by quantifying number of leaves, leaf area, and fresh and dry weight. Endophytic bacterial population was determined by colony-forming unit (CFU), and its location in plant tissues was assayed by epifluorescence microscopy of red fluorescent protein-labeled bacterium. Whole canopy gas exchange (photosynthesis and transpiration) was determined using a portable photosynthesis system. Results G. diazotrophicus efficiently promoted A. thaliana plant growth at 50 days after inoculation. Inoculated plants showed higher whole canopy photosynthesis, lower whole plant transpiration, and increased water-use efficiency. The bacterium colonized preferentially root xylem. The inoculation of plants defective in systemic acquired resistance (SAR)-associated defense revealed that plant immune system plays an important role during the early association stages. Conclusions G. diazotrophicus endophytically colonizes A. thaliana roots, promotes plant growth, and increases whole canopy photosynthesis. Our results indicate that A. thaliana is useful for molecular studies of the mechanisms involved in the interaction between plants and PGPB, especially those involving G. diazotrophicus.

Establishing symbiotic nitrogen fixation in cereals and other non-legume crops: The Greener Nitrogen Revolution

“…The dotted line indicates when the yield of the full recommended rate of N fertilizer* according to the total available N in the soil pre-sowing is equivalent to the yield of the NFix ® treatment only research that has been conducted in this field with Gd has involved the inoculation of Arabidopsis thaliana. In this study, Gd had beneficial effects on photosynthesis [90]. Whole-canopy photosynthesis levels were 68% higher in inoculated plants compared to uninoculated plants.…”

“…As a consequence of greater carbon uptake and lower water loss through transpiration, inoculated plants showed increases of 94.5% in whole-canopy water-use efficiency compared to non-inoculated plants. These results suggest that Gd positively affects plant physiology by increasing the photosynthetic capacity and improving water-use efficiency [90], which goes some way to explaining the parallel yield relationships across all levels of N fertilizers, shown in Figs. 1 and 2.…”

Non-nodular Endophytic Bacterial Symbiosis and the Nitrogen Fixation of Gluconacetobacter diazotrophicus

“…These techniques include chlorophyll levels and leaf percentage nitrogen [17], nitrogenase activity measured through an acetylene reduction assay (ARA) [136,137], nif gene mutant studies [138], labeled nitrogen 15 N2 studies [137][138], enhanced photosynthetic rates [16] and plant growth and yield benefits [12,19,139,140].…”

“…It has been demonstrated that strains of G. diazotrophicus differentially affected growth parameters of sugarcane, with some strains improving germination, tiller number and plant height relative to others [14] and there is also evidence that G. diazotrophicus improves tolerance to the sugarcane pathogen Xanthomonas albilineans as a result of production of bacteriocin; as well as reducing galling caused by root knot nematodes (Meloidogyne incognita) in bottle gourds and cotton [15]. G. diazotrophicus has also been shown to enhance photosynthetic capability and water use efficiency [16] and in sorghum increased chlorophyll and leaf nitrogen [17].…”

Essential role of K+ uptake permease (Kup) for resistance to sucrose‐induced stress in Gluconacetobacter diazotrophicus PAl 5

“…One of the most sugar-tolerant bacteria reported is Gluconacetobacter diazotrophicus, which can tolerate water activity as low as 0.892 when cultured under high sugar concentrations . G. diazotrophicus is an endophytic plant growth-promoting bacteria (PGPB) that was first isolated from sugarcane (Cavalcante and Dobereiner, 1988) and is able to promote plant growth when inoculated in several species (Vargas et al, 2014;Rangel de Souza et al, 2015;Sahai et al, 2015).…”