Endophytic Colonization of tomato plants by Gluconacetobacter diazotrophicus and its effect on crops improvement and yield promotion

Gluconacetobacter diazotrophicus (G.d) is a nitrogen-fixing, endophyticand non-nodulating bacterium isolated from sugarcane. The aim of thisstudy was to investigate the effect of different G.d concentrations ontomato plants grown at very low nitrogen levels to examine its ability tocolonize plant tissues and improve crop yield. Tomato seeds wereinoculated with different doses of G.d (109, 1010, and 1011 CFU/ml) andgrown in the glasshouse under nitrogen deficiency conditions. Estimationof endophytic bacterial population was performed by bio-PCRs analysisusing specific primers for G.d. Three months after sowing, significantvariations in the phenotypes and biomass production were observed: theinoculated plants with 1010 and 1011 of G.d-Nfix-3%sucrose showedincreased plant height, root length, nitrogen content, and flower number.They also exhibited a healthier phenotype and higher fruit production incomparison to 109 of G.d-Nfix-3%sucrose and non-inoculated controlplants. These results showed that coating tomato seeds with specificconcentrations of G.d-Nfix-3%sucrose (1010 and 1011 CFU/ml) was aneffective enhancer for crop production at low nitrogen levels and provedthe ability of G.d to enhance production of tomato fruits. In conclusion,this study aimed to develop a natural nitrogen fixing seed coatingtechnology to provide a sustainable solution to fertilizer overuse andnitrogen pollution. This technology is environmentally friendly because itbased on a food-grade bacterium (G.d) derived from sugarcane. It aims toaddress the need of international market for sustainable agriculturalfertilizers. Moreover, it provides a cost benefit to the farmers via reducedfertilizer costs and improved crops yields.