Gluconacetobacter diazotrophicus mitigates drought stress in Oryza sativa L.

Abstract

Background and aims: Plant growth promoting bacteria (PGPB) are associated with plant roots and augment plant productivity and immunity; however, recent work by several groups has shown that PGPB also elicit the so-called “induced systemic tolerance” to drought stress. This work aimed to evaluate the effect of Gluconacetobacter diazotrophicus Pal5 inoculation on the mitigation of drought stress in red rice (Oryza sativa L.). Methods: The experiment treatments of the red rice cultivar inoculated and uninoculated with G. diazotrophicus, and cultivated with and without water restriction. Physiological, biochemical, and molecular analyses of plant tissues were carried out, along with measurements of biomass and seed yield components. Results: The plants showed a positive response to inoculation with G. diazotrophicus, with promotion of growth and induction of tolerance to drought. Increase in plant biomass and higher levels of gas exchange and osmoprotectant solutes were observed in shoots. The bacterial inoculation increased the yield and positively regulated some defense genes against the water deficit in plants. Conclusions: G. diazotrophicus Pal5 strain inoculation was beneficial for red rice plants, suppressing the various deleterious effects of drought stress and increasing the biomass and seed yield components.