Physiological and Genetic Modifications Induced by Plant-Growth-Promoting Rhizobacteria (PGPR) in Tomato Plants under Moderate Water Stress

Physiological, metabolic, and genetic changes produced by two plant growth promoting rhizobacteria (PGPR) Pseudomonas sp. (internal code of the laboratory: N 5.12 21.24) inoculated in tomato plants subjected to moderate water stress (10% polyethylene glycol-6000; PEG) were studied. Photosynthesis efficiency, photosynthetic pigments, compatible osmolytes, reactive oxygen species (ROS) scavenging enzymes activities, oxidative level expression genes related abscisic acid synthesis (ABA; 9-cis-epoxycarotenoid dioxygenase NCDE1 gene), proline (Pyrroline-5-carboxylate synthase P5CS plasma membrane ATPase (PM gene) measured. Photosynthetic efficiency was compromised PEG, but bacterial-inoculated reversed effects: while N5.12 increased carbon fixation (37.5%) maintaining transpiration, N21.24 both (14.2% 31%), negatively affecting stomatal closure, despite enhanced genes, evidencing activation different adaptive mechanisms. Among all parameters evaluated, pigments antioxidant guaiacol peroxidase (GPX) ascorbate (APX) responded differently strains. (70% chlorophyll a, 69% b, 65% carotenoids), (33%), glycine betaine (4.3%), phenolic compounds (21.5%) a greater extent, thereby decreasing (12.5% Malondialdehyde, MDA). Both bacteria have highly beneficial effects on stress, improving their physiological state. The use these agricultural production systems could reduce amount for irrigation without having negative impact food production.