Arabidopsis interaction with beneficial pseudomonas strains that confer tolerance to drought stress and promote root development

LLAMEDO, IGNACIO; CHAÍN, JOSE MARÍA; GUDESBLAT, GUSTAVO; AMODEO, GABRIELA; BAROLI, IRENE

ROSARIO

Congreso; XXXIV Argentinian Meeting of Plant Physiology (RAFV 23); 2023

SOCIEDAD ARGENTINA DE FISIOLOGÍA VEGETAL

ARABIDOPSIS INTERACTION WITH BENEFICIAL PSEUDOMONAS STRAINS THAT CONFER TOLERANCE TO DROUGHT STRESS AND PROMOTE ROOT DEVELOPMENTLLAMEDO, Ignacio1; CHAÍN, José María1; GUDESBLAT, Gustavo2, AMODEO, Gabriela1, BAROLI Irene1 1 Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA, UBA-CONICET) & Departamento de Biodiversidad y Biología Experimental (DBBE, FCEyN-UBA).2 Instituto de Biociencias, Biotecnología y Biología Translacional (IB3) & Departamento de Fisiología, Biología Molecular y Celular “Dr. Héctor Maldonado” (DFBMC, FCEyN-UBA).Within the global climate context, where plants face diverse environmental stresses, particularly water deficit, the application of growth-promoting bacteria (PGPB) stands out as a sustainable strategy to improve stress tolerance. PGPB can be found in the soil microbiota or in the phyllosphere, where they can stimulate the host plant growth and development, aid in nutrient uptake or enhance pathogen resistance. Some PGPB release phytohormone analogues or modify hormone signaling pathways in the host plant. Our group has found that two Pseudomonas strains isolated from agro-environments in Buenos Aires province, called M25 (originally described in [1]) and N33[2], promote drought tolerance in eucalyptus seedlings by enhancing water management through changes in stomatal conductance and cell wall elasticity[2]. We also showed that the strains exert their action from the rhizosphere, without colonizing plant tissues. These results prompted us to switch to arabidopsis as an amenable system where to investigate the mechanism of action of the bacteria at the root level. When plants were grown on agar plates, inoculation with M25 or N33 promoted changes in primary root length and lateral root number, each strain eliciting phenotypes different from each other and from control seedlings. Both strains produced a remarkable increase in the number and length of root hairs on primary roots. We used an arabidopsis line carrying the auxin-inducible DR5 promoter fused to GFP to analyze the participation of auxins in the bacteria-induced changes in root architecture. Compared with the control, we did not detect significant differences in the number of green fluorescent nuclei in inoculated root apices. These results indicate that arabidopsis is a suitable model to further study the mechanisms by which N33 and M25 bring about changes in root architecture and tolerance to drought.[1] Castagno et al. (2011) J. Appl. Microbiol. 110: 1151–1165[2] Chaín et al. (2020), Sci. Rep. 10: 1–17