Pantoea agglomerans FAP10: A novel biofilm-producing PGPR strain improves wheat growth and soil resilience under salinity stress

Abstract

Salinity is among the major environmental factors affecting performance of both crop plants and soil bacterial inoculants beneficial to plant growth. Based on previous screening studies, a novel halotolerant biofilm-forming PGPR strain, namely Pantoea agglomerans-FAP10, was studied for its potential to protect wheat (Triticum aestivum; var. 343) against salinity stress. The ability of this strain to produce biofilms on glass surfaces, 96 well microtiter plates and seedling roots was characterized qualitatively and quantitatively using light and scanning electron microscopy (SEM). The FAP10 strain was tested for performance by inoculating on wheat in a pot-soil system under varied salinity stresses (75, 125, 250 and 500mM NaCl). The FAP10 strain exhibited discrete and multifarious plant growth-promoting traits as well as efficient rhizosphere and root colonization which could sustain wheat growth under salinity stress. The FAP10-induced modifications conferred enhanced plant salinity tolerance by regulating photosynthetic attributes (gs, Ci, E, iWUE, PN, PSII, and Rubisco enzyme activity), antioxidant system (SOD, CAT, GR, APX, GSH, MDA, and proline), and sulfur metabolism (sulfur and cysteine content, ATP-S, and SAT activity), and also sustained soil physicochemical characteristics and hydrolytic enzymes including urease, protease, DHA, ALP, ACP and β glucosidase. The findings of the current study can support future efforts to improve plant salinity tolerance by engineering rhizobacterial biofilms and exploiting the potential of native strains for agricultural applications in stressed environments.