Diversidad bacteriana en rizosferas de Atriplex lampa tratados con PGPR

Abstract

Atriplex lampa is a valuable shrub from Patagonia. We isolated plant growth-promoting rhizobacteria (PGPR) from its rhizosphere in steppe soils (PS) and coastal dunes (Du) and assessed their effects on plant growth and rhizobacterial community. PGPR isolates produced ammonia, indoleacetic acid, and solubilized phosphorus. Du strains were affiliated with salt-tolerant Stutzerimonas and Halomonas, while PS strains included Bacilli and Actinomycetes. Stutzerimonas sp. 5A and Pseudarthrobacter sp. 15 inoculation significantly increased plant height and biomass, whereas Bacillus sp. 48 had no effects. The rhizobacterial community structures changed after inoculation, while their diversity remained unaffected. Nitrogen-fixing and growth-promoting families (Azospirillaceae, Beijerinckiaceae, and Pseudomonadaceae) increased in roots inoculated with 5A and 15. Near full-length 16S rRNA gene sequences of each isolate (5A, 15, and 48) were used to identify their corresponding OTUs within the V4 region amplicon dataset. The absence of significant differences in such OTU abundances among treatments indicated that inoculation triggered taxonomic shifts rather than promoting their own enrichment. Our results not only confirm the biotechnological potential of strains 5A and 15 but also provide the novel insight that PGPR can promote native dryland plant growth by reshaping the rhizosphere bacterial community structure, rather than solely through enhancing their own proliferation.