Epsilon Archive for Student Projects

Abstract

Climate change has intensified the need for sustainable agricultural practices, particularly in managing drought stress, which significantly affects crop productivity. This study investigates the role of Plant Growth-Promoting Rhizobacteria (PGPR) in enhancing plant growth and drought tolerance, focusing on three bacterial strains: Pseudomonas salmasensis SLU99, Pseudomonas chlororaphis FG294, and Bacillus amyloliquefaciens PSE31B. We used confocal microscopy to investigate the colonization pattern of the PGPR strains. The study further explored the impact of PGPR on plant physiology under drought stress and their influence on phytohormonal pathways, particularly in Arabidopsis thaliana and tomato plants. Confocal microscopy confirmed that SLU99, FG294, and PSE31B colonize the outer tissue of roots and the vascular system. PGPR application during drought increased the photosynthetic efficiency and root biomass of inoculated tomatoes (Solanum lycopersicum). Similarly, we observed a significantly increased number of lateral roots in Arabidopsis thaliana Col-0 and mutant lines ein2, etr1-7, tir1, and abi1-1 when treated with PGPR. These results suggest that PGPR positively influence root growth, leading to increased water and nutrient uptake, especially under drought conditions. Inoculation of Col-0 with SLU99 upregulated the expression of Ethylene Response Factor1 (ERF1) and Weak Ethylene Insensitive (WEI2), indicating that SLU99 promotes auxin biosynthesis in an ethylene-dependent and independent manner. The upregulation of the stress-response gene ERF1 suggests the potential role of SLU99 in mediating abiotic stress tolerance. The findings highlight the beneficial role of PGPR in enhancing plant growth and drought tolerance, providing a promising avenue for sustainable agriculture.