P-422 - Pseudomonas N122 alters plant root architecture and improves drought tolerance

Plants employ various adaptive mechanisms to cope with water scarcity, balancing survival and growth. Under drought conditions, they may enhance root growth and regulate water loss through stomatal closure. While these strategies improve drought stress resilience, they often come at the expense of overall growth and yield potential. Recent studies have highlighted the functional potential of plant-associated bacteria to enhance drought tolerance in plants while minimizing associated trade-offs. Here, we screened over 100 bacterial strains isolated from roots of Carex arenaria (sand sedge) to assess their ability to promote drought tolerance across diverse plant species. Our comprehensive screening encompassed both soil and in vitro assays using plates supplemented with polyethylene glycol as a drought stress proxy. One of these strains, taxonomically delineated as Pseudomonas sp. N122 (PsN122), significantly alleviated drought stress in Arabidopsis, tomato, and wheat with minimal impact on their growth. We found that PsN122 alters the root architecture of Arabidopsis, resulting in an increased number of lateral roots and enhanced root hair formation. A time-course transcriptomic analysis in Arabidopsis identified early responsive plant genes that could mediate the effects of PsN122. Collectively, our results highlight the largely unexplored functional potential of plant-associated bacteria in alleviating abiotic stress across diverse plant species.