Presentation: 2025 ND EPSCoR Annual conference 

October 21, 2025, NDSU Memorial Union, Fargo, North Dakota

Synergistic effects of Azospirillum brasilense Sp7, seedling exudates, and cytidine on drought tolerance in pea plants

Drought stress is a major constraint to pea (Pisum sativum) production, reducing shoot vigor and root development. We hypothesized that adding the beneficial bacterium Azospirillum brasilense Sp7 together with pea seedling exudates and cytidine would help peas stay healthier during drought stress. Pea seedlings were germinated with or without exudates (1 mg/mL) and cytidine (0.1 M), then transplanted into sand–vermiculite medium with or without A. brasilense (10⁴ CFU/mL). After four weeks in greenhouse conditions, drought was imposed for nine days. Shoot health was scored daily based on percent wilting, leaf shrinkage, and curling, while dry root weight was measured at harvest. Compared to the control group (60%), cytidine (81%), exudate (80.5%), and the combination of Azospirillum with cytidine (80.5%) showed significantly higher shoot health on days 4-5. Furthermore, the combinations of Azospirillum with cytidine and Azospirillum with exudate maintained significantly higher shoot health than Azospirillum alone (63.3%) from days 4-7. At harvest, root dry weight was greater in the Azospirillum with cytidine and Azospirillum with exudate treatments compared to Azospirillum or exudate alone. These findings show that seedling exudates and cytidine function as prebiotic enhancers, strengthening plant-microbe interactions and improving shoot vigor and root biomass under drought. Future work will include microbial root analysis to assess how these treatments alter community structure, providing further insight into plant-microbe-prebiotic partnerships for legume resilience.