ACC deaminase-producing rhizosphere bacteria modulate plant responses to flooding

Flooding events are predicted to increase over the coming decades, calling for a better understanding of plant responses to submergence. Specific root-associated microbes alter plant hormonal balance, affecting plant growth and stress tolerance. We hypothesized that the presence of such microbes may modulate plant responses to submergence.
We tested whether root-associated bacteria producing the enzyme ACC (1-aminocyclopropane-1-carboxylate) deaminase affect submergence responses in Rumex palustris, a flood tolerant riparian plant. Ethylene is a key plant hormone regulating flood–associated acclimations and ACC deaminase activity of bacteria may decrease ethylene levels in the plant. Rumex palustris plants were inoculated with Pseudomonas putida UW4 or an isogenic mutant lacking ACC deaminase, and subsequently exposed to complete submergence.
Submergence triggered ethylene-mediated responses, including an increase in leaf elongation and shoot fresh weight. Flood responses, including p...