Serratia plymuthica F-06 promotes the growth of maize seedlings under salt stress

Abstract:

[Background] Studies have shown that some microorganisms can promote the growth and improve the salt tolerance of crops. [Objective] To study the physiological and biochemical characteristics of a strain named F-06 isolated from a saline-alkali field in northern Ningxia, and evaluate the growth-promoting effect of the strain on maize seedlings under salt stress. [Methods] Strain F-06 was identified based on the morphological, physiological, and biochemical characteristics and the 16S rRNA gene sequence. Its growth-promoting effect on maize seedlings was evaluated by the sand culture under 100 mmol/L NaCl stress. [Results] Strain F-06 was a short rod-shaped Gram-negative bacterial strain capable of growing normally within the ranges of 2%–10% NaCl and pH 8.0–11.0. It can fix nitrogen, solubilize organophosphorus and potassium, and produce siderophore, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and indole-3-acetic acid (IAA) and was identified as Serratia plymuthica. Compared with the control group without NaCl, 100 mmol/L NaCl significantly inhibited the growth of maize seedlings. The plant height, stem diameter, fresh weight of stems and leaves, dry weight of stems and leaves, fresh root weight, and dry root weight of maize seedlings in the NaCl+F-06 group increased by 11.36%, 15.97%, 36.63%, 18.42%, 8.54%, and 10.0%, respectively, compared with those in the NaCl group (P<0.05). In addition, the leaves of maize seedlings in the NaCl+F-06 group showcased increased content of proline, decreased content of chlorophyll and malondialdehyde (P<0.05), superoxide dismutase (SOD) activity decrease of 5.3%, peroxidase (POD) activity decrease of 61.9%, and catalase (CAT) activity increase of 40.33% compared with the NaCl group (P<0.05). [Conclusion] Strain F-06 promoted the growth of maize seedlings exposed to 100 mmol/L NaCl.