Study of the physiological and biochemical characteristics of Cupriavidus metallidurans YX16 and growth-promoting on maize seedlings under salt stress.
TL;DR
Findings indicate that Cupriavidus metallidurans YX16 is a salt-tolerant plant growth-promoting rhizobacterium (PGPR) that effectively alleviates salt-induced damage and promotes maize growth, providing a basis for the development of microbial agents for the amelioration of saline-alkali soils.
Abstract
Background
Driven by the dual pressures of continuous global population growth and dwindling arable land, ensuring food security has become a paramount challenge for human society. However, soil salinization, a primary abiotic stress factor limiting agricultural production, is degrading vast tracts of arable land globally and causing drastic reductions in crop yields. Consequently, harnessing microorganisms to enhance crop adaptability to saline-alkaline environments has become a critical focus in the reclamation and utilization of these degraded soils.
Results
In this study, a salt-tolerant plant growth-promoting bacterium, Cupriavidus metallidurans strain YX16, was isolated from the red soil of Yunnan Province in China. It is characterized by salt tolerance, nitrogen fixation, inorganic phosphorus solubilization, and indole-3-acetic acid (IAA) production (83.75 ± 1.14 µg/mL), but lacks the ability to solubilize potassium and organic phosphorus, and it does not produce siderophores or 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Under salt stress, compared to the control group, the YX16 suspension treatment elevated the primary root length, plant height, root dry weight, shoot fresh weight, and shoot dry weight by 23.95%, 52.45%, 28.38%, 51.46%, and 107.69%, respectively. Furthermore, the total root length and root surface area increased by 44.08% and 32.48%, respectively. Inoculation with the YX16 suspension also promoted the accumulation of osmotic regulatory substances in maize, thereby activating the antioxidant system and reducing the malondialdehyde (MDA) content in roots and leaves by 27.50% and 49.57%, respectively. Under non-salt stress conditions, compared with the uninoculated control, the YX16 treatment decreased the root soluble sugar content by 20.64% and the leaf CAT activity by 13.08%, but elevated the root proline content by 29.16%, the root dry weight by 18.75%, and the leaf chlorophyll content by 12.74%; however, other antioxidant enzyme (SOD, POD) activities and root dehydrogenase activity (DHA) were not significantly affected.
Conclusions
These findings indicate that Cupriavidus metallidurans YX16 is a salt-tolerant plant growth-promoting rhizobacterium (PGPR) that effectively alleviates salt-induced damage and promotes maize growth, providing a basis for the development of microbial agents for the amelioration of saline-alkali soils.