Bacterial endophytes enhance competition by invasive plants

Area of Science:

• Plant-microbe interactions
• Soil biogeochemistry
• Invasive species ecology

Background:

• Invasive plants significantly alter soil microbial communities and ecosystem functions.
• Rhizome-associated bacterial endophytes in invasive Sorghum halepense contribute to these disruptions.
• Understanding these interactions is crucial for managing invasive species.

Purpose of the Study:

• To investigate the effects of nitrogen-fixing bacterial endophytes from S. halepense on plant growth.
• To determine how these bacteria alter soil nutrient cycles, facilitating the plant's persistence.
• To elucidate the mechanisms of bacterial recruitment and transmission in S. halepense.

Main Methods:

• Assessed soil nutrient fluxes over four years in S. halepense-invaded sites.
• In vitro assays of bacterial isolates for phosphate solubilization, iron chelation, and indole-3-acetic acid (IAA) production.
• Evaluated bacterial recruitment and vertical endophyte transmission; used antibiotics to assess microbial contributions to plant growth.

Main Results:

• Observed persistent alterations in eight key biogeochemical cycles (N, P, Fe) in invaded soils.
• Bacterial isolates exhibited phosphate solubilization, iron chelation, and IAA production in vitro.
• Antibiotic treatment significantly reduced S. halepense growth rate, biomass, and rhizome development, confirming microbial contribution.

Conclusions:

• Bacterial endophytes play a critical role in the growth and resource allocation of invasive S. halepense.
• The physiological traits of bacterial endophytes correlate with their impact on soil biogeochemical cycles.
• Targeting these microbial interactions could offer novel strategies for invasive plant management.