Root bacterial endophytes alter plant phenotype, but not physiology

Area of Science:

• Plant biology
• Microbiology
• Ecology

Background:

• Plant traits like root and leaf area affect environmental interactions.
• Plant microbiota can significantly influence plant morphology and physiology.
• Understanding plant-microbe interactions is crucial for plant science.

Purpose of the Study:

• To investigate the impact of three distinct bacterial strains from the Populus root microbiome on Populus trichocarpa plant phenotype.
• To assess how bacterial inoculation affects plant growth and physiological traits.

Main Methods:

• Inoculation of Populus trichocarpa with three bacterial strains differing in metabolic and hormonal capabilities.
• Measurement of plant growth traits (root:shoot ratio, biomass, root and leaf growth rates).
• Assessment of physiological traits (chlorophyll content, net photosynthesis, A_sat, A_max).

Main Results:

• Bacterial root endophyte infection increased root growth rate by up to 184% and leaf growth rate by up to 137%.
• No significant influence on total plant biomass or key photosynthetic traits (net photosynthesis, chlorophyll content).
• Evidence of plant morphological modification in response to bacterial presence.

Conclusions:

• Bacterial root endophytes can significantly alter plant morphology, specifically growth rates of roots and leaves.
• While not increasing overall biomass or carbon fixation, bacterial inoculation modifies carbon allocation within the host plant.
• These findings highlight the complex interplay between Populus plants and their root microbiomes.