Elevated Ozone Concentration and Nitrogen Addition Increase Poplar Rust Severity by Shifting the Phyllosphere...

Area of Science:

• Environmental Science
• Plant Pathology
• Microbiology

Background:

• Tropospheric ozone (O3) and nitrogen (N) deposition are key pollutants affecting trees.
• Research often overlooks combined O3 and N effects on tree immunity and phyllosphere microbes.
• The interplay between host, pathogen, and environment is crucial for understanding tree health.

Purpose of the Study:

• To investigate the effects of elevated O3 and N addition on poplar leaf rust severity.
• To explore the relationship between O3/N-induced susceptibility and phyllosphere microbial community changes.
• To determine how environmental factors influence tree defense mechanisms via microbial interactions.

Main Methods:

• Utilized Free-Air-Controlled-Environment (FACE) plots to simulate elevated O3 and N deposition.
• Assessed poplar leaf rust severity in two susceptible hybrid poplar clones (107 and 546).
• Employed Miseq amplicon sequencing to analyze phyllosphere microbial community composition and diversity.

Main Results:

• Clone 107 showed increased rust severity under elevated O3 or N alone, but N addition mitigated O3's negative impact.
• Clone 546 exhibited no significant change in rust severity under elevated O3 or N.
• Elevated O3 and N addition reduced microbial community complexity, potentially increasing rust severity.
• Melampsora larici-populina infection altered microbial composition and increased sensitivity to elevated O3.

Conclusions:

• Poplar rust severity is influenced by the combined effects of elevated O3 and N deposition.
• Phyllosphere microbial community structure plays a critical role in mediating tree responses to environmental stress and pathogen infection.
• Maintaining microbial diversity may be essential for enhancing poplar plant immunity against environmental changes and disease pressure.