Adaptation to chronic drought modifies soil microbial community responses to phytohormones

Area of Science:

• Plant-soil interactions
• Microbial ecology
• Environmental stress physiology

Background:

• Drought stress impacts plants and soil microbes, triggering adaptive responses.
• Plant-soil signaling, particularly via phytohormones, plays a role in these responses.
• Limited understanding exists regarding microbial community responses to phytohormones under chronic drought.

Purpose of the Study:

• To investigate how chronic drought affects soil microbial community responses to phytohormone signaling.
• To test the hypothesis that long-term drought modifies microbial perception of plant stress signals.

Main Methods:

• Addition of three key phytohormones (abscisic acid, 1-aminocyclopropane-1-carboxylic acid, jasmonic acid) to soils.
• Utilizing soils from a long-term (25-year) field experiment with established climate treatments (drought vs. irrigation).
• Measurement of soil respiration and analysis of microbial functional groups.

Main Results:

• Phytohormone addition generally increased soil respiration, but this effect was more pronounced in irrigated soils compared to droughted soils.
• Increased soil respiration at low phytohormone concentrations was not attributable to microbial substrate utilization.
• Distinct phytohormone-induced shifts in microbial functional groups were observed between droughted and irrigated soils.

Conclusions:

• Soil microbial communities adapted to drought exhibit altered responses to phytohormone inputs.
• Drought-adapted soil microorganisms may interpret phytohormones as stress signals, potentially enabling anticipation of drought conditions.
• This suggests a sophisticated microbial sensing mechanism for plant-derived stress signals in drought-prone environments.