Heat waves intensify the effects of drought on bacterial diversity but not community composition in Solanum lycopersicum soil

Abstract

Droughts and heat waves are expected to occur in combination more frequently under climate change; however, the interactive effect of these extreme events on soil microorganisms remains poorly understood. Here, we investigated the effects of drought, heat wave, and rehydration on bacterial diversity and community composition in Solanum lycopersicum grown soil. A growth chamber experiment with two factors (drought and heat wave) was conducted. Seedlings of Solanum lycopersicum were grown in well-watered or moderate drought stress at ambient temperature prior to a 7-day heat wave treatment. Rewatering from drought was conducted after the heat wave treatment. Soils were sampled at three time points, and bacterial 16S ribosomal RNA genes extracted from total soil DNA were amplified by PCR. Results showed that heat wave significantly affected bacterial diversity and community composition, while drought only significantly affected community composition. Their combination had significant interactive effect on diversity but not community composition. Moderate drought slightly increased bacterial diversity, but heat wave plus drought caused a decline in diversity. Heat wave stress suppressed the recovery of bacterial diversity from drought stress. Our results suggest that heat wave can aggravate the effect of drought on soil bacterial diversity, and the combination of heat wave and drought stress causes a lower recovery potential for bacterial diversity, indicating that extreme weather events would strongly affect belowground bacterial community composition in future climatic scenarios.