Warming Shapes and -Type Denitrifier Communities and Stimulates NO Emission in Acidic Paddy Soil.

Warming strongly stimulates soil nitrous oxide (NO) emission, contributing to the global warming trend. Submerged paddy soils exhibit huge NO emission potential; however, the NO emission pathway and underlying mechanisms for warming are not clearly understood. We conducted an incubation experiment using N to investigate the dynamics of NO emission at controlled temperatures (5, 15, 25, and 35°C) in 125% water-filled pore space. The community structures of nitrifiers and denitrifiers were determined via high-throughput sequencing of functional genes. Our results showed that elevated temperature sharply enhanced soil NO emission from submerged paddy soil. Denitrification was the main contributor, accounting for more than 90% of total NO emission at all treatment temperatures. NO flux was coordinatively regulated by , , and -containing denitrifiers but not ammonia-oxidizing archaea or ammonia-oxidizing bacteria. The -containing denitrifiers were more sensitive to temperature shifts, especially at a lower temperature range (5 to 25°C), and showed a stronger correlation with NO flux than that of -containing denitrifiers. In contrast, -containing denitrifiers exhibited substantial variation at higher temperatures (15 to 35°C), thereby playing an important role in NO consumption. Certain taxa of - and -containing denitrifiers regulated NO flux, including -containing denitrifiers affiliated with and as well as -containing denitrifiers affiliated with and . Together, these findings suggest that elevated temperature can significantly increase NO emission from denitrification in submerged paddy soils by shifting the overall community structures and enriching some indigenous taxa of - and -containing denitrifiers. The interdependence between global warming and greenhouse gas NO has always been the hot spot. However, information on factors contributing to NO and temperature-dependent community structure changes is scarce. This study demonstrated high-temperature-induced NO emission from submerged paddy soils, mainly via stimulating denitrification. Further, we speculate that key functional denitrifiers drive NO emission. This study showed that denitrifiers were more sensitive to temperature rise than nitrifiers, and the temperature sensitivity differed among denitrifier communities. NO-consuming denitrifiers (-containing denitrifiers) were more sensitive at a higher temperature range than NO-producing denitrifiers (-containing denitrifiers). This study's findings help predict NO fluxes under different degrees of warming and develop strategies to mitigate NO emissions from paddy fields based on microbial community regulation.