Ethylene Affects Soil Multifunctionality in Maize Rhizosphere by Driving Sensitive Microbial Communities

Ethylene modulates plant fitness, but its role in rhizosphere soil multifunctionality remains unclear. This study demonstrates that endogenous ethylene suppresses C- and N-cycling functions while promoting organic P mineralization in the maize rhizosphere, ultimately diminishing the overall soil multifunctionality and attenuating its phenologically driven peak at the tasseling stage. Ethylene reshaped microbial community assembly by enriching opportunistic taxa (e.g., Actinobacteria) while reducing the diversity and relative abundance of sensitive taxa. Community composition (e.g., Bacillus) and α diversity of ethylene-sensitive taxa were negatively correlated with soil multifunctionality. Inoculation with ACC deaminase-producing Bacillus pumilus and Streptomyces gardneri (opportunistic strains) significantly elevated C- and N-cycling enzyme activities and boosted maize growth. However, a direct causal link between ACC deaminase production and these effects requires further experimental validation. Collectively, these findings elucidate that ethylene drives rhizosphere biogeochemical trade-offs through the selective filtering of microbial functional guilds, providing a theoretical foundation for rhizosphere microbiome management in crop production.