Plant sexual variation modulates rhizospheric nutrient processes through the soil microbiome response to drought and rewetting in Populus cathayana

Drought affects the physiological environment of the soil microbiome and plants. However, the ability of drought and rewetting to regulate sex-specific soil nutrient availability with respect to bacterial- and fungal-mediated rhizospheric processes has not been clarified. The impact of drought and rewetting on soil bacterial and fungal communities and rhizospheric processes were examined in dioecious Populus cathayana females and males. Drought and rewetting affected the composition and abundance of the bacterial and fungal communities but not their diversity in the rhizosphere of both sexes. Male had more drought-tolerant fungi and bacteria in the rhizosphere of males than females in response to drought. The changing bacterial and fungal community composition promoted soil ammonification in the rhizosphere of female plants, whereas nitrification by ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) was accelerated in the rhizosphere of male plants. Rewetting reduced the sexual differences in the ratio of nitrate (NO3-) to ammonium (NH4+) in the rhizosphere. In the rhizosphere of females, the changes in fungal community composition were linked more strongly to soil N and P reactions during recovery compared with that in the bacterial community composition. Conversely, the bacterial community rather than fungal components was the main contributor to soil N reactions in the rhizosphere of males. Plant sex influenced the response and recovery of fungal and bacterial communities to drought, and sexual dimorphism was detected in the regulation of rhizospheric nutrient reactions. Our results emphasize the ecological relevance of plant sex in determining the response of soil microbial communities to drought and rewetting effects and their ecological functions in P. cathayana.