Differences of soil microbial community structures in rhizosphere between gynoecious and monoecious cucumbers

Cucumber sex expression is a key agronomic trait determining yield, but whether its formations is related to rhizosphere soil microbes remains poorly understood. This study compared the soil microbial community structures in rhizosphere between gynoecious and monoecious cucumbers to identify potential associations. The results showed that bacterial genera including Sphingomonas, norank_f__JG30-KF-CM45, and norank_f__norank_o__Saccharimonadales were significantly enriched in the rhizosphere of the gynoecious cucumber. In contrast, norank_f__norank_o__norank_c__KD4-96 and norank_f__norank_o__Rokubacteriales were significantly enriched in rhizosphere of the monoecious cucumbers. For fungi, genera such as Aspergillus, Plectosphaerella, and Chaetomella were enriched in rhizosphere of the gynoecious cucumbers. Conversely, Trichoderma, Emericellopsis, Collariella, and Cordana were significantly enriched in rhizosphere of the monoecious cucumbers. Functional prediction revealed that multiple nitrogen-cycling processes of bacterial communities, including nitrification, aerobic nitrite oxidation, nitrite ammonification, nitrate ammonification, aerobic ammonia oxidation, and arsenate respiration were detected in rhizosphere of the gynoecious cucumbers. By contrast, hydrocarbon degradation functions, particularly those for aromatic and aliphatic non-methane hydrocarbons were significantly enriched in rhizosphere of the monoecious cucumbers. Moreover, the rhizosphere of gynoecious cucumber harbored a higher abundance of saprotrophic and symbiotrophic fungi but a lower abundance of pathotrophic fungi compared to the monoecious cucumbers. These findings demonstrate that the composition and potential functions of the rhizosphere microbiome differ between gynoecious and monoecious cucumber, indicating that soil microbes in rhizosphere may play a role in the sex expression of cucumber varieties.