Sex-Dependent Rhizosphere Microbial Dynamics and Function in Idesia polycarpa Throughout Floral and Fruit Development

Recent research indicates that male Idesia polycarpa exhibit greater adaptability to stressful environments compared to their female counterparts, as evidenced by distinct morphological and physiological traits. However, the link between this adaptability and the rhizosphere processes remains elusive. Here, we investigate the differences in root bacterial community structures between male and female plants at different developmental stages, identifying bacterial strains associated with plant sex through functional predictions. This study aims to inform the optimal allocation of male and female plants during cultivation and provide a theoretical basis for sex identification and breeding. Samples from 7-year-old male and female plants were collected during the flowering (May) and fruit ripening (October) stages. Rhizosphere nutrient content and bacterial diversity were analyzed using Illumina high-throughput sequencing technology. The results demonstrated that total nitrogen (TN), total carbon (TC), and available potassium (AK) varied between sexes at different times. During the flowering period, no significant differences were observed in the Shannon, Simpson, and Chao1 indices between male and female plants. However, at fruit maturity, the Chao1 and Shannon indices were significantly higher in male plants than in female plants. The predominant phyla of rhizosphere bacteria were Pseudomonadota, Acidobacteriota, and Actinomycetes. Interestingly, from flowering to fruit ripening, the dominant phyla in both male and female plants shifted from Actinomycetes to Pseudomonadota. A significant correlation was observed between pH and AK with rhizosphere bacteria (P < 0.05), with metabolism being the main functional difference. This study provides preliminary insights into the functional predictions and analyses of bacteria associated with Idesia polycarpa. These findings lay the groundwork for further investigation into the sex-specific differences in microbial flora across different developmental stages, elucidating the mechanisms underlying flora changes and offering theoretical support for the high-quality management of Idesia polycarpa.