Microbial Community Dynamics in the Rhizosphere of Sunflower and Comparative Oilseed Crops: Functional Roles and Strategies for Sustainable Agriculture

The rhizosphere represents a highly dynamic interface where plant roots interact with the surrounding soil matrix, fostering a diverse and functionally complex microbial community. These microbiota play essential roles in plant growth promotion, nutrient cycling, and resilience to biotic and abiotic stresses. In recent years, plant-associated microbial communities have garnered increasing attention for their potential to enhance agroecosystem sustainability. This review examines microbial community shifts in the rhizosphere and bulk soil of sunflower (Helianthus annuus), a key oilseed crop known for its adaptability to marginal soils and environmental stressors. The differences in microbial composition and functional potential between rhizosphere and bulk soil are analyzed, with emphasis on the roles of plant genotype, root exudation, and environmental variables such as salinity and climatic conditions. Particular focus is placed on beneficial bacterial genera including Pseudomonas, Azotobacter, and Bacillus, which contribute to nutrient acquisition and stress mitigation. Additionally, fungal taxa such as Fusarium, Aspergillus, and Alternaria are discussed in the context of decomposition, symbiosis, and plant–microbe interactions. Comparative insights from other oilseed crops—such as soybean, rapeseed, and peanut—are presented to contextualize microbiome patterns unique to sunflower. The functional attributes of rhizosphere microbes, including phytohormone production, pathogen suppression, and nutrient solubilization, are explored in detail. Furthermore, this review highlights microbiome engineering approaches, such as the application of biofertilizers and plant growth-promoting rhizobacteria (PGPR), aimed at improving crop productivity and resilience. The integration of high-throughput sequencing technologies and advanced bioinformatics has deepened our understanding of these complex microbial networks. Finally, the review identifies existing knowledge gaps and outlines future research directions to optimize rhizosphere microbiomes for enhanced agro-ecological performance in sunflower and related oilseed crops.