Rhizosphere microbiome dynamics and hormonal interactions regulating tiller development in sugarcane cultivars

Sugarcane tillering is a key determinant of crop productivity, yet the integrated roles of rhizosphere microbiome dynamics, nutrient status, and hormone signaling in regulating tiller development remain poorly understood. Here, we compared rhizosphere microbial communities, endogenous hormone profiles, and nutrient element concentrations in sugarcane cultivars with contrasting tillering capacities. High-tillering varieties exhibited significantly greater microbial diversity and more complex co-occurrence network structures in the rhizosphere, characterized by enrichment of Acidobacteriota, Chloroflexi, and Planctomycetes and functional pathways related to nitrogen fixation, phosphorus solubilization, and auxin biosynthesis. In contrast, low-tillering varieties harbored simplified, stress-adapted microbial consortia and prioritized pathways linked to oxidative stress response and heavy metal detoxification. Hormonal analysis revealed that high-tillering cultivars maintained higher levels of growth-promoting hormones-particularly auxin (IAA) and active cytokinins-in tiller buds while low-tillering cultivars accumulated elevated abscisic acid (ABA) and inactive cytokinin conjugates. Nutrient analysis indicated that high-tillering genotypes possessed higher nitrogen and phosphorus contents, supporting vigorous axillary bud activation and shoot proliferation, whereas low-tillering varieties accumulated more zinc and manganese, potentially reflecting stress adaptation. Network-level integration of microbial, hormonal, and nutrient profiles underscored genotype-specific feedback between rhizosphere microbiota and plant physiological states, highlighting modular associations that link microbial hubs with tissue-specific nutrient and hormone signatures. Our findings reveal a systems-level mechanism by which rhizosphere microbial community structure and function interact with plant-nutrient-hormonal status to regulate tillering in sugarcane. These insights provide a basis for microbiome-informed strategies to enhance sugarcane productivity through integrated nutrient-hormonal-microbe management.