Application of silicate changes the network complexity of plant growth-promoting rhizobacteria in the rhizosphere of sugarcane genotypes

Abstract

Silicon (Si) plays a pivotal role in shaping the core microbiome of the rhizosphere. However, there exists a gap in our understanding regarding the influence of Si on the recruitment of plant growth-promoting rhizobacteria (PGPR). This study assessed the PGPR community within the rhizosphere of three sugarcane genotypes (G1 - RB021754, G2 - RB036066, and G3 - RB92579) under two conditions: with (Si+) and without (Si-) Si application. Rhizosphere samples were collected 120 days after sugarcane emergence, and the study evaluated the richness, diversity, composition, co-occurrence network, and niche occupancy of the PGPR community through 16S rRNA gene sequencing. Interestingly, Si and sugarcane genotypes were found to exert no significant impact on the richness, diversity, or composition of the PGPR community in the rhizosphere. The most prevalent PGPR genera in the sugarcane rhizosphere were identified as Bacillus, Sphingomonas, Paenibacillus, Streptomyces, and Mycobacterium. Notwithstanding, Si application did exhibit an influence on network complexity. Specifically, it increased complexity in G2 and G3 while decreasing it in G1. Niche occupancy analysis revealed that approximately 50 % of PGPR were generalists, with around 30 % being specialists. This study distinctly revealed that Si, when associated with different sugarcane genotypes, significantly impacts network complexity and the prevalence of generalist PGPR species within the rhizosphere.