Modulation of the rhizosphere microbiome in RB sugarcane cultivars and suppressive effects through the induction of Bacillus and Priestia

Sugarcane (Saccharum spp.) stands out as one of the crops of greatest economic and strategic importance to agribusiness. Crop yield is sometimes limited by biotic factors and the incidence of plant pathogens. There is a growing need for sustainable strategies that integrate the production and use of beneficial microorganisms as alternatives. The bioinoculation with plant growth-promoting bacteria, especially the genera Bacillus and Priestia, is important for plant development, biocontrol and suppression of plant pathogens. The objective of this study was to evaluate the effect of bioinoculation with BPCV bacteria on the modulation of the rhizosphere microbiome, biocontrol of pathogens, and the initial performance of sugarcane genotypes (RB867515, RB92579, RB007818, and RB008791). The study was conducted under controlled conditions, in both substrate and soil, using two treatments (T1-BPCV and T2-no BPCV), and evaluated microbiological, phytosanitary, and agronomic parameters. In vitro performance tests identified significant reductions in the mycelium of Fusarium sp. phytonematodes by Bacillus amyloliquefaciens (95%), Bacillus subtilis (94%), and Bacillus velezensis (92%). Against Colletotrichum sp., reductions were observed due to Bacillus subtilis (98%) and Priestia aryabhattae (96%). Bioinoculation promoted superior plant growth in the RB genotypes; RB92579, grown on substrate (T1-BPCV), achieved 100% tillering, 360 tillers, and a plant height of 181 cm (60 DAP). The highest dry biomass yield (substrate) was observed in RB007818 (T1) with a total yield of 0.640 g, and RB867515 (T1) had a higher above-ground biomass yield (58.97%) than T2. Regarding chlorophyll content (TC) in the substrate, RB92579 (T1-BPCV) had an average TC of 46.51%, and in the soil, RB007818 (T1-BPCV) had an average TC of 48.10%. In phytosanitary biocontrol, it reduced the population density by an average of 62.4% and achieved 70% suppression of Pratylenchus zeae. The multifunctionality of BPCVs offers an alternative to green biotechnology and promotes sustainability in Saccharum spp.