Differential Abundance Analysis of "Core" Bacteriobiota During Key Growth Stages of Maize

Abstract

Numerous microbial taxa are used as biofertilizers because they have the potential to competitively colonize the rhizosphere or root interior of plants and promote nutrient uptake. The aim was to investigate the shifts of keystone bacterial species in maize roots and rhizosphere during seedling stage, flowering, and harvest, under different treatments of bacterial phytobiotic (PHY), poultry manure (PM) and their combination (PHY_PM). Soil bacterial communities remained largely unchanged regardless of the treatment applied or phenophase studied, with uncultured Gaiellales and Bacillus being the most abundant. In contrast, bacterial communities in roots differed in terms of distribution and relative abundance (RA) of different taxa between growth stages and treatments. The most abundant bacterial taxa in the roots during the initial seedling stage was Pseudomonas. In the flowering, Bacillus occurred with a two- to threefold higher RA in treatments with PHY or PM compared to the negative control, while Lechevalieria dominated during the harvest. Differential abundance analysis at the seedling stage showed a reduction of Pseudomonas in roots treated with PHY, while Pseudonocardia was significantly more abundant in roots treated with PM than in the other samples. Massilia, Streptomyces, Lechevalieria, Microbacteriaceae, Aeromicrobium, Sphingomonas and Roseiflexaceae were significantly higher in the PHY_PM treated root samples. Steroidobacter and Bdellovibrio were absent in PHY and PM treated root samples during flowering, while Bdellovibrio was significantly reduced in PHY_PM treatment compared to the negative control. RA of Bradyrhizobium and Polaromonas was reduced in PHY treated root samples, and Dongia was completely absent. Gaiellales was significantly more abundant, while Sphingomonas was less abundant in roots treated with PM and PHY_PM. Solirubrobacter and Bdellovibrio were absent from roots during harvest in all three treatment types. Pajaroellobacter was completely absent in PHY and PM treatments, while Steroidobacteraceae were present only in PHY and Cyclobacteriaceae in PM. Mucilaginibacter calamicampi showed significantly higher RA in PHY_PM treatment, while Sphingomonas was reduced. Considering the non-disruptive effect of PHY on the "core" bacteriobiota and the positive effects on the presence of beneficial bacterial genera, such products could be proposed as a promising alternative to chemicals and organic fertilizers in maize cultivation.