Metagenomics-based exploration of plant growth-promoting rhizobacteria in wheat rhizosphere

Abstract:

Long before modern molecular tools existed, soil microbiologists recognized that the zone around plant roots harbours a microbial community distinct from bulk soil. This research used 16S rRNA amplicon sequencing to characterize bacterial communities in the rhizosphere of bread wheat (cv. Scepter) at six phenological stages at Murray-Darling Institute of Agriculture, Wagga Wagga, NSW, during 2023. A total of 3.42 million quality-filtered reads were obtained from 42 samples using Illumina MiSeq. Bacterial diversity peaked at booting with 1,824 OTUs and Shannon index 7.54, compared to 1,094 OTUs in bulk soil. Pseudomonas was most abundant at 28.1% at booting, followed by Bacillus (21.2% at heading) and Azospirillum (16.7% at booting). PICRUSt2 functional prediction showed enrichment of nitrogen fixation, phosphate solubilization, and IAA biosynthesis genes. These findings map temporal recruitment of beneficial bacteria and provide candidate genera for biofertilizer development in southern Australian grain systems.