A Bacillus velezensis strain isolated from oats with disease-preventing and growth-promoting properties.

Endophytes have been shown to promote plant growth and health. In the present study, a Bacillus velezensis CH1 (CH1) strain was isolated and identified from high-quality oats, which was capable of producing indole-3-acetic acid (IAA) and strong biofilms, and capabilities in the nitrogen-fixing and iron carriers. CH1 has a 3920 kb chromosome with 47.3% GC content and 3776 code genes. Compared genome analysis showed that the largest proportion of the COG database was metabolism-related (44.79%), and 1135 out of 1508 genes were associated with the function "biosynthesis, transport, and catabolism of secondary metabolites." Furthermore, thirteen gene clusters had been identified in CH1, which were responsible for the synthesis of fifteen secondary metabolites that exhibit antifungal and antibacterial properties. Additionally, the strain harbors genes involved in plant growth promotion, such as seven putative genes for IAA production, spermidine and polyamine synthase genes, along with multiple membrane-associated genes. The enrichment of these functions was strong evidence of the antimicrobial properties of strain CH1, which has the potential to be a biofertilizer for promoting oat growth and disease resistance.

Succession of tissue microbial community during oat developmental.

Investigating oat tissue microflora during its different developmental stages is necessary for understanding its growth and anti-disease mechanism. In this study, 16S rDNA and ITS (Internally Transcribed Spacer) high-throughput sequencing technology were used to explore the microflora diversity of oat tissue. Twenty-seven samples of leaves, stems, and roots from three developmental stages, namely the seedling stage (SS), jointing stage (JS), and maturity stage (MS), underwent sequencing analysis. The analysis showed that 6480 operational taxonomic units (OTUs) were identified in the examined samples, of which 1698 were fungal and 4782 were bacterial. Furthermore, 126 OTUs were shared by fungi, mainly Ascomycota, Basidiomycota, and Mucoromycota at the phylum level, and 39 OTUs were shared by bacteria, mainly Actinobacteriota and Proteobacteria at the phylum level. The microbial diversity of oat tissue in the three developmental stages showed differences, and the α-diversity of the bacteria and ß-diversity of the bacteria and fungi in the roots were higher than those of the stems and leaves. Among the bacteria species, Thiiopseudomonas, Rikenellaceae RC9 gut group, and Brevibacterium were predominant in the leaves, MND1 was predominant in the roots, and Lactobacillus was predominant in the stems. Moreover, Brevibacterium maintained a stable state at all growth stages. In the fungal species, Phomatospora was dominant in the leaves, Kondoa was dominant in the roots, and Pyrenophora was dominant in the stems. All species with a high abundance were related to the growth process of oats and antagonistic bacteria. Furthermore, connection modules were denser in bacterial than in fungal populations. The samples were treated with superoxide dismutase and peroxidase. There were 42 strains associated with SOD (Superoxide dismutase), 60 strains associated with POD (Peroxidase), and 38 strains in total, which much higher than fungi. The network analysis showed that bacteria might have more dense connection modules than fungi, The number of bacterial connections to enzymes were much higher than that of fungi. Furthermore, these results provide a basis for further mechanistic research.