Abstract:
Objective Structure and diversity of rhizosphere bacterial communities at fields of mulberry trees resistant (QZ2K) or susceptible (QZ2G) to wilt disease were studied.
Method The V3-V4 regions of 16S rRNA in rhizosphere bacteria were amplified and sequenced using high-throughput sequencing technology on Illumina MiSeq to determine the bacterial community structure, diversity, and functions. Results from the two field samples were compared.
Result (1) At phylum and genus levels, the dominant rhizosphere bacteria were similar at QZ2K (Kangqing 283×Kangqing 10 mulberry field) and at QZ2G (Guisangyou 62 mulberry field). The phyla included Proteobacteria, Actinobacteria, Acidobacteria, Gemmatimonadetes, and Bacteroidetes, while the genera consisted of MND1, Gaiella, Nitrospira, Haliangium, and Streptomyces. (2) Although no significant difference in the alpha diversity of the bacteria communities at the two different fields, the NMDS ordination showed significant differences (stress 0.005<0.05). At QZ2K, the bacteria related to significant metabolic functions were Nitrospira, Acidobacteriia, Nitrospirales, Solibacteraies, Acidobacteriales, Nitrospiraceae, and the uncultured Acidobacteria, Solibacteraies Subgroup 3, and Solibacteraies Subgroup 2. At QZ2G, only Ilumatobacteraceae and TRA3-20-other were identified. (3) According to the Wilcoxon signed rank test, the 763 different rhizosphere bacteria orthologs identified were only 17.25% of all COG orthologs on both fields.
Conclusion There were no significant differences in the richness and diversity of rhizosphere bacteria community between the two fields. However, the bacteria associated with significant functions differed significantly between them, which could well be the species that made the difference in the occurrence of wilt disease on the mulberry plants. The information obtained in this study was of value for further studies on the microecological characteristics of mulberry rhizosphere as well as selection and application of functional bacteria for wilt control.