Elucidating the growth-promoting factors of Bacillus amyloliquefaciens on rapeseed through metabolomics
Bibliographic record
Abstract
BACKGROUND: Plant Growth-Promoting Rhizobacteria (PGPR), such as Bacillus amyloliquefaciens, play vital roles in enhancing plant growth and stress tolerance. This study aims to evaluate the effects of the B. amyloliquefaciens strain Bam22 on the growth and metabolic profile of rapeseed (Brassica napus) seedlings, specifically focusing on uncovering the underlying metabolic mechanisms. RESULTS: Inoculation with Bam22 significantly promoted rapeseed growth. Compared to the control, plant height increased by approximately 17.1% and root length by 14.4% at 35 days post-inoculation (dpi). While leaf number remained no significant changed, fresh weight showed significant increases of approximately 70.3% (shoot, 7 dpi), 39.4% (shoot, 35 dpi), 23.8% (root, 7 dpi), and 26.8% (root, 35 dpi), respectively. Wide-targeted metabolomic analysis using UPLC-MS/MS detected 1,785 metabolites. Statistical analysis revealed significant time-dependent metabolic shifts. After 7 days, 192 metabolites were significantly up-accumulated, with notable enrichment in flavonoids (particularly flavonols, e.g., sophoraflavonoloside, FC = 3.39) and phenolic acids. At 35 dpi, 135 metabolites were up-accumulated, with significant enrichment in lipids (predominantly lysophosphatidylcholines-LPCs and lysophosphatidylethanolamines-LPEs) and flavonoids. Crucially, Bam22 induced a profound and directed reprogramming of flavonoid metabolism. Key changes included enhanced flux towards naringenin chalcone synthesis and the accumulation of specific anthocyanin precursors (e.g., cyanidin 3-O-glucoside, delphinidin 3-O-glucoside) and flavonols (e.g., Kaempferol-O-sophoroside). CONCLUSIONS: This study provides the first report linking a B. amyloliquefaciens strain to systemic reprogramming of the flavonoid metabolome in rapeseed, revealing its role as a key mechanism underlying PGPR-induced growth enhancement. This flavonoid-centric metabolic shift, potentially enhancing stress tolerance (e.g., UV protection) and facilitating beneficial plant-microbe communication, provides crucial mechanistic insights into plant-microbe interactions and highlights the potential of targeting flavonoid metabolism for developing Bam22-based biofertilizers to optimize rapeseed productivity.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".