Evaluation of antagonistic activities against Pythium myriotylum and plant growth promoting traits of Streptomyces isolated from Cocoyam (Xanthosoma sagittifolium (L.) Schott) rhizosphere
Bibliographic record
Abstract
The focus of this study was to isolate, evaluate and characterize cocoyam rhizospheric actinobacteria collected from Mount Cameroon for their potential antagonistic activities against Pythium myriotylum, the causative agent of cocoyam root rot disease, and/or their ability to promote plant growth. Actinobacteria were isolated from soil samples by using serial dilution method. Dual culture assay was used to screen the isolates against fungal phytopathogens including P. myriotylum. The selected isolates were characterized morphologically, physiologically, biochemically and genetically. Furthermore, these isolates were subjected to in vitro production of various plant growth promoting (PGP) traits. Among the 287 isolates distributed into 12 distinct groups, PFK4, PFBOT7 and PFEL2 had high antagonistic effects against P. myriotylum and they were regarded as promising candidates for further study of their biocontrol ability. The identification of actinobacterial isolates was done using universal PCR of partial 16S rRNA sequences combined with bioinformatics and phylogenetic procedures. The results revealed that all these isolates belong to the genus Streptomyces spp. The isolate PFK4 showed 99% similarity with Streptomyces albulus while PFBOT7 showed 99% similarity with Streptomyces albus and PFEL2 showed 98% similarity with Streptomyces gandoceansis based on their 16S rRNA gene sequences. In this study for the first time, we report S. gandocaensis strain for the biological control of Pythium myriotylum. The role of these isolates in Plant Growth Promotion (PGP) by in vitro production of PGP traits such as phosphate solubilisation, siderophore, indole-3-acetic acid (IAA), ACC deaminase and cell wall degrading enzymes production were also evaluated and showed as potential PGP agents. Concurrent production of PGP substances coupled with broad spectrum of antifungal and antibacterial activities of these three strains suggest their potential use as promising biocontrol and PGP tools for the development of an alternative control method for cocoyam cultivation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".