Biological nitrogen fixation and <i>nif</i>H gene expression in dry beans (<i>Phaseolus vulgaris</i> L.)
Bibliographic record
Abstract
Akter, Z., Pageni, B. B., Lupwayi, N. Z. and Balasubramanian, P. M. 2014. Biological nitrogen fixation and nif H gene expression in dry beans ( Phaseolus vulgaris L.). Can. J. Plant Sci. 94: 203–212. Dry bean (Phaseolus vulgaris L.) is one of the least efficient nitrogen (N 2 ) fixers among legumes (approximately 30 to 50 kg N ha −1 ). To identify efficient N 2 fixers, 22 dry bean genotypes were screened for symbiotic N 2 -fixation in potted low-N soil in the greenhouse under four treatments: (1) uninoculated, (2) inoculated with commercial Rhizobium leguminosarum bv. phaseoli inoculant Nitrastik-D ® , (3) inoculated with commercial Rhizobium inoculant Nodulator ® , and (4) fertilizer N added. Expression of nitrogenase reductase (nifH) gene in selected uninoculated genotypes (nodulated by indigenous rhizobia) was quantified by reverse transcription polymerase chain reaction (RT-PCR) to know if expression of this gene was an indicator of N 2 -fixation. Nitrogen fixation potential varied among the genotypes and between the rhizobia inoculants. Genotypes differed in shoot (5.17 to 8.39 g plant −1 ) and root (1.71 to 6.44 g plant −1 ) dry weights, nodule number (0 to 155 nodules plant −1 ) and mass (0.055 to 0.250 mg plant −1 ), and N 2 -fixed (0 to 129 mg N plant −1 ). Genotypes GH–196, FR 266 and AC Redbond fixed the most N 2 (60 to 112 mg N plant −1 ) with either rhizobial inoculant, and Viva fixed the highest amount (129 mg N plant −1 ) when inoculated with Nitrastik-D. In contrast, AC Black Diamond, Island, Winchester, AC Polaris, LEF 2RB and SEA 5 had low N 2 -fixing potential (3 to 23 mg N plant −1 ) in inoculated treatments. The qRT-PCR analysis indicated that nifH gene expression was 5 fold higher in GH-196 compared to the non-nodulating mutant R99, which further confirmed the high N 2 -fixation capacity of GH-196. After confirmation in the field, dry bean genotypes with improved N 2 -fixation potential identified in this study may be used as parents in breeding programs in the development of future cultivars. The nifH gene expression may be used as a rapid test to select dry beans with high N 2 -fixation potential.
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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 | 0.001 | 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 | 0.001 |
| 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".