Molecular, cytogenetic, anatomical, and morphological variations associated with polyploids of prairie cordgrass
Bibliographic record
Abstract
Climate change or global warming, gradually increase in average global temperature, is now well documented and accepted by scientists as fact. The main cause of climate change is increasing carbon dioxide level (CO2) in the atmosphere. Bio-renewable energy sources can play a role in providing energy services to meet basic human needs in sustainable manner, in particular, in migrating climate change. However, the current bioenergy sources face both social and environmental challenges, mainly because they use food crops which lead to land-use competition between food and liquid biofuels. In order to minimize competition with food crops, the next generation bioenergy sources should be grown on marginal lands, where food crops cannot be grown. Prairie cordgrass (Spartina pectinata Link) has been recommended as a dedicate energy crop grown on marginal land. This species is tall (1-3 m), rhizomatous, C4 perennial grass, native to North America, and commonly found in lower, poorly drained soils along roadside, ditches, stress, marshes, wet meadows, and potholes. Prairie cordgrass is well known as polyploid species, including tetra- (2n=40), hexa- (2n= 60), and octoploids (2n=80), and has high abiotic stress tolerances such as salinity, cold, and waterlogging. Prairie cordgrass is successfully adapted in wide geographic distribution throughout Canada to 60° N latitude and in the United States throughout the Northeast, Great Lakes, and Midwest states, as well as most other states. According to previous studies, U.S. geographic distribution of this species is closely related to ploidy levels. Only tetraploid populations are found in the New England region, while most octoploids are distributed in the West North Central regions. Populations of tetra- and octoploids were found in close proximity in the West North Central and the West South Central regions.Unlike tetra- and octoploids, neo-hexaploids have only been reported in a single location co-existing with tetraploids. Since the polyploid evolutionary process in prairie cordgrass is dynamic, it is critical to understand how the polyploidization events influence on genetic diversity, chromosome structural changes, and morphological variations within the species. Through chloroplast DNA (cpDNA) phylogenetic analyses, three distinct genetic haplotypes were identified, which are relatively associated with geographic distribution and ploidy level. Genetic diversity in polyploids has resulted in variation in the number of silver stained NORs (AgNORs) on chromosomes at metaphase. The distribution patterns of AgNORs in metaphase cells of tetra- and octoploids appears to reflect changes in ploidy. Two populations of tetra- and octoploids have the number of AgNORs expected from their mitotic metaphase chromosome number. Four AgNORs were found in tetraploids, while octoploids have eight AgNORs. However, two hexaploids have differing numbers of AgNORs (3 and 6), indicating that chromosome structure may not be stabilized in early generations of neo-polyploidy. This recent polyploidization event also appears to have modified morphological characteristics such as stem height, thickness, and mass, which are strongly associated with lodging resistance. Hexaploid populations have higher lodging resistance than their putative tetraploid populations due to specific morphological characteristics such as shorter height or thicker and heavy stem. Overall, the past and new polyploidization events may develop novel molecular, cytogenetical, anatomical, and morphological characteristics in prairie cordgrass. Therefore, the results of this study plays an important role in understanding the creation of genetic diversity which is a critical factor for developing prairie cordgrass as a dedicated energy crop grown in stressful environmental conditions.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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".