Mapping of QTLs associated with adaptation to mega-environments using Canadian x Chinese populations in soybean
Bibliographic record
Abstract
Soybean ('Glycine max' [L.] Men) breeding programs frequently use elite lines as parents in crosses. The use of exotic germplasm as source of parents has been avoided due to a limited success of developing superior lines from the progeny. The reasons for this include the lack of adaptation of plant introductions (PI) and the difficulty in introgressing specific favourable alleles from the PI without accompanying negative alleles at other loci in the genome. The objectives of this thesis were: (a) to determine whether quantitative trait loci (QTL) appear in specific environments or universally; (b) to determine the existence of epistatic effects and evaluate their effect; (c) to determine which agronomic and morphological traits are correlated with yield; (d) to determine what additional traits were associated with yield QTL; (e) to determine if QTL associated with yield-component traits behave as mega-environment-universal QTL (QTLU) or megaenvironment-specific QTL (QTLSP); (f) to confirm yield and agronomic trait QTL in different genetic backgrounds. Two crosses between a Canadian elite line and a Chinese elite line were performed to develop two recombinant inbred line (RIL) populations, derived from the crosses, OAC Millennium * Heinong 3 8, and Pioneer 9071 * 8902. Both RIL populations were evaluated in multiple field locations in China and Canada from 2004 to 2006. A linkage map was developed based on OAC Millennium * Heinong 3 8 cross and 18 QTL for seed yield were identified. Of the 18, seven QTLU and 11 QTLSP were identified based on their behaviour across mega-environments. Multiple epistatic effects were identified across the map including QTL that are associated with yield and random QTL. Four traits (R1, R5, R8, and plant height), were correlated with seed yield. QTLu and QTLsp were identified for several agronomic traits. Yield QTL were not confirmed in the validation population derived from P9071 * 8902, which could imply that the seed yield QTL from the original population were not stable in this particular genetic background or alleles could be fixed in both parental lines. However, several agronomic trait QTLSP were found and one QTLSP was confirmed in the second population. An improved understanding of the type of QTL action as either universal or mega-environment specific and their interaction reported in this thesis may facilitate a strategic QTL-based introgression of genetic variation from exotic germplasm sources into breeding programs.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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 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".