Characterization of Genetic Sources Associated with Restorability and Seed Dimension in Arkansas Restorer Rice Lines
Bibliographic record
Abstract
Hybrid rice (Oryza sativa L.) breeding offers a significant opportunity to enhance rice production, and the cultivation of a male sterile line is the most important factor in the success of cross-breeding. One of the key elements of hybrid rice production is to develop a restorer line that is assigned as the male parent. The restorer lines provide viable pollen for fertilization of the male sterile plant due to the presence of a restorer gene (Rf) in their genomes. Any superior restorer line applied to hybrid rice production must contain genes/quantitative trait loci (QTL) associated with the desirable agronomic traits in its genome. The objectives in this study were to 1) identify the genetic source of restorability in two Arkansas-developed restorer lines, 367R and 396R, and 2) identify QTLs associated with seed dimensions in two restorer lines. The study was performed at the University of Arkansas System Division of Agriculture, Rice Research and Extension Center, Stuttgart, Arkansas. Three populations resulting from crosses between 367R and Arkansas advanced lines RU1501139, and 396R crossed with Tropical Japonica cultivar “Newbonnet (PI474580) or Arkansas advanced line RU1501047 were developed. Five F3 plants from each F2:3 line were selected for testcross with an Arkansas developed cytoplasmic male sterile (CMS) line 873A. Five testcross F1 plants resulting from each selected pollen donor plant were grown in the greenhouse. Pollen fertility was tested via a pollen stain procedure (Virmani et al, 1997). The results showed that 367R contains one restorer gene and 396R possesses two restorer genes within their genomes. The genotypic analysis showed that there are two major QTLs, in chromosome (“chr” hereafter) 10, which is co-localized with two previously reported QTLs where Rf4 and Rf5 genes were mapped. For the second part of this study, the parental lines were evaluated for grain length, width, thickness, 100-seed weight, and heading date. The population 367R × RU1501139 (“Population-A”, hereafter) was selected for evaluation of grain length, thickness, and length/width ratio. A total of 300 F3 seeds from F2 plants grown in greenhouse conditions were harvested, cleaned and evaluated using the WinSEEDLE TM image analyzer (Regent Instruments Inc., Canada). A total of 17 QTLs for grain dimensions were identified. Two QTLs in chr. 3 and one each QTL in chr. 7 and 11 were associated with grain length, while two QTLs located in chrs. 3 and 7 were associated with grain length/width ratio. Three QTLs located in chrs. 5, 6, and 8 were associated with grain thickness, while nine grain weight QTLs were identified that included four QTLs in chr. 12, two QTLs in chrs. 1 and 10, and one QTL in chr. 3. These results can be used for developing superior restorer lines and applied to hybrid rice production via marker-assisted selection.
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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 | 0.000 |
| 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".