Genetic characterization reveals no role for the reported ABA receptor, GCR2, in ABA control of seed germination and early seedling development in Arabidopsis
Bibliographic record
Abstract
Abscisic acid (ABA) is perceived by several different types of receptors in plant cells. At the cell surface, the ABA signal is proposed to be perceived by GCR2, which mediates ABA responses in seed germination, early seedling development and stomatal movement. GCR2 was also proposed to be a seven-transmembrane (7TM) G-protein-coupled receptor (GPCR). Here we characterize GCR2 and one of its two homologs, GCR2-LIKE 1 (GCL1), in ABA-mediated seed germination and early seedling development in Arabidopsis. We show that loss-of-function mutations in GCL1 did not confer ABA insensitivity. Similarly, we did not observe ABA insensitivity in three independent gcr2 alleles. Furthermore, we generated gcr2 gcl1 double mutants and found that the double mutants still had near wild-type responses to ABA. Consistent with this, we found that the transcription of ABA marker genes was induced by ABA to levels that were comparable in wild type and gcr2 and gcl1 single and double mutants. On the other hand, the loss-of-function alleles of the sole Arabidopsis heterotrimeric G protein alpha subunit, GPA1, were hypersensitive to ABA in the ABA-inhibition of seed germination and early seedling development, disfavoring a genetic coupling of GCR2 by GPA1. Using multiple robust transmembrane prediction systems, GCR2 was predicted not to be a 7TM protein, a structural hallmark of GPCRs. Taken together, our results do not support the notion that GCR2 is an ABA-signaling GPCR in seed germination and early seedling development.
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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 | 0.000 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".