CNGCs break through—A rice cyclic nucleotide-gated channel paves the way for pollen tube growth
Bibliographic record
Abstract
Rice cyclic nucleotide-gated channel 13 is a novel player in pollen tube-pistil signalingLower plants generate mobile sperm cells that must reach their female counterparts by swimming.This requirement for water is a disadvantage for these plants as compared with angiosperms, for which the dry pollen attaches to a stigma and becomes hydrated, enabling the emerging pollen tube to grow in the protected environment of the pistil.After adhesion, hydration, and germination of the pollen at the stigmatic papilla cells, the pollen tube enters the stigma and grows in the intercellular space between papilla cells towards the style and transmission tract (TT).The TT contains a nutrient-rich extracellular matrix (ECM) and guides the pollen tube to the ovary.After penetrating the septum, the pollen tube grows through the funiculus and then enters the ovule though the micropyle to deliver the two nonflagellate sperm cells to the two female gametes, leading to double fertilization, a prerequisite to seed formation [1].The 2017 study by Xu et al. [2] reveals, for the first time, the importance of a Ca 2+ signal generated by rice cyclic nucleotide-gated channel 13 (OsCNGC13) in the pistil to induce programmed cell death (PCD), which facilitates proper pollen tube growth.Furthermore, they showed this step significantly affects the yield of rice grains.The events during pollen grain-stigma interaction and pollen tube reception are relatively well studied [1, 3], while much less is known about the growth of the pollen tube through the style and TT tissue-particularly the signaling between the pollen tube and the pistil tissue(s).Intracellular signaling in the pollen tube during pollen tube growth has been studied extensively [4].The role of Ca2+ is well established: in the pollen tube, a Ca2+ gradient is essential for pollen tube guidance [5].External Ca2+ from the pistil must be taken up by the pollen tube and is required for its growth.Several potential Ca2+ channels that are expressed in the pollen tube have been identified in Arabidopsis.These include two glutamate receptor-like (GLR) channels (GLR1.2 and GLR3.7) [6] and six cyclic nucleotide-gated channels (CNGCs; CNGC7, 8, 9, 10, 16, and 18), of which CNGC18 has been shown to be a Ca2+-conducting channel that is essential for tip growth in pollen tubes [7] and pollen tube guidance (Fig 1) [5].Pollen tubes can grow in vitro; however, for the pollen tube to make its way through the style to the ovary, some communication with the sporophyte is necessary.But so far, few signaling components have been identified that drive the interaction between the TT and the pollen tube.On the pollen tube side, two membrane-localized leucine rich repeat (LRR) receptor kinases, LePRK1 and 2, have been identified that may interact with different ligands in different pistil tissues [8].Other examples include the pollen tube-localized GLRs, GLR1.2 and
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.004 | 0.003 |
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".