| Claim/annotation category | Specific finding | Experimental system/method | Conditions (e.g., control/NaCl/ABA) | Interpretation for functional annotation | Source (include DOI URL and year) |
|---|---|---|---|---|---|
| identity | CASPL1D1 corresponds to Arabidopsis thaliana locus **At4g15610** and is discussed as one of four **CASPL** proteins previously identified as interactants of aquaporin **PIP2;1**. | Gene/protein identification in Arabidopsis root studies; prior interactor-based selection summarized in paper | Arabidopsis roots | Confirms the target is the Arabidopsis **CASP-like protein 1D1** rather than a different similarly named gene from another species. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000004) |
| domain/family | CASPL1D1 belongs to the **CASP-LIKE (CASPL)** family; Barbosa et al. describe **CASPs/CASPLs** as a plant-specific branch of the **MARVEL** family with multiple transmembrane domains involved in membrane-domain organization. | Family-level comparative and functional analysis of CASP/CASPL proteins | General Casparian strip context | Supports annotation of AtCASPL1D1 as a small multi-pass membrane protein likely acting as a membrane-domain/scaffold component rather than an enzyme or transporter with known catalytic substrate. | Barbosa et al. 2023, Nat Commun. DOI: https://doi.org/10.1038/s41467-023-37265-7 (2023) (pqac-00000011, pqac-00000012) |
| expression | **CASPL1D1 shows GUS activity in root tips and younger tissues** and is reported as **mostly expressed in the cortex close to the root tip and continuously along the root**; this pattern was confirmed by **CASPL1D1::GFP**. | Promoter-GUS and GFP fusion expression analysis | Arabidopsis roots under standard conditions | Indicates a tissue-biased role in root cortex/plasma membrane biology rather than exclusive endodermal Casparian strip assembly. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000000) |
| expression | In contrast to CASPL1B1, CASPL1B2 and CASPL1D2, **CASPL1D1 is not described as exclusively expressed in suberized endodermal cells** in the provided evidence. | Comparative expression interpretation from reporter analyses | Arabidopsis roots | Suggests AtCASPL1D1 may function outside the canonical endodermal suberized domain emphasized for other CASPL paralogs. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000000, pqac-00000004) |
| subcellular localization | **CASPL1D1 localizes to the plasma membrane in cortical cells** and, unlike CASPL1B2, is **excluded from the Casparian strip domain (CSD)**. | CASPL1D1::GFP localization microscopy | Arabidopsis root cortical cells | Strongly supports annotation as a **plasma-membrane structural/regulatory protein** rather than a lumenal or wall-localized factor; exclusion from the CSD argues against a direct core-CASP role in CSD formation. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000000) |
| interactions | CASPL1D1 is reported among four CASPL proteins that **copurify with GFP-PIP2;1**, and the authors note potential **coexpression/colocalization with PIP2;1** at the plasma membrane of cortical cells. | Copurification/proteomics plus expression-localization comparison | Arabidopsis roots | Supports a probable association with aquaporin regulatory complexes, but does **not** by itself establish direct binding or channel regulation by CASPL1D1. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000000, pqac-00000001, pqac-00000003) |
| interactions | Direct physical interaction/function was demonstrated in the study for **CASPL1B1** and for interaction testing of **CASPL1D2**, but **equivalent direct FRET/functional proof is not reported for CASPL1D1** in the provided snippets. | FRET-FLIM / heterologous functional assays summarized in excerpt | Arabidopsis / assay-specific | Functional annotation for AtCASPL1D1 should remain conservative: **association with PIP2;1 is supported, direct mechanistic regulation is not yet established** from the provided evidence. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000002, pqac-00000003) |
| mutant/phenotype | **Single caspl1d1** mutants and **caspl1d1 caspl1d2** double mutants showed **no detectable alteration of endodermal suberization under standard growth conditions** in one summary, but other analyses found a **slight enlargement of the continuous suberization zone** in the double mutant. | T-DNA/transposon loss-of-function analysis with suberization phenotyping | Mainly control conditions | Indicates any role of AtCASPL1D1 in barrier formation is **weak/modulatory**, likely partially redundant with CASPL1D2. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000000, pqac-00000001) |
| mutant/phenotype | Under **NaCl stress**, the **caspl1d1 caspl1d2** double mutant showed a somewhat stronger continuous suberization phenotype; **no phenotype after ABA** treatment was reported for this trait. | Root suberization assays in mutant lines | Control, NaCl, ABA | Supports a context-dependent role in modulating suberization, especially under salt stress, but not a major ABA-dependent pathway role based on current evidence. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000001, pqac-00000004) |
| mutant/phenotype | **No significant differences** were detected for **root hydraulic conductivity (Lpr)**, **osmotic permeability (Lpr-o)**, **solute exudation fluxes (Js)**, or **root/shoot dry weight** in caspl1d1-related mutant backgrounds under tested conditions. | Root hydraulics, solute flux, and biomass phenotyping | Control, NaCl, ABA as tested | Suggests AtCASPL1D1 is **not a major determinant of whole-root water transport** or gross growth under the tested experimental settings. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000000, pqac-00000001, pqac-00000003, pqac-00000004) |
| quantitative stats | **CASPL1D1 transcript abundance decreased by 73% in caspl1d1.1 and 76% in caspl1d1 caspl1d2** relative to control. | RT-qPCR in mutant lines | Mutant versus control | Confirms substantial knockdown/disruption in the analyzed mutant material, supporting interpretation of phenotype tests as informative for gene function. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000001) |
| quantitative stats | In the **caspl1d1 caspl1d2** double mutant, the **continuous endodermal suberization zone** was reported as **42% vs 36% in control** under standard conditions and **56% vs 50% in control** under **NaCl** treatment. | Quantification of suberization pattern in mutant and control roots | Control and NaCl | Quantitatively supports a **slight negative role** for CASPL1D1/CASPL1D2 in limiting continuous suberization. | Champeyroux et al. 2019, Plant Cell Environ. DOI: https://doi.org/10.1111/pce.13537 (2019) (pqac-00000001) |
| domain/family | In the broader family context, **CASP proteins** are small **four-transmembrane-span**, endodermis-specific MARVEL-family proteins that form stable **Casparian strip membrane domains (CSDs)**, mediate membrane-wall adhesion, and help create membrane exclusion zones. | CASP quintuple-mutant analysis, imaging, proximity labeling, mechanistic modeling | Arabidopsis endodermis | Although this evidence concerns **CASP1-5 rather than CASPL1D1 directly**, it provides the best current mechanistic framework for inferring that CASPL proteins are membrane-domain organizers/scaffolds. | Barbosa et al. 2023, Nat Commun. DOI: https://doi.org/10.1038/s41467-023-37265-7 (2023) (pqac-00000008, pqac-00000011) |
| domain/family | Barbosa et al. tested extra **CASPL** knockouts in a **caspQ 6x-caspl** background and found **no enhancement** of the caspQ phenotype, arguing that tested CASPLs do **not compensate** for loss of core CASPs in Casparian strip assembly. | Higher-order mutant analysis | Casparian strip formation context | Suggests AtCASPL1D1 is unlikely to be a simple functional substitute for core CSD-forming CASPs and may have a distinct, more peripheral role. | Barbosa et al. 2023, Nat Commun. DOI: https://doi.org/10.1038/s41467-023-37265-7 (2023) (pqac-00000009) |
| quantitative stats | Family-level quantitative/mechanistic result: **at least three CASPs**—most effectively **CASP1, CASP3 and CASP5**—were needed to complement the **caspQ** mutant; single or double CASPs were insufficient. | Complementation analysis in caspQ | Casparian strip assembly assays | Reinforces that CSD function depends on cooperative assembly of membrane scaffolds; by analogy, CASPL1D1 may also act in complexes rather than alone, though this remains inferential for AtCASPL1D1. | Barbosa et al. 2023, Nat Commun. DOI: https://doi.org/10.1038/s41467-023-37265-7 (2023) (pqac-00000007) |


*Table: This table compiles gene-specific evidence for Arabidopsis AtCASPL1D1 (At4g15610; Q9FE29) from Champeyroux et al. 2019 and relevant family/mechanistic context from Barbosa et al. 2023. It separates direct findings on expression, localization, interactions, and mutant phenotypes from broader CASP/CASPL inferences useful for functional annotation.*