| Topic | Evidence/Findings (concise) | Species/Context | Key citation (with DOI URL and pub month/year if available) |
|---|---|---|---|
| Target identity/disambiguation | The target matches the potato **CCoAOMT** family concept: a SAM-dependent class I-like O-methyltransferase with the canonical **Methyltransf_3/PF01596** domain and conserved motifs used to identify potato StCCoAOMTs; however, retrieved literature did **not** directly map **UniProt Q8H9B6** to a specific **Soltu.DM** locus, so accession-level mapping remains indirect. | *Solanum tuberosum*; family-level verification for Q8H9B6 | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000003, pqac-00000006) |
| Canonical reaction / EC | CCoAOMT is the **SAM-dependent caffeoyl-CoA O-methyltransferase (EC 2.1.1.104)** that methylates **caffeoyl-CoA to feruloyl-CoA** in the monolignol pathway; this is the core annotation consistent with UniProt Q8H9B6. | General plant CCoAOMT; potato family paper reiterates canonical reaction | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466; Martz et al., *Plant Mol Biol* (Feb 1998), https://doi.org/10.1023/A:1005969825070 (pqac-00000003, pqac-00000014) |
| Substrate specificity (best biochemical evidence) | Recombinant tobacco CCoAOMT was **highly active with caffeoyl-CoA and 5-hydroxyferuloyl-CoA esters**, but showed **no activity toward the corresponding free acids** (caffeic acid, 5-hydroxyferulic acid), supporting CoA-ester specificity. | Biochemical evidence from tobacco, widely used to infer true CCoAOMT specificity | Martz et al., *Plant Mol Biol* (Feb 1998), https://doi.org/10.1023/A:1005969825070 (pqac-00000014, pqac-00000015) |
| Functional diversification within family | Modern family analyses distinguish **true CCoAOMTs** (lignin-associated) from **CCoAOMT-like/PFOMT** proteins that can methylate flavonoids/anthocyanins; thus, not every StCCoAOMT family member should be assumed to share strict lignin-pathway specificity. | Plant-wide interpretation applied to potato StCCoAOMT family | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000008, pqac-00000012) |
| Pathway placement | True CCoAOMT functions in the **phenylpropanoid/monolignol/lignin biosynthesis pathway**, helping generate G-lignin precursors and feeding substrate toward S-lignin formation downstream. | General plant pathway context; relevant to potato lignification/wound-healing interpretation | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466; Liu et al., *Front Plant Sci* (Oct 2023), https://doi.org/10.3389/fpls.2023.1216702 (pqac-00000008, pqac-00000011) |
| Potato family size and domain architecture | A 2024 potato genome-wide study identified **12 StCCoAOMT genes**; all have a single **AdoMet_Mtases** superfamily domain, and **motif 1** is present in all 12 members. | *S. tuberosum* cultivar DM | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000024, pqac-00000025, pqac-00000016) |
| Potato family loci from Peng 2024 | Reported loci include **StCCoAOMT1 = Soltu.DM.01G047320; StCCoAOMT2 = Soltu.DM.02G028520; StCCoAOMT3 = Soltu.DM.02G028530; StCCoAOMT4 = Soltu.DM.02G028540; StCCoAOMT5 = Soltu.DM.02G028550; StCCoAOMT6 = Soltu.DM.03G003400; StCCoAOMT7 = Soltu.DM.04G025040; StCCoAOMT8 = Soltu.DM.04G025050; StCCoAOMT9 = Soltu.DM.08G001680; StCCoAOMT10 = Soltu.DM.09G025040; StCCoAOMT11 = Soltu.DM.10G014940; StCCoAOMT12 = Soltu.DM.12G013090**. | *S. tuberosum* cultivar DM | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000018) |
| Potato phylogenetic inference for lignin-linked members | **StCCoAOMT1–5, 11, 12** cluster with **AtCCoAOMT1** in subgroup Ia, which the authors interpret as the **lignin-biosynthesis-associated clade**; this makes these the strongest potato candidates for canonical EC 2.1.1.104-like function. | *S. tuberosum* family phylogeny | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000017) |
| Potato members implicated in flavonoid/anthocyanin metabolism | **StCCoAOMT6, 7, 8, 10** fall in a different subgroup and are discussed as candidates for **flavonoid/anthocyanin-related methylation** rather than purely lignin-associated roles. | *S. tuberosum* family phylogeny/expression | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000012, pqac-00000024) |
| Predicted subcellular localization in potato family | WoLF PSORT predictions placed about **66.67% (8/12)** of StCCoAOMTs in the **cytoplasm**; **StCCoAOMT4/5** in the **cytoskeleton** and **StCCoAOMT8/9** in the **chloroplast**. Specific predictions include **StCCoAOMT1,2,3,6,7,10,11,12 = cytoplasm**. | *S. tuberosum* family-wide predictions | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000017, pqac-00000018) |
| Experimental localization in potato | **StCCoAOMT10-GFP** localized mainly to the **cytoplasm and nucleus** in *Nicotiana benthamiana* transient assays; this is the strongest experimental localization evidence currently available from potato CCoAOMTs. | Potato gene assayed in tobacco leaves | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000011, pqac-00000013, pqac-00000026) |
| Tissue expression in potato | Expression is diverse by tissue: **StCCoAOMT1** broadly expressed; **StCCoAOMT7** strongly expressed in **stolons**; **StCCoAOMT9** relatively high in **leaves/petals/stamens**; **StCCoAOMT10** high in **sepals, shoots, and tubers**. | *S. tuberosum* transcript profiling | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000016, pqac-00000025) |
| Potato anthocyanin-related candidate | **StCCoAOMT10** was highlighted as significantly expressed in **purple potatoes** with high anthocyanin content, making it a leading candidate for potato anthocyanin methylation; the authors note the exact potato catalytic roles still require direct functional confirmation. | Purple-fleshed potato tubers | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000024, pqac-00000025) |
| Expert/author interpretation for potato | The 2024 potato study explicitly states that the **key CCoAOMT gene(s) and precise function in anthocyanin methylation in potato have not yet been systematically elucidated**, so family-member functions should be treated as candidates/inferences unless directly tested. | Caveat for functional annotation in potato | Peng et al., *Genes* (Nov 2024), https://doi.org/10.3390/genes15111466 (pqac-00000025) |
| 2023 engineering result: tobacco knockout | CRISPR knockout of **CCoAOMT6/6L** in tobacco increased the **S/G lignin monomer ratio** and enhanced resistance to **bacterial wilt** and **brown spot**, illustrating that CCoAOMT perturbation can reprogram lignin composition and disease outcomes. | *Nicotiana tabacum* | Liu et al., *Front Plant Sci* (Oct 2023), https://doi.org/10.3389/fpls.2023.1216702 (pqac-00000004) |
| 2023 engineering result: C-lignin | In *Medicago truncatula* hairy roots, **C-lignin accumulation of up to 15% of total lignin** required strong down-regulation of **CCoAOMT** together with **COMT** loss of function. | *Medicago truncatula* lignin engineering | Ha et al., *Biotechnol Biofuels Bioprod* (Jun 2023), https://doi.org/10.1186/s13068-023-02339-7 (pqac-00000003) |
| 2024 engineering result: cotton | Silencing **GhCCoAOMT7** caused a **56% reduction in stem lignin** and visibly reduced phloroglucinol-stained xylem area, supporting a strong positive role in lignification. | *Gossypium hirsutum* | Ma et al., *Plants* (Oct 2024), https://doi.org/10.3390/plants13212969 (pqac-00000023) |
| 2024 broader methyl-donor engineering result | In sorghum, reducing **S-adenosylmethionine** availability (thereby impacting SAM-dependent O-methyltransferases including CCoAOMT/COMT) reduced lignin by **18%** in the best line and increased glucose yield after pretreatment/saccharification by **~20%**; this demonstrates the practical leverage of the methylation step for biomass engineering, though it is not CCoAOMT-specific. | *Sorghum bicolor* | Tian et al., *Biotechnol Biofuels Bioprod* (Oct 2024), https://doi.org/10.1186/s13068-024-02572-8 (pqac-00000005) |
| Overall annotation confidence for Q8H9B6 | High confidence for **family-level function** (potato CCoAOMT, SAM-dependent O-methyltransferase in phenylpropanoid metabolism), but **moderate confidence** for assigning a **specific StCCoAOMT locus/member** to **Q8H9B6** from the retrieved literature because no direct accession crosswalk was recovered. | UniProt-guided annotation of potato target | Supported jointly by potato family study and classical biochemistry: Peng et al. (Nov 2024) https://doi.org/10.3390/genes15111466; Martz et al. (Feb 1998) https://doi.org/10.1023/A:1005969825070 (pqac-00000003, pqac-00000014, pqac-00000017) |


*Table: This table summarizes the best-supported functional annotation points for potato CCOAOMT/Q8H9B6 and the broader StCCoAOMT family, including reaction chemistry, pathway placement, localization, potato loci, and recent quantitative engineering results from 2023-2024. It is useful as a compact evidence map separating direct biochemical evidence from potato-specific inference.*