| Evidence type | Claim (reaction/substrate/localization/pathway) | Supporting source (paper title) | Publication date/year | URL/DOI | Notes/limitations |
|---|---|---|---|---|---|
| Direct evidence status for **NaBGLU18_1 / A0A314KWB2** | No direct biochemical or genetic characterization of **Nicotiana attenuata BGLU18_1** was identified in the retrieved literature; therefore specific substrate, reaction, pathway role, and localization remain unverified experimentally for this exact protein. (pqac-00000000, pqac-00000004, pqac-00000006) | Multiple retrieved sources surveyed; no paper directly characterizing A0A314KWB2/BGLU18_1 found | 2016-2024 | UniProt accession supplied by user: https://www.uniprot.org/uniprotkb/A0A314KWB2 | Critical limitation: annotation must rely on UniProt family/domain assignment and indirect GH1 knowledge unless future organism-specific evidence appears. |
| Indirect GH1 family/domain inference | A0A314KWB2 belongs to **glycoside hydrolase family 1 (GH1) beta-glucosidases**, so the most defensible core inference is that it is a retaining beta-glycosidase acting on glucosidic substrates, releasing beta-D-glucose plus an aglycone/ligand. (pqac-00000012, pqac-00000013) | *Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum*; *Genome-wide identification and expression analysis of the glycosyl hydrolase family 1 genes in Medicago sativa revealed their potential roles in response to multiple abiotic stresses* | 2024; 2024 | https://doi.org/10.1186/s12870-024-05919-3 ; https://doi.org/10.1186/s12864-023-09918-w | Indirect only; family-level prediction does not establish the natural substrate of NaBGLU18_1. |
| Indirect GH1 catalytic mechanism | Plant GH1 BGLUs typically have a **classical (beta/alpha)8 barrel** and **two catalytic carboxylates** operating by a **retaining double-displacement mechanism**. (pqac-00000012) | *Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum* | 2024 | https://doi.org/10.1186/s12870-024-05919-3 | Mechanistic inference is strong for GH1 enzymes but was not experimentally shown for A0A314KWB2. |
| Indirect substrate-spectrum inference | Plant GH1 BGLUs can hydrolyze glucosides involved in **cyanohydrin, alkaloid, phenylpropanoid, defense-compound, and phytohormone** metabolism; many also function in **cell wall remodeling**, scent release, and microbe/insect interactions. (pqac-00000012, pqac-00000013) | *Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum*; *Genome-wide identification and expression analysis of the glycosyl hydrolase family 1 genes in Medicago sativa revealed their potential roles in response to multiple abiotic stresses* | 2024; 2024 | https://doi.org/10.1186/s12870-024-05919-3 ; https://doi.org/10.1186/s12864-023-09918-w | Broad family properties only; they do not prove whether NaBGLU18_1 prefers hormone conjugates, defense glycosides, or other glucosides. |
| Indirect hormone-related functional analogy | Some plant GH1 members, notably **AtBGLU18** and **AtBGLU10**, hydrolyze **ABA-glucose ester (ABA-GE)** to release active **abscisic acid (ABA)**, linking GH1 enzymes to stress signaling. (pqac-00000012) | *Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum* | 2024 | https://doi.org/10.1186/s12870-024-05919-3 | Important analogy because the target symbol contains “BGLU18”, but this is **not evidence that Nicotiana attenuata BGLU18_1 is an ABA-GE hydrolase**. Gene symbols are potentially misleading across species. |
| Indirect localization analogy | Reported localizations for characterized plant GH1 BGLUs include **endoplasmic reticulum** for **AtBGLU18**, **vesicles** for **AtBGLU10**, and **chloroplast** for **Os3BGLU6**. (pqac-00000012) | *Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum* | 2024 | https://doi.org/10.1186/s12870-024-05919-3 | Localization of NaBGLU18_1 remains unknown; these examples only show that GH1 BGLUs occupy diverse intracellular compartments. |
| Indirect stress-pathway inference | GH1 BGLUs are frequently implicated in **biotic/abiotic stress responses** and can contribute by activating stored defensive chemicals or phytohormone conjugates. (pqac-00000012, pqac-00000013) | *Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum*; *Genome-wide identification and expression analysis of the glycosyl hydrolase family 1 genes in Medicago sativa revealed their potential roles in response to multiple abiotic stresses* | 2024; 2024 | https://doi.org/10.1186/s12870-024-05919-3 ; https://doi.org/10.1186/s12864-023-09918-w | This supports a stress-related annotation at family level, but not a specific pathway assignment for A0A314KWB2. |
| Context from **Nicotiana attenuata** defense chemistry (not direct NaBGLU18_1 evidence) | In **N. attenuata**, **17-hydroxygeranyllinalool diterpene glycosides (HGL-DTGs)** are major defense metabolites, but their defensive activation is described as involving **post-ingestive hydroxylation** rather than a demonstrated plant GH1 beta-glucosidase cleavage step. (pqac-00000006, pqac-00000008, pqac-00000009) | *Harmonizing biosynthesis with post-ingestive modifications to understand the ecological functions of plant natural products* | May 2022 | https://doi.org/10.1039/d2np00019a | Highly relevant to N. attenuata specialized metabolism; however, this paper explicitly shifts emphasis away from assuming a plant beta-glucosidase trigger for HGL-DTG activation. |
| Context from **N. attenuata** HGL-DTG pathway | Prior to herbivory, geranyllinalool is hydroxylated by **NaCYP736As**, glycosylated by **UGT74P**, and later malonylated; disruption of these steps causes accumulation of autotoxic intermediates. (pqac-00000008) | *Harmonizing biosynthesis with post-ingestive modifications to understand the ecological functions of plant natural products* | May 2022 | https://doi.org/10.1039/d2np00019a | Relevant pathway background for N. attenuata; no direct role for NaBGLU18_1 shown. |
| Context from insect-plant interaction | In *Manduca sexta*, **only the glucose at C-17** of HGL-DTGs is removed by an **insect midgut beta-glucosidase**, representing a **detoxification** step for the herbivore rather than a demonstrated plant enzymatic step. (pqac-00000009) | *Harmonizing biosynthesis with post-ingestive modifications to understand the ecological functions of plant natural products* | May 2022 | https://doi.org/10.1039/d2np00019a | Important limitation: these beta-glucosidase data concern the herbivore, not NaBGLU18_1. |
| Quantitative, non-target comparison from *Manduca* PMRi | Plant-mediated RNAi lines targeting larval genes reduced *M. quinquemaculata* **CYP6B46** and **BG1** transcripts by about **90%** and **80%**, respectively, showing strong silencing of insect detoxification genes on transgenic **N. attenuata** plants. (pqac-00000010) | *Plant-mediated RNAi silences midgut-expressed genes in congeneric lepidopteran insects in nature* | Nov 2017 | https://doi.org/10.1186/s12870-017-1149-5 | Included because requested and relevant to HGL-DTG context, but this is **not** evidence about plant NaBGLU18_1 function. |
| Quantitative, non-target comparison from *Manduca* PMRi and dissertation evidence | PMRi studies/dissertation report **ca. 90% CYP6B46** and **ca. 75% BG1** transcript reduction in larval midguts, with **98%** and **96%** sequence similarity between PMRi constructs and homologs. (pqac-00000007, pqac-00000011) | *Probing the herbivores responses to plant defenses using plant-mediated RNAi*; *Plant-mediated RNAi silences midgut-expressed genes in congeneric lepidopteran insects in nature* | 2016; 2017 | DOI unavailable in retrieved text for dissertation; https://doi.org/10.1186/s12870-017-1149-5 | Values vary slightly by source/reporting context (75% vs 80% BG1 reduction). These are insect-gene silencing data, not NaBGLU18_1 measurements. |
| Quantitative metabolite effects in insect BG1 silencing | Midgut extracts from **beta-glucosidase1-silenced** larvae produced **55% less RGHGL** (partially deglycosylated lyciumoside IV product); silenced larvae excreted **40% more lyciumoside IV** and **70% less RGHGL** than controls. (pqac-00000003, pqac-00000005) | *Probing the herbivores responses to plant defenses using plant-mediated RNAi* | 2016 | DOI unavailable in retrieved text | Useful quantitative benchmark for HGL-DTG detoxification, but all measurements concern **insect** BG1 activity, not the plant protein A0A314KWB2. |
| Quantitative HGL-DTG induction in plant upon herbivory | Total **HGL-DTG concentrations** in **N. attenuata** leaves increased significantly after herbivory (**F1,4 = 36.88, P <= 0.0037; n = 3**), with contributions from lyciumoside IV, Nic1, and Nic2. (pqac-00000000, pqac-00000007) | *Probing the herbivores responses to plant defenses using plant-mediated RNAi* | 2016 | DOI unavailable in retrieved text | Demonstrates the defensive metabolite context in the correct organism, but does not identify NaBGLU18_1 as the responsible enzyme for any step. |
| Functional interpretation relevant to annotation | The safest current annotation for **BGLU18_1 / A0A314KWB2** is therefore: **putative GH1 beta-glucosidase** with probable retaining glycosidase activity on an as-yet-unknown plant glucoside substrate; possible involvement in stress or specialized metabolism is plausible but unproven. (pqac-00000012, pqac-00000013, pqac-00000008) | Family/domain and plant-defense context synthesized from retrieved sources | 2022-2024 | https://doi.org/10.1186/s12870-024-05919-3 ; https://doi.org/10.1186/s12864-023-09918-w ; https://doi.org/10.1039/d2np00019a | This is an inference-based functional annotation, explicitly distinct from direct experimental characterization. |


*Table: This table distinguishes direct evidence for Nicotiana attenuata BGLU18_1 from indirect GH1 family knowledge and related N. attenuata defense literature. It is useful for functional annotation because it makes clear which claims are experimentally supported for the exact target and which remain inference-based.*