CYP79B3 (At2g22330) is an endoplasmic reticulum-anchored cytochrome P450 monooxygenase (tryptophan N-monooxygenase, EC 1.14.14.156) that converts L-tryptophan to indole-3-acetaldoxime (IAOx) using O2 and electrons supplied by NADPH-cytochrome P450 reductase. It shares about 85% amino-acid identity with its paralog CYP79B2, with which it acts redundantly. IAOx is a metabolic branch point: it is the precursor of indole glucosinolates (via CYP83B1), of the phytoalexin camalexin (via CYP71A12/A13 and CYP71B15/PAD3), and of a minor tryptophan-dependent route to indole-3-acetic acid through indole-3-acetonitrile. The cyp79b2 cyp79b3 double mutant lacks camalexin and indole glucosinolates and is partially auxin deficient. Unlike CYP79B2, CYP79B3 is not transcriptionally induced when camalexin synthesis is elicited by silver nitrate, but it responds to jasmonate, wounding and some herbivores, and is expressed in roots around lateral root primordia. Through its products it is required for resistance to fungal, oomycete and bacterial pathogens, for flg22-induced callose deposition, and for rhizobacterium-induced systemic resistance.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0002229 defense response to oomycetes | IGI PMID:20230487 Disease resistance of Arabidopsis to Phytophthora brassicae ... | KEEP AS NON CORE | Summary: The cyp79B2 cyp79B3 double mutant, which lacks IAOx and hence all IAOx-derived metabolites (indole glucosinolates and camalexin), is highly susceptible to the oomycete Phytophthora brassicae, whereas single pathway-branch mutants have only minor effects. Reason: Sound genetic evidence (IGI with CYP79B2) that CYP79B2/B3-derived indolic metabolites are needed for resistance to P. brassicae. CYP79B3 acts upstream by supplying the precursor IAOx; the antimicrobial work is done by downstream products (indole glucosinolate hydrolysis products and camalexin). Retained as a non-core, upstream physiological consequence of its catalytic role, as for CYP79B2. Supporting Evidence: PMID:20230487 In contrast, the double mutant cyp79B2 cyp79B3, which has a blockage in the production of indole-3-aldoxime (IAOx), the common precursor of tryptophan-derived metabolites including camalexin and iGS, is highly susceptible to P. brassicae. |
| GO:0004497 monooxygenase activity | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Generic monooxygenase activity from InterPro mapping of the cytochrome P450 domain. Reason: Correct but uninformative parent of the experimentally established tryptophan N-monooxygenase activity (GO:0090489), which captures the core activity. Retained as a true but non-core general term, as for CYP79B2. Supporting Evidence: PMID:10681464 We have identified two Arabidopsis cytochrome P450s (CYP79B2 and CYP79B3) that can convert Trp to indole-3-acetaldoxime (IAOx), a precursor to IAA and indole glucosinolates. |
| GO:0005506 iron ion binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Iron ion binding inferred from P450 domain signatures; the heme iron is coordinated by the conserved Cys479 thiolate (by similarity). Reason: CYP79B3 is a heme-thiolate P450; the iron is bound as part of the heme prosthetic group. The term is correct as a cofactor description but is not the core function. Supporting Evidence: file:ARATH/CYP79B3/CYP79B3-uniprot.txt Name=heme; Xref=ChEBI:CHEBI:30413; |
| GO:0005783 endoplasmic reticulum | IBA GO_REF:0000033 | ACCEPT | Summary: ER localization propagated across the CYP79/CYP71 clan P450 node; consistent with the N-terminal signal-anchor (TM 22-42) of CYP79B3 and with ER localization of its paralog CYP79B2. Reason: Plant A-type P450s are ER-anchored and CYP79B3 is inside the clade; the PAINT node placement is sound. There is no direct CYP79B3 localization study beyond an old N-terminal GUS fusion report, so the IBA is the best available location statement. The paralog CYP79B2 colocalizes with ER-resident CYP71A13. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001210282 · PTN001210282 SUPPORTS TRANSFER ER anchoring is conserved across this plant P450 node and CYP79B3 is inside the clade. Supporting Evidence: file:ARATH/CYP79B3/CYP79B3-deep-research-falcon.md directed a GUS reporter to plastids, but targeting programs disagreed, and plant P450s are commonly associated with the cytosolic face of the endoplasmic-reticulum membrane file:ARATH/CYP79B3/CYP79B3-uniprot.txt SUBCELLULAR LOCATION: Membrane {ECO:0000305}; Single-pass membrane |
| GO:0006569 L-tryptophan catabolic process | IDA PMID:10681464 Arabidopsis cytochrome P450s that catalyze the first step of... | ACCEPT | Summary: Recombinant CYP79B3 converts L-tryptophan to indole-3-acetaldoxime, a reaction that consumes tryptophan. Reason: Conversion of Trp to IAOx is a catalytic step that removes tryptophan into secondary and hormone metabolism, so CYP79B3 directly executes a step of tryptophan catabolism as broadly defined. The more informative processes are indole glucosinolate and camalexin biosynthesis, but this term is not wrong. Same treatment as CYP79B2. Supporting Evidence: PMID:10681464 We have identified two Arabidopsis cytochrome P450s (CYP79B2 and CYP79B3) that can convert Trp to indole-3-acetaldoxime (IAOx), a precursor to IAA and indole glucosinolates. |
| GO:0006952 defense response | IMP PMID:20023151 Tryptophan-derived metabolites are required for antifungal d... | KEEP AS NON CORE | Summary: Epistasis analysis with cyp79B2 cyp79B3 shows that indolic metabolites are required for mlo2-conditioned antifungal defense against powdery mildew and Botrytis. Reason: Genetic necessity of CYP79B2/B3-derived metabolites for antifungal defense; CYP79B3 acts upstream by producing IAOx. Retained as non-core; the core contribution is the biosynthetic step. No more specific defense response to fungus term is proposed, because the antifungal work is done by the downstream products, not by CYP79B3. Supporting Evidence: PMID:20023151 Results of genetic epistasis analysis suggest a decisive role for indolic metabolites in mlo2-conditioned antifungal defense against both biotrophic powdery mildews and a camalexin-sensitive strain of the necrotrophic fungus Botrytis cinerea. |
| GO:0009507 chloroplast | ISM GO_REF:0000122 | MARK AS OVER ANNOTATED | Summary: Chloroplast localization predicted by AtSubP sequence analysis. Reason: CYP79B3 has an N-terminal signal anchor typical of ER-resident plant P450s, and its paralog CYP79B2 colocalizes with ER-resident CYP71A13. An early report that an N-terminal CYP79B3-GUS fusion reached plastids exists, but targeting predictions disagree and a truncated fusion does not establish the location of the active full-length enzyme. Treated as an over-annotation from a sequence prediction rather than removed outright, given that unresolved fusion report. (The ISM chloroplast row on CYP79B2 was removed; CYP79B2 has direct ER colocalization data that CYP79B3 lacks.) Supporting Evidence: file:ARATH/CYP79B3/CYP79B3-deep-research-falcon.md directed a GUS reporter to plastids, but targeting programs disagreed, and plant P450s are commonly associated with the cytosolic face of the endoplasmic-reticulum membrane |
| GO:0009611 response to wounding | IEP PMID:17675405 A downstream mediator in the growth repression limb of the j... | KEEP AS NON CORE | Summary: CYP79B3 was among transcripts that are wound-inducible in a jasmonate-dependent manner in a microarray screen (gene list; CYP79B3 not discussed in the main text). Reason: Expression-based evidence; jasmonate inducibility of CYP79B3 is independently reported (methyl jasmonate induces CYP79B3 about 3.5-fold). The wound response is a regulatory context in which indole glucosinolate synthesis is raised, not a function of the enzyme itself. Non-core. Supporting Evidence: PMID:17675405 Combining the two lists produced a subset of 814 transcripts that were wound-inducible in wild-type plants but not wound-inducible in aos plants (i.e., these genes were wound-inducible in a jasmonate-dependent manner). file:ARATH/CYP79B3/CYP79B3-deep-research-falcon.md methyl jasmonate induced CYP79B3 transcript abundance |
| GO:0009617 response to bacterium | IMP PMID:23073694 Metabolic and transcriptomic changes induced in Arabidopsis ... | KEEP AS NON CORE | Summary: cyp79B2 cyp79B3 mutants fail to mount Pseudomonas fluorescens SS101-induced resistance against Pst. Reason: Genetic requirement for IAOx-derived metabolites in a rhizobacterium-induced response; CYP79B3 acts upstream as a biosynthetic enzyme. Non-core, as for CYP79B2. Supporting Evidence: PMID:23073694 Subsequent bioassays with seven Arabidopsis mutants ( myb51 , cyp79B2cyp79B3 , cyp81F2 , pen2 , cyp71A12 , cyp71A13 , and myb28myb29 ) disrupted in the biosynthesis pathways for these plant secondary metabolites showed that camalexin and glucosinolates are indeed required for the induction of Pst resistance by Pf .SS101 . |
| GO:0009625 response to insect | IEP PMID:23144921 Water stress and aphid feeding differentially influence meta... | KEEP AS NON CORE | Summary: Feeding by the aphid Brevicoryne brassicae increased CYP79B3 transcripts together with indole glucosinolate and camalexin accumulation. Reason: Expression-based response; indole glucosinolates produced downstream of CYP79B3 are established anti-herbivore metabolites, so the response is biologically plausible but non-core. Supporting Evidence: PMID:23144921 B. brassicae induced expression of CYP79B2 and CYP79B3 under drought and water-logged conditions, along with increased levels of 4-methoxyindol-3ylmetyl glucosinolate |
| GO:0009682 induced systemic resistance | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Induced systemic resistance propagated at a narrow CYP79B node (PTN008612649) containing CYP79B2 and CYP79B3. Reason: The node is the CYP79B subfamily and its experimental grounding is the CYP79B2/CYP79B3 mutant data (PMID:23073694); the target appearing among the sources is expected. The term reflects an upstream requirement for IAOx-derived defense metabolites rather than the enzymatic function, so it is kept as non-core, as for CYP79B2. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN008612649 · PTN008612649 SUPPORTS TRANSFER Narrow CYP79B node grounded by the cyp79B2 cyp79B3 double-mutant ISR data; CYP79B3 is one of the two genes assayed. The transfer is sound; the term is non-core for an upstream biosynthetic enzyme. Supporting Evidence: PMID:23073694 Subsequent bioassays with seven Arabidopsis mutants ( myb51 , cyp79B2cyp79B3 , cyp81F2 , pen2 , cyp71A12 , cyp71A13 , and myb28myb29 ) disrupted in the biosynthesis pathways for these plant secondary metabolites showed that camalexin and glucosinolates are indeed required for the induction of Pst resistance by Pf .SS101 . |
| GO:0009682 induced systemic resistance | IMP PMID:23073694 Metabolic and transcriptomic changes induced in Arabidopsis ... | KEEP AS NON CORE | Summary: Rhizobacterium (P. fluorescens SS101)-induced systemic resistance to Pst requires CYP79B2/B3-dependent camalexin and glucosinolates. Reason: Experimental support for necessity of CYP79B2/B3 products in ISR; the enzyme acts upstream by producing IAOx. Non-core. Supporting Evidence: PMID:23073694 Subsequent bioassays with seven Arabidopsis mutants ( myb51 , cyp79B2cyp79B3 , cyp81F2 , pen2 , cyp71A12 , cyp71A13 , and myb28myb29 ) disrupted in the biosynthesis pathways for these plant secondary metabolites showed that camalexin and glucosinolates are indeed required for the induction of Pst resistance by Pf .SS101 . |
| GO:0009684 indoleacetic acid biosynthetic process | IMP PMID:15772288 Sites and regulation of auxin biosynthesis in Arabidopsis ro... | KEEP AS NON CORE | Summary: IAA synthesis rate is reduced in roots of the cyp79B2 cyp79B3 double mutant; CYP79B3 is expressed around lateral root primordia, a site of high IAA synthesis. Reason: CYP79B3 makes IAOx, which can be converted to IAA via IAN, so it does catalyse an early step of one (minor, Brassicales-specific) Trp-dependent IAA route. Its contribution is conditional and quantitatively small relative to the TAA1/YUCCA pathway, so the term is retained as non-core, as for CYP79B2. Supporting Evidence: PMID:15772288 Root-localized IAA synthesis was diminished in a cyp79B2 cyp79B3 double knockout, suggesting an important role for Trp-dependent IAA synthesis pathways in the root. PMID:12464638 Conversely, cyp79B2 cyp79B3 double mutants have reduced levels of IAA and show growth defects consistent with partial auxin deficiency. |
| GO:0010112 regulation of systemic acquired resistance | IEP PMID:20081042 Arabidopsis auxin mutants are compromised in systemic acquir... | MARK AS OVER ANNOTATED | Summary: Truman et al. 2010 linked indole-derived compounds (not auxin itself) to the establishment of systemic acquired resistance, with transcriptional data on indolic pathway genes in systemically responding leaves. Reason: The annotation rests on expression (IEP). A change in CYP79B3 transcript during SAR does not show that a biosynthetic P450 regulates SAR; at most it supplies a precursor of indolic metabolites implicated in systemic immunity. Only the abstract is cached, so the specific data were not seen, but the evidence type cannot support a regulatory role for the enzyme. Supporting Evidence: PMID:20081042 our data provide compelling evidence for a role of indole-derived compounds, but not auxin itself, in the establishment and maintenance of systemic immunity |
| GO:0010120 camalexin biosynthetic process | TAS PMID:16167893 Secondary metabolites influence Arabidopsis/Botrytis interac... | ACCEPT | Summary: Traceable author statement on camalexin production by the CYP79B-dependent pathway in Arabidopsis/Botrytis interactions. Reason: CYP79B3 catalyses, redundantly with CYP79B2, the first step of camalexin biosynthesis (Trp to IAOx); the double mutant is devoid of camalexin and labelled IAOx is incorporated into camalexin. This is direct catalytic participation. CYP79B2 is the main pathogen-induced contributor, but CYP79B3 catalyses the same step. Supporting Evidence: PMID:16167893 Botrytis cinerea isolates showed differing sensitivity to purified camalexin, and camalexin-sensitive isolates produced larger lesions on camalexin-deficient Arabidopsis genotypes than on the wild type. PMID:15148388 We show that camalexin, the indole phytoalexin of Arabidopsis thaliana, is synthesized from tryptophan via indole-3-acetaldoxime (IAOx) in a reaction catalyzed by CYP79B2 and CYP79B3. |
| GO:0016020 membrane | IBA GO_REF:0000033 | MODIFY | Summary: Membrane localization propagated at the P450 node. Reason: CYP79B3 is a single-pass, signal-anchored membrane protein, so the term is correct, but the membrane for this clade is the ER; endoplasmic reticulum membrane is the precise term, consistent with the ER IBA from the same node and with the CYP79B2 review. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001210282 · PTN001210282 SUPPORTS TRANSFER Membrane anchoring is conserved across this P450 node and CYP79B3 is inside the clade; the MODIFY only sharpens the term to ER membrane, it does not dispute the transfer. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: file:ARATH/CYP79B3/CYP79B3-deep-research-falcon.md directed a GUS reporter to plastids, but targeting programs disagreed, and plant P450s are commonly associated with the cytosolic face of the endoplasmic-reticulum membrane file:ARATH/CYP79B3/CYP79B3-uniprot.txt SUBCELLULAR LOCATION: Membrane {ECO:0000305}; Single-pass membrane |
| GO:0016020 membrane | IEA GO_REF:0000044 | MODIFY | Summary: Membrane from UniProt subcellular location (single-pass membrane protein). Reason: Correct but non-specific; ER-anchored plant P450s of this clade, including the paralog CYP79B2, reside in the ER membrane, so endoplasmic reticulum membrane is the appropriate term. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: file:ARATH/CYP79B3/CYP79B3-uniprot.txt SUBCELLULAR LOCATION: Membrane {ECO:0000305}; Single-pass membrane file:ARATH/CYP79B3/CYP79B3-deep-research-falcon.md directed a GUS reporter to plastids, but targeting programs disagreed, and plant P450s are commonly associated with the cytosolic face of the endoplasmic-reticulum membrane |
| GO:0016705 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: General paired-donor oxygenase term from P450 domain mapping. Reason: True ancestor of tryptophan N-monooxygenase activity (GO:0090489) but uninformative; retained as non-core. Supporting Evidence: PMID:10681464 We have identified two Arabidopsis cytochrome P450s (CYP79B2 and CYP79B3) that can convert Trp to indole-3-acetaldoxime (IAOx), a precursor to IAA and indole glucosinolates. |
| GO:0016709 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, NAD(P)H as one donor, and incorporation of one atom of oxygen | IBA GO_REF:0000033 | MODIFY | Summary: Paired-donor monooxygenase with NAD(P)H as one donor, propagated at the P450 node PTN001210282. Reason: The general P450 monooxygenase function at this node is sound, but microsomal P450s such as CYP79B3 receive electrons from NADPH via NADPH-cytochrome P450 reductase (a flavoprotein); the Rhea reaction (RHEA:33279) uses reduced [NADPH--hemoprotein reductase]. In GO, tryptophan N-monooxygenase activity is_a GO:0016712 (reduced flavin or flavoprotein as one donor), not GO:0016709. Replace with GO:0016712, as done for CYP79B2. Propagation Review Root cause: TERM SCOPING PROBLEM Sources checked: PANTHER:PTN001210282 · PTN001210282 SUPPORTS TRANSFER The P450 monooxygenase function at this node is sound and CYP79B3 is inside the clade; only the electron-donor branch of the asserted term (NAD(P)H rather than flavoprotein reductase) is mis-scoped for microsomal P450s. Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen Supporting Evidence: file:ARATH/CYP79B3/CYP79B3-uniprot.txt Reaction=L-tryptophan + 2 reduced [NADPH--hemoprotein reductase] + 2 O2 |
| GO:0019761 glucosinolate biosynthetic process | TAS PMID:16167893 Secondary metabolites influence Arabidopsis/Botrytis interac... | MODIFY | Summary: Traceable author statement that CYP79B3 functions in glucosinolate biosynthesis, in a study using secondary-metabolite biosynthetic mutants to probe Botrytis sensitivity. Reason: CYP79B3 catalyses, redundantly with CYP79B2, the first committed step of indole (tryptophan-derived) glucosinolate biosynthesis; it has no role in aliphatic or benzyl glucosinolate synthesis, which use CYP79F/CYP79A2. The specific term is indole glucosinolate biosynthetic process (is_a glucosinolate biosynthetic process), the same process term used for CYP79B2. Proposed replacements: indole glucosinolate biosynthetic process Supporting Evidence: PMID:15148388 These results demonstrate that only CYP79B2 and CYP79B3 contribute significantly to the IAOx pool from which camalexin and indole glucosinolates are synthesized. PMID:16167893 Additional analysis with Arabidopsis secondary metabolite biosynthetic mutants suggests that Botrytis also has variable sensitivity to phenylpropanoids and glucosinolates. |
| GO:0020037 heme binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Heme binding from P450 domain signatures. Reason: CYP79B3 is a heme-thiolate P450 (Cys479 axial ligand by similarity). The cofactor-binding term is correct but not the core function. Supporting Evidence: file:ARATH/CYP79B3/CYP79B3-uniprot.txt Name=heme; Xref=ChEBI:CHEBI:30413; |
| GO:0042742 defense response to bacterium | IMP PMID:19095898 Glucosinolate metabolites required for an Arabidopsis innate... | KEEP AS NON CORE | Summary: cyp79B2 cyp79B3 plants, lacking indole glucosinolates, are impaired in flg22-induced callose and in glucosinolate-dependent restriction of bacterial growth (Clay et al. 2009). Reason: Genetic necessity of CYP79B2/B3 for an antibacterial response mediated by indole glucosinolate breakdown products (CYP81F2/PEN2 pathway). CYP79B3 acts upstream as the first biosynthetic enzyme. Non-core. Supporting Evidence: PMID:19095898 The IGS biosynthetic double mutant cyp79B2 cyp79B3, which completely lacks IGS (21), as well as mutants atr4-1/cyp83B1 and ugt74B1-2, were impaired in the induction of the callose response |
| GO:0044272 sulfur compound biosynthetic process | IEA GO_REF:0000117 | MODIFY | Summary: Sulfur compound biosynthetic process from an ARBA rule, reflecting the CYP79 role in glucosinolate synthesis. Reason: CYP79B3 catalyses the first committed step of indole glucosinolate biosynthesis (Trp to IAOx; the cyp79B2 cyp79B3 double mutant completely lacks indole glucosinolates). The specific term is indole glucosinolate biosynthetic process, which is_a sulfur compound biosynthetic process. Comparator check: the next enzyme, CYP83B1, carries GO:0009759, so the term is applied to the catalysing enzymes of this pathway. Proposed replacements: indole glucosinolate biosynthetic process Supporting Evidence: PMID:15148388 These results demonstrate that only CYP79B2 and CYP79B3 contribute significantly to the IAOx pool from which camalexin and indole glucosinolates are synthesized. PMID:19095898 The IGS biosynthetic double mutant cyp79B2 cyp79B3, which completely lacks IGS (21), as well as mutants atr4-1/cyp83B1 and ugt74B1-2, were impaired in the induction of the callose response |
| GO:0052544 defense response by callose deposition in cell wall | IMP PMID:19095898 Glucosinolate metabolites required for an Arabidopsis innate... | KEEP AS NON CORE | Summary: The cyp79B2 cyp79B3 double mutant is impaired in flg22-induced callose deposition. Reason: CYP79B3 does not deposit callose; it supplies IAOx for indole glucosinolate synthesis, whose 4-methoxy derivative is hydrolysed by PEN2 to signal callose deposition. The requirement is genuine but indirect and context-dependent (Schlaeppi et al. 2010 found wild-type-like callose in cyp79B2 cyp79B3 challenged with P. brassicae). Kept as a non-core upstream annotation. Supporting Evidence: PMID:19095898 The IGS biosynthetic double mutant cyp79B2 cyp79B3, which completely lacks IGS (21), as well as mutants atr4-1/cyp83B1 and ugt74B1-2, were impaired in the induction of the callose response PMID:20230487 we concluded that the lack of IAOx-derived compounds renders Arabidopsis susceptible despite wild-type-like pathogen-induced hypersensitive cell death, stress hormone signaling and callose deposition |
| GO:0090489 tryptophan N-monooxygenase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Tryptophan N-monooxygenase activity from Rhea/EC mapping. Reason: Consistent with the experimentally established activity; recombinant CYP79B3 converts tryptophan to IAOx (Hull et al. 2000). Supporting Evidence: PMID:10681464 We have identified two Arabidopsis cytochrome P450s (CYP79B2 and CYP79B3) that can convert Trp to indole-3-acetaldoxime (IAOx), a precursor to IAA and indole glucosinolates. file:ARATH/CYP79B3/CYP79B3-deep-research-falcon.md found that its membrane extracts converted tryptophan into a product migrating with IAOx, whereas vector-control extracts did not |
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Download this section (compressed HTML)Q: GOA carries only an IEA for tryptophan N-monooxygenase activity on CYP79B3, although Hull et al. 2000 (PMID:10681464) assayed recombinant CYP79B3 directly and CYP79B2 has an experimental row from the same paper. Should an IDA annotation for GO:0090489 be added to CYP79B3?
Q: Where does full-length CYP79B3 reside in planta? An early N-terminal GUS fusion reportedly reached plastids, whereas the paralog CYP79B2 colocalizes with ER-resident CYP71A13.
Q: Does CYP79B3 participate in the ER camalexin metabolon with CYP71A13 and CYP71B15, as CYP79B2 does, or is it mainly a constitutive supplier of IAOx for indole glucosinolates and root IAN?
Q: What fraction of the IAOx pool comes from CYP79B3 versus CYP79B2 in different tissues and stresses, given that CYP79B2 but not CYP79B3 is induced when camalexin synthesis is elicited?
Experiment: Express full-length CYP79B3 fluorescent fusions in Arabidopsis (native promoter) with ER and plastid markers to settle its subcellular location.
Experiment: Determine CYP79B3 kinetic constants and substrate range (Trp versus Phe, Tyr and Trp analogues) with reconstituted P450 reductase, to compare it quantitatively with CYP79B2.
Experiment: Compare camalexin, indole glucosinolate and IAN levels in cyp79b2 and cyp79b3 single mutants after pathogen, jasmonate and salt treatment to quantify paralog-specific contributions.
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