Iron-sulfur cluster biogenesis — ISC, SUF and CIA. Every Fe/S node on QBM-01, QBM-02 and QBM-05 depends on one of these three systems, so a defect here sits upstream of the whole atlas and would appear as a metabolic lesion well before any visible phenotype. Read the tiers carefully, because they mark a distinction that is easy to blur: the near-null-field evidence in this area (Islam 2020, Vigani 2021, Narayana 2018) measured iron UPTAKE and Fe-S interplay — nutritional physiology — and is attached to the Fe/S supply node, which is therefore T2. No experiment in the bibliography applied a magnetic field and measured cluster assembly itself, so every assembly node remains T3 no matter how attractive the mechanism looks. The single arrow from mitochondrial export to the CIA system is the reason this map reaches beyond bioenergetics: CIA clients include the DNA replication and repair enzymes, so a mitochondrial lesion propagates to genome maintenance. Derived from: Figure 3 panel B of Porterfield & Barker, "Plant Responses to Near-Null Magnetic Fields" — expanded to the three assembly systems and bound to Arabidopsis loci structural_context CHEBI:29033 CHEBI:29034 CHEBI:16189 The geomagnetic field contributes to efficient iron uptake in Arabidopsis; reducing it to near-null affects root metal reductase activity. Geomagnetic-field-dependent modulation of iron-sulfur interplay in Arabidopsis, most pronounced under combined Fe and S deficiency. Reduction of the geomagnetic field to near-null affects Arabidopsis root mineral nutrition. Note carefully what the cited work does and does not show. Islam 2020 and Vigani 2021 measured iron uptake and Fe-S interplay under altered field conditions — nutritional physiology. Neither measured cluster assembly. This entity is T2 because the field effect is demonstrated for the process it names; the assembly entities above remain T3 because that evidence does not reach them. structural_context AT5G65720 2.8.1.7 iron_sulfur_2Fe2S 57Fe 33S AT4G22220 Holds a transient, solvent-exposed [2Fe-2S] cluster whose assembly involves iron redox chemistry and sulfide transfer. A nascent cluster on a scaffold is more exposed and shorter-lived than a mature one buried in a protein, which makes it a more credible point of perturbation than the finished product. Entirely untested. No experiment has measured scaffold occupancy or transfer rate under any magnetic field condition. structural_context AT4G03240 Frataxin is localised to both chloroplast and mitochondrion and is involved in chloroplast Fe-S protein function in Arabidopsis. iron_sulfur_2Fe2S 57Fe 33S AT5G06410 AT3G15660 GRXS15 binds a bridging [2Fe-2S] cluster in its dimeric form, so the cluster is genuinely in transit and solvent-accessible here rather than buried. iron_sulfur_4Fe4S 57Fe 33S AT3G20970 AT1G51390 Transiently hold clusters destined for aconitase, succinate dehydrogenase and lipoyl synthase — precisely the QBM-01/QBM-05 nodes the review nominates. If assembly were field-sensitive, this is the step that would show it first. structural_context AT5G58270 Cytosolic Fe/S protein biogenesis depends on export of a sulfur-containing intermediate from the mitochondrion. iron_sulfur_4Fe4S 57Fe 33S AT1G08490 AT4G26500 Builds every cluster in the chloroplast, including PSI's FX/FA/FB and ferredoxin's [2Fe-2S]. It is the single upstream dependency of QBM-02's strongest nodes. iron_sulfur_4Fe4S 57Fe 33S AT3G24430 The chloroplastic NifU-like protein CnfU can act as an Fe-S cluster scaffold and is required for biogenesis of ferredoxin and photosystem I. The review names CnfU explicitly: Yabe et al. showed the chloroplastic NifU-like protein acts as a scaffold and is required for photosystem I biogenesis, which makes it the direct upstream dependency of QBO:PSI_FES. iron_sulfur_4Fe4S 57Fe 33S AT5G50960 AT4G16440 AT2G26060 AT1G68310 AT5G48120 The reason this map matters beyond bioenergetics: CIA clients include the enzymes of DNA replication and repair, so an assembly defect reaches genome maintenance, not just ATP supply. iron_sulfur_4Fe4S iron_sulfur_2Fe2S 57Fe 33S AT4G35830 AT5G66760 AT5G13430 AT4G03280 AT1G10960 AT2G20860 AT2G21790 Collected here so the map can show, in one edge, that a single assembly defect reaches respiration, photosynthesis, the TCA cycle, nitrogen and sulfur assimilation and DNA replication simultaneously. That breadth is the review's argument for why Fe/S biology deserves attention ahead of cryptochrome. direct_influence direct_influence direct_influence cofactor_insertion cofactor_insertion cofactor_insertion cofactor_insertion cofactor_insertion direct_influence direct_influence cofactor_insertion cofactor_insertion cofactor_insertion indirect_influence