The Mycelial Inheritance

From the Lesson

THE MYCELIAL INHERITANCE — HOW FUNGI & PLANTS GREW FROM MINERAL TEMPLATES

The previous lessons established that life originated in serpentinized rock and that no hard boundary separates mineral chemistry from biology. This lesson follows the thread forward in time — from the deep biosphere chemolithotrophs to the emergence of fungi, plants, and ultimately the entheogenic species explored in the Ethnobotany series. The argument is simple and radical: fungi and plants did not merely evolve "on" the Earth. They evolved from the Earth's mineral-chemical templates, and they still carry those templates in their deepest biochemistry.

THE FIRST COLONISTS: FROM VENT TO LAND

When life first emerged from alkaline vents approximately 4.0–4.2 billion years ago (Dodd et al. 2017, Nature 543:60–64, reported possible biogenic structures in 4.28 Ga ferruginous sedimentary rocks from the Nuvvuagittuq greenstone belt, Quebec), it faced a fundamental constraint: it was tethered to the hydrogen supply of serpentinization. The earliest organisms — methanogens, acetogens — could not survive far from their mineral nursery. They were, in a real sense, extensions of the rock.

The great liberation came in two stages:

Stage 1 — Photosynthesis (~3.5–2.7 Ga):

The evolution of oxygenic photosynthesis was the most consequential biochemical innovation in Earth history. Cyanobacteria evolved the ability to split water (2H₂O → O₂ + 4H⁺ + 4e⁻) using sunlight, replacing H₂ gas as the electron donor for carbon fixation. This reaction liberates 1.23 eV per electron (at standard conditions) — enough to drive the entire photosynthetic apparatus.

But the molecular machinery was not invented from scratch. The oxygen-evolving complex (OEC) at the heart of Photosystem II — the engine that splits water and releases the oxygen we breathe — is a cluster of four manganese atoms and one calcium atom bridged by five oxygen atoms: Mn₄CaO₅, arranged in a distorted cubane structure with a "dangler" Mn atom (Umena et al. 2011, Nature 473:55–60, resolved to 1.9 Å by X-ray crystallography).

This structure is virtually identical to the mineral ranciéite ((Ca,Mn²⁺)Mn⁴⁺₄O₉·3H₂O), a manganese oxide found in serpentinite-associated weathering environments and manganese nodules on the deep seafloor (Post 1999, PNAS 96:3447–3454). The Mn-Mn distances in the OEC (2.7–3.3 Å) match those in ranciéite within 0.1 Å.

Vitaly Ananyev and G. Charles Dismukes (Rutgers University) demonstrated experimentally that synthetic manganese-calcium oxide clusters (Mn₄Ca) can perform water-splitting photochemistry — generating O₂ from water under UV illumination — without any protein scaffold (Ananyev et al. 2005, JACS 127:4306–4307; Dismukes et al. 2001, PNAS 98:2170–2175). The mineral alone can do it.

Photosynthesis is a mineral reaction that biology learned to carry in a protein wrapper. The protein (D1 subunit of PSII, 353 amino acids) provides fine-tuning, protection from photo-oxidative damage, and coupling to the rest of the photosynthetic electron transport chain. But the catalytic heart — the water-splitting Mn₄CaO₅ cluster — is a piece of geological mineral, inherited from the serpentinized seafloor.

Stage 2 — Terrestrialization (~470–450 Ma):

When the first organisms colonised land during the Ordovician period, they did not do it alone. The oldest fossil evidence of terrestrial life — from the Ordovician Cooksonia flora and associated microfossils — shows fungal hyphae intimately associated with the earliest land plant ancestors (Redecker et al. 2000, Science 289:1920–1921, identified Glomus-type arbuscular mycorrhizal fungi in 460 Ma fossils from the Ordovician of Wisconsin).

The reason is chemical: bare rock contains no bioavailable phosphorus, nitrogen, or trace metals in forms accessible to plant roots. Fungi — specifically, the ancestors of modern arbuscular mycorrhizal (AM) species (phylum Glomeromycota) — could extract these nutrients from rock through acid-dissolution chemistry:

• Fungal hyphae secrete organic acids (oxalic acid, C₂H₂O₄, at concentrations up to 20 mM; citric acid, C₆H₈O₇, up to 5 mM) that dissolve silicate minerals (Landeweert et al. 2001, Trends in Ecology & Evolution 16:248–254).

• The dissolution rate of feldspar by oxalic acid is 10–100× faster than by water alone at pH 3–4 (Welch and Ullman 1996, Geochimica et Cosmochimica Acta 60:2939–2948).