I've also got a poster (#9) if you want to discuss further details.

Tokyo waterworks museum, pretty small but it's worth a look around

Not sure if there's some relationship to raccoondogs or if it's just an artistic predeliction for the scrotum as a weapon

Probably the direct binding of PHRL7 overrules the more general KL signalling of nutrition, but it wouls be interesting to see if in the legumes KL signalling is more dominantly regulated by nitrogen status.

Wondering how this fits with SMAX1 - at least in Glycine it appears to inhibit nodulation, and is degraded downstream of PHR (in Arabidopsis & rice).

( @oswaldovaldesl.bsky.social )

Thanks, glad my rambling made some sense. Not sure I'm enough into phylogenomics to write that review, but @alexdallaire.bsky.social might have a more informed take.

There are plenty of extant fungi that range from pathogenic to mutualistic depending on the environment too, trying to categories things beyond 'capable of intimate metabolic association' may be looking at it wrong.

Some people think there is a geologically regular switch between pathogenesis and symbiosis in the EcMF linages, but thats disputed and not well evidenced.

For the review's scenario, I guess you could have a fungi terrestrialised to grab lithic minerals, and reaches back to water to pull carbon from aquatic macroalgae? Seems possible but IDK how likely.

Aquatic to terrestrial transition of lichens makes a lot of sense, but we're looking at different linages for plant/mycorrhiza. Geosyphon & Mortierella are both reported to have endosymbiotic algae, which would be another route, but again doesn't match plant phylogeny emerging from a macroalgae.

Increased access to minerals may also be sufficient, though you'd think if this was the case you'd be able to find mycorrhizal-like associations in extant macroalgae

with partially terrestrial filamentous fungi foremost for providing hydraulic conductivity, but TBH glomeromycotina genomes are so reduced we could just be missing some service an aquatic ancestor could have provided (like some extant vitamin exchange cycles between algae & fungi in their CW).

rather than a commensal & it would seem quite likely symbiosis precedes terrestrialisation. Though you do have the question of what the aquatic fungus provided.
I could also conceive of the first plants being an interaction between algae in intermittently dried fresh water,

I'd missed that line (early land plants tamed some of their attackers, leading to mutually beneficial AM relationship) in the review, IMO better to see evolution to symbiosis is really a two-way street.

I don't think we have evidence that the first mucoromycota symbiont was a pathogen

I think we can also hypothsize two waves of autotroph-fungal terrestralisation, first of ascomycete - algal (lichen) and then of mucoromycota - plants (Honegger 2012, though again the fossil evidence isn't old enough to differentiate)

On the plant side, chareles seem to have most of the core symbiotic geneset but I don't know of any known fungal symbiont of them, or even to what extent its been investigated - though land plant fossils predate fossil chareles so what their LCA was is also purely inferred from phylogenomics

It makes sense to me that Mucoromycotan symbiosis would arise from an fungus that associated with an alga either pathogenically or sapotrophically on waste or dead cells, but at this point I don't know how you'd tell that apart.