Comment by krisoft | Hacker News Reader

Comment by krisoft | Hacker News Reader

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We do know how truffles reproduce. It's on wikipedia [1]

"Because truffle fungi produce their sexual fruiting bodies under ground, spores cannot be spread by wind and water. Therefore, nearly all truffles depend on mycophagous animal vectors for spore dispersal."

The truffle is full of spores. Because it is underground it can only spread far if something or someone digs it up and tries to eat it.

"When the ascospores are fully developed, the truffle begin to exude volatile compounds that serve to attract animal vectors."

The truffle smells good so something or someone finds it and digs it up.

The trick is that humans only care about a few species of mushrooms as truffles. You spread the spores of one of these good species around the roots of a tree sapling you plant and then you hope that it will establish a good healthy colony. If for any reason some other mushroom species outcompetes your truffle species you won't have any truffles. And it takes multiple years to know if that happened or not. So any experimentation in finding the right method or the right conditions to promote the truffle species and discourage the other species goes at a snail's pace.

1: https://en.wikipedia.org/wiki/Truffle#Ecology

If someone would want to invest a crazy amount of money to accelerate this discovery process I can imagine two things we could do: (don’t do it, it is a bad idea)

- we could make a genetically modified truffle fungi which glows in the dark. Now, why would that help? The problem with monitoring the health of your fungi is that most of the body mass of it is in the form of tiny thread like stuff called mycelium. Even if you take a soil sample it is kinda hard to tell the mycelium of the right species apart from the wrong ones. With some species experts can tell them apart under microscope but the only sure way to tell what fungi’s mycelium you are looking at is to DNA sequence it. Which is expensive thus rarelly done. But if you could make your target specie glow under UV light it would make the analysis that much simpler and cheaper. So we could do it more often and thus learn about what factors favour our truffle faster.

- The other option would be to engineer a kind of “immune system” to our truffle species. Basically to make “nanobots” which leave our truffle but kill other fungi. Now how on earth would one do something like that? I would start by trying to modify mycoviruses (the kind of viruses which attack fungi). Many of them are already quite picky about what kind of fungi they infect, so probably that would help us. Bonus points if we can engineer the virus such that it dies out in nature after a few rounds of reproduction so we can minimize the chances of an escape.

Of course both of these ideas are very speculative, scifi level conceptual stuff. :)

what a great time for novel gain of function research on obscure viruses.

Death by genetically enhanced, unstoppable fungi which grow in the lungs, and nose.

Truffled to death.

Cheesed to meet you

Isn't this the plot of The Last of Us?

Actually, in the brain, yeah. And a well thought out plot, too.

I remember looking at old newspapers in the game, and it looks like the fungus was on crops. And I think there were allusions that the fungus was the same on which controls ants, but mutated.

Very fun game.

But your infected lungs will be very simple and cheap to analyze, because they will glow in the dark.

I was thinking more of a "point an ultrasonic imager at the dirt" kind of solution. There's got to be some way to see what's going on before nine years!

Yeah, but the problem is that you will have fungi. It is basically guaranteed. What you care about if it is the right kind.

A PCR test of your soil sample will be very specific and very sensitive.

> Bonus points if we can engineer the virus such that it dies out in nature after a few rounds of reproduction so we can minimize the chances of an escape.

This should be a top priority or you're describing the beginning of the next disaster/distopian movie.

Oh yes. That whole thing is better to be left alone, or used as a plot point in a novel as you say :)

Life uh, finds a way.

bioilluminescent truffles sounds like a really good idea to me

From what I understand, a complex symbiosis is required for truffle mycelia to flourish, so the immune system idea might backfire by killing beneficial organisms similar to how antibiotics can kill beneficial bacteria in the human body.

Even worse idea, but much more realistic:

-add a fungicide resistance gene into your truffle strain. Inoculate your tree with this GMO strain, treat the soil regularly with appropriate fungicide. This will kill off the competing fungi, leaving only your strain.

I have a hunch that wouldn't work well. Trees often use more than one type of mycorrhizal fungi, and there's a lot we don't know about why, how, what causes the mycelium to start the production of fruiting bodies etc.

Not to worry, they will simply use a low dose, enough to slow down the competing fungi, breeding fungicide resistance in the process.

Even then, figuring out what’s needed to make it grow _and_produce_truffles_ may be challenging. There are lots of variables. Temperature/humidity/acidity of the ground/availability of nutrients/… throughout the year all may matter.

Possibly, that’s even throughout the yearS. Mast happens “at irregular periods of 2–12 years” (https://en.wikipedia.org/wiki/Mast_(botany)) and we don’t really understand that, either.

There are degrees to how, and much is still unknown. As you point out, much of the unknown how relates to propagation and symbiotic bonding to the host trees and soil biology.

You are very right. I choose to pursue other mysteries in my time here on Earth, but it would be so exciting getting to know everything there is to know about the mycorrhiza. Even just reading the literature to learn what others already know would take a long time. Sometimes I feel life is too short.

Ps: Excelent work on the fjords, they turned out really pretty.

Yup. We don't have human-edible truffles around where I live (west coast of Norway), but it is possible to find deer truffles, unrelated fungi with a similar strategy. They release pheromones which make deer go a bit crazy. Apparently they used to be sold in apothecaries as "rutting balls" (løpekule), aphrodisiac for cows basically.

>>And it takes multiple years to know if that happened or not

Couldn't you just do some chemical analysis to verify if your desired fungi is present in the roots?

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