Endophytes

[reed]

I remember that whiteish appearance on the leaves that used to show up later in the season sometimes, I'll assume powdery mildew is what it was. Don't see it so much anymore since some kind of stink bug showed up several years ago. They come in mass all of a sudden and can kill a plant almost overnight. When little, they cluster on the underside of the leaves so by inspecting frequently and squishing them it's still possible to harvest some fresh young summer squash.

Wish I had more space, I could just plant big patches and wait but I figure it would probably take acres and hundreds or thousands of plants to pull it off.
 

[Steph S]

Thinking about seed dispersal is very thought provoking.  Where animals/birds are involved, it raises questions about our own skin microbiome, for example, and how that interacts with that of the seed.  I believe our healthy skin biome with organisms like yeasts and lactobacilli is benign to seeds.  The farmer who's been weeding or spreading compost likely has some of those organisms on the hands as well... 
In past reading about tomato seed fermentation vs other methods, seed treatments and their possible consequences, I learned that the microbiome around a germinating seed is one where the community structure changes rapidly and by the time the plant emerges, is entirely different from the start.  The subtlety and complexity of interactions that are so transient may be beyond my grasp but yet I still think they are important, in facilitating that community revolution from seed to seedling endpoint. 
Unless you were just handling diseased material at planting time, the worst situation for a seed is where sterilants have been used to clear the whole microbiome.  This is exactly the situation where "opportunistic" pathogens can do their worst.
Inoculants are probably a good idea in that case.  But the presence of endosymbionts in the seed tissue itself is something I hadn't considered.  That has to be a plus, and most likely if the seeds came from plants grown in healthy soil with compost.

[Steph S]

Here is a recent review of the current work being done on endophytes, with bibliography links to articles.
https://www.tandfonline.com/doi/full/10.1080/21501203.2021.1945699

There is apparently some debate about classification, and how pathogens should be termed vs symbionts, since both can be indwelling in the plant.
Also makes the difference about "horizontal" (air, water, other vector) vs "vertical" (up through the plant) transmission.

"Horizontal transmission occurs when vegetative propagules or spores are produced by
the endophyte and spread to the plant population through the air or via some vector,
while vertical transmission consists of the transference of the fungi to the plant
progeny via seeds (Gimenez et al. 2007; Aly et al. 2011; Lugtenberg et al. 2016)."

"Apparently, vertically transmitted fungi seem to present plant associations with a
more mutualistic profile than horizontally transmitted fungi, which are more likely
antagonists (Aly et al. 2011)."

From an ethical standpoint, this would favor inclusion of seed borne endophytes, and possibly inoculum from compost or soil, but not inoculation with exposed aerial parts such as pods or leaves.
Even on a home scale, it would be easy to experiment with compost dusting of seeds before planting.  Granted that the same seeds from plants grown in the compost would, in theory, already have acquired endophytes in the process.  So the question, would the dusting make a difference to home grown seed vs seed acquired from a seed bank or commercial source where sterilant has been applied, or is recommended to avoid introducing seedborne pathogens.

[Steph S]

Just wanted to add, I was wrong to exclude viruses, apparently. 
Mycoviruses can affect those endophytes that are pathogenic, and cause hypovirulence.  ie  the Botrytis or Sclerotinia is no longer acting as a pathogen, because of a virus incorporated into the fungal genome.

https://pubmed.ncbi.nlm.nih.gov/23498902/

A botrytis example:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8309985/
A sclerotinia example:
https://www.sciencedirect.com/science/article/pii/S1674205220302938

[clweeks]

Super-cool topic, and it's funny how things come in waves. Last week I watched six hours of video of Dr. Christine Jones on polyculture and she talked about plants making endophytes of soil microbes and I think that's maybe my first real exposure to the idea. And then yesterday I read the post by Julia on Permies about your course with the extensive quotes by Dr. James White. And now you're talking about it here.

A question though; if the following is true, do you really need to distribute soil with the seeds?

Endophyte spores are typically incorporated into the seeds by the plants, either by depositing onto the cell coat, or internally.

You asked what we'd like to see in the course. I haven't done a review of literature, is there a lot? If there isn't, then it isn't even possible to provide too much. So give it all to us. Digest the research and summarize the state of the art in the course material. Particularly if you've done testing/research yourself, though I'm not sure what that would look like.

I guess an interesting study would be to send four seeds and some of your soil to several different people in various climates, have them grow them in containers, but half in your soil and half in theirs, trying to minimize effects from any other confounding variables. Or maybe grow one in pure Paradise soil, one in 2/3 Paradise soil, one in 1/3 Paradise soil, and one in pure local soil and see what the effect is. If they all grow about the same, regardless of how well, climate is probably a bigger factor than soil biota. If not, not. It certainly would color the way we think of landrace development.