May not be more of a joke than you think, Rick (!). I think the brain analogy has been made with respect to the signals that gut bacteria send to our own brains. I think the metaphor was 'the brain in our guts'.
Sad to think we have been dousing our selves and our food with all these antibacterials: when they (the microbotics) are just what we need to stay healthy and thrive. And plants growing in healthy soil do seem to have some inter signalling capability.
But possibly, rather than trying to find a list of microbiotic species to match up with certain plants, a better strategy is to provide to right conditions, (light, drainage, soil, etc), plant the plants, and then mix up a batch of compost tea, and let the party begin. Plants will attract the right microbiotics for their given situation, and the right microbes from the zillions in the compost tea will obllige.
