We just wrote a chapter for a new book that will be published soon about pests and diseases of truffle trees in Spain. We wanted to update the truffle sexuality figure we made for our last book “Truffle Farming Today” with the new discoverings on truffle reproduction, and you can see here the new one!
In a mature truffle plantation, at a root level, there is a non-random distribution of the MATs (sexually compatible mycelia), that is, the mycorrhizae of a tree tend to belong to the same MAT.
Moreover, the mycelium that forms the mycorrhizae acts always as a maternal part.
In the enlargement it is observed how the truffles are formed, mostly, when a spore germinates and the mycelium acts as a paternal part fertilizing the maternal mycelium associated with a mycorrhiza of the complementary MAT.
We talked in an earlier post about how in some large multilobulated fruit bodies, each lobe belongs to a different paternal individual, that mostly comes from truffle spores.
Most truffles are formed sometime between May and July. It seems that at more latitude (colder areas), fertilization occurs later. But do we know how many baby truffles get formed per square meter? you´ll get surprised to know that a new research not published yet found, sieving the soil, that 104 truffle primordia were found per m2!
Unfortunately, most of these baby truffles get eaten by insects, dry up or get rotten before they mature properly.
This has been done by Pacioni, the same author who used the ground penetrating radars to screen the soil looking for baby truffles.
Cheers,
Marcos S. Morcillo
References:
Pacioni G et al. 2014 Instrumental monitoring of the birth and development of truffles in a Tuber melanosporum orchard. Mycorrhiza.
trufflefarming 
Nice to see continued new discoveries and information sharing!
thanks for following Adam! Happy New Year!