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Just back from the IWEMM8 in France, with plenty of topics to discuss in this Blog. Two new papers help us to understand how black truffle reproduces sexually.
Understanding the sex life of truffles is fundamental to understanding truffle production. Let me remind you that has been found that mycorrhizae and the mycelium that comes from them is always female (positive or negative, but female), and that the male partner of the black truffle has never been found or seen, so we think it could be a dwarf or a temporally partner that does not last in the soil. We have not seen it but by definition it should exist for sexual reproduction to happen.
We knew that black truffle was hermaphrodite (♂ & ♀), so when spores germinated they could become male or female, depending on conditions. I.e. if a positive spore germinates in an area where the mycelium that surrounds, that is always female, is positive as well, then that spore will germinate as a female. But if a positive spore germinates in an area where the mycelium is negative (and always female), then may germinate as a male, so sexual reproduction may happen.
But a new publication from Herminia de la Varga shows that hermaphroditism although is present in black truffle is not the most frequent. There is a male/female specialization as well. So trioecy exists in black truffle.
So female-fertile genotypes as mycorrhizas, and male-fertile genotypes as soil free-living mycelium.
Elisa Taschen group published a parallel paper where they postulate that germlings from the soil spore bank act as paternal partners.
Marcos S. Morcillo
Herminia de la Varga et al. 2016.Investigation of the sexual reproduction strategy of the Perigord black truffle (Tuber melanosporum Vittad.) revealed trioecy.
Taschen et al. 2016. How the truffle got its mate: insights from genetic structure in spontaneous and planted Mediterranean populations of Tuber melanosporum