Artificial symbiont replacement in a vertically transmitted plant symbiosis reveals a role for microbe–microbe interactions in enforcing specificity

While these associations, which are often obligatory, suggest very strict recruitment mechanisms, the Dioscorea sansibarensis – Orrella dioscoreae model shows that an aposymbiotic plant can be colonised by other bacteria, revealing a more open ecological niche than expected.

Selection during vertical transmission appears to be essential to the strict specificity observed in nature, highlighting that the stability of these symbioses depends less on initial recruitment than on the locking of the association via transmission—a mechanism that could be generalised to other inherited associations.