Most soil fungi experience a constantly fluctuating environment, and coping with resulting biotic and
abiotic stressors can come at a considerable metabolic cost. We know that organisms respond better to
severe stresses (triggering stress) when they have experienced a similar milder stress (priming stress)
before. Asking how long organisms can remember a priming event is a compelling question. We here
studied priming by temperature stress in filamentous fungi isolated from the same grassland soil. We
hypothesized that filamentous fungi can show priming responses, and that their memory-spans correlate
with their growth rates. Fungal colonies of 19 different filamentous fungi were first primed at 35 C for
5 h (as priming stress) and after 0, 6, 12, 24 or 48 h they were exposed to 40 C for 10 h (as triggering
stress). The variable lag time between the stress applications allowed us to assess memory. Our main
response variable was growth rate. Of the 19 fungal isolates tested, eight showed temperature priming
ability. The Mucoromycotina isolates (Mortierellales) showed a mean growth increase following triggering
stress that was 2.75-fold higher than in unprimed colonies (log-response-ratio). Mucoromycotina
isolates had a memory half-life span (power-law-relationships) of 5.65 h. Considering fungal traits like
growth rate to predict priming responses, we found a positive relationship between priming response
(with 12 h memory phase) and growth rate. The differential ability to be primed in co-occurring isolates
may have direct consequences for fungal communities and coexistence in soil.
© 2016 Elsevier Ltd and The British Mycological Society. All rights reserved