This shared morphology might represent an adaptation to growing near active resin flows: the perennial ascocarps can effectively rejuvenate in situations where they happen to be partly submerged in fresh exudate. All three species commonly live on cankers and wounds which exude resin over extended periods. It seems unlikely that the ascomata of resinicolous Chaenothecopsis species could rejuvenate after being rapidly and completely submerged
in fresh sticky resin. Even the fossil specimens had first produced fruiting bodies on hardened resin and then Doramapimod ic50 had subsequently been covered by a thick layer of fresh exudate. This raises the question of what then triggers the proliferation in partly submerged ascocarps and those ascocarps only growing close to fresh resin. It has been shown that some fungi react to the volatile compounds produced by other fungi when competing for resources (Evans et al. 2008). It is also known that fresh resin contains high levels of volatile compounds, mainly monoterpenes and sesquiterpenes, when compared to older, semisolid exudate, and that the hardening of resin is directly related to the loss of such compounds (e.g. Langenheim 2003; Ragazzi and Schmidt 2011). An ability to detect and respond to the presence of volatile resin compounds in the environment would give the Chaenothecopsis
species time to prepare for a potential burial in freshly exuding resin. It seems feasible that some resinicolous fungi could begin to branch when the concentration of volatile resin compounds in their typically sheltered microenvironment Selleckchem TH-302 is sufficiently high as to indicate that a fresh resin flow may be imminent. In other fungi the differentiation of fruiting bodies is commonly triggered by the perception of some change in environmental conditions, such as light, pH, 4��8C oxygen etc. (Busch and Braus 2007). The hyphae of extant resinicolous fungi commonly penetrate and grow into semisolid resin. Evidence
of inward growth of fungal hyphae is also preserved in numerous worldwide amber fossils since the Paleocene (Temsirolimus personal observation), but no evidence of a similar capability has yet been found prior to the Cretaceous-Paleogene boundary. Cretaceous amber pieces from several different deposits may contain abundant filaments that grew from the resin surface into liquid resin, but all of these have been identified as filamentous prokaryotes (see Schmidt and Schäfer 2005; Schmidt et al. 2006; Girard et al. 2009a, b; Beimforde and Schmidt 2011), not as fungal hyphae. This suggests that this special niche was either occupied by prokaryotes in the Mesozoic or that Chaenothecopsis species (if already existent) and other ecologically similar fungi did not yet exploit resin substrates. Conclusions Fossil evidence of inward growth of fungal hyphae into plant exudates has not been identified from Mesozoic ambers, suggesting a relatively late occupation of such substrates by ascomycetes.