Drought stress priming in filamentous saprotrophic fungi: transcriptomic/proteomic responses and the impact on C mineralisation
Final Report Abstract
Sessile organisms constantly face environmental fluctuations like drought. One adaptive mechanism is “stress priming”, the ability to cope with a severe stress (“triggering”) by retaining information from a previous mild stress (“priming”) after a recovery phase. While plants have been extensively investigated for drought-induced stress priming, no information is available for filamentous saprotrophic fungi, which are highly important for nutrient cycles, or microbial communities. Here, we investigated the impact of drought-induced stress priming I.) with varying recovery durations on two ubiquitous species, Neurospora crassa and Penicillium chrysogenum; II.) on microbial communities in A-horizons of a European beech and Norway spruce forest; III.) on the transcriptomic response of Agaricus bisporus. Four treatments were conducted in all cases: priming (pF 4) and/or triggering (pF 6) as well as non-stressed controls. I.) P. chrysogenum showed positive stress priming effects. After 1 day of recovery, biomass as well as β-glucosidase activity were 5 and 0.5 times higher, respectively, during triggering. Effects on biomass and activity decreased with prolonged recovery but lasted for 7 days. For N. crassa, no stress priming effect was observed. II.) In the beech soil, microbial biomass was about 0.7 times higher after priming during triggering. No community shift was observed and Mortierellomycetes dominated the fungal community. In the spruce soil, stress priming had only minor effects during triggering. However, biomass was increased about 0.5 times without triggering. Further, priming and triggering lead to a shift in community composition. Noticeable was a strong increase with or a reduction without triggering, probably due to the high cost of the priming, in mean abundance of Byssonectria fusispora. Priming without triggering increased mean abundances of Mortierellomycetes. III.) On the transcriptomic level of A. bisporus, stress priming seems to lead to an upregulation of factors regulating translation, transcription, and DNA replication. In contrast, factors associated to DNA and protein repair seem to be down regulated in comparison to non-primed samples allowing primed hyphae to remain a higher respiratory activity after the triggering. Overall, the potential for drought-induced stress priming can be found in saprotrophic filamentous fungi. Yet, it seems to be species specific with potentially high impact on fungal communities. Stress priming can stimulate microbial soil biomass and shift the community depending on the original community and the occurrence of a triggering event. The regulation of stress priming responses seems to be based on epigenetic factors like translation and transcription factors.
Publications
- Assessment of prokaryote to eukaryote ratios in environmental samples by SSU rDNA length polymorphism. Antonie van Leeuwenhoek 113, 175–183
Guhr, A., Weig, A.R.
(See online at https://doi.org/10.1007/s10482-019-01327-y) - Drought-Induced Stress Priming in Two Distinct Filamentous Saprotrophic Fungi. Microbial Ecology 80, 27–33 (2020)
Guhr, A., Kircher, S.
(See online at https://doi.org/10.1007/s00248-019-01481-w)
