|Guhr, A; Horn, MA; Weig, A: Vitamin B2 (riboflavin) increases drought tolercance of Agaricus bisporus, Mycologia, 109, 860-873 (2018), online: 2018-02-26, doi:10.1080/00275514.2017.1414544 [Link]|
Drought is a stressor for many soil inhabiting organisms. While plants have been extensively investigated for drought adaptive mechanisms, little information is available for fungi. Antioxidants are especially relevant, since desiccation is accompanied by an excessive intracellular production of reactive oxygen species. Riboflavin (vitamin B2) is an antioxidant regulating drought tolerance in plants. A similar function may exist in fungi. Here, we examined the respiratory and transcriptional response of Agaricus bisporus to drought and the impact of riboflavin. Mesocosm experiments with 4 groups were established: hyphae were treated with or without 50 μM riboflavin under drought or no drought conditions. Drought increased riboflavin content in hyphae about 5 times with, but also without riboflavin addition. Without riboflavin addition, fungal respiration decreased by more than 50% at water potentials of about -20 MPa. With riboflavin addition, respiration remained about 2-3 times higher. The transcriptional response to only drought or riboflavin strongly overlapped and was mainly based on factors regulating transcription and translation. This was even stronger in combined treatments. Riboflavin induced protective mechanisms in drought stressed hyphae. Most pronounced was the methylglyoxal (cytotoxic by-product of glycolysis) detoxifying lactoylglutathione lyase. Thus, our data suggests a stress priming function and a prominent role of riboflavin in drought responses of A. bisporus.