Fig. 4

Impact of cultivation temperature on heat resistance, compatible solute profile, transcriptome and proteome of conidia. a, Survival plates of heat-treated conidia that were harvested from mycelium cultivated at 28 °C or 37 °C. Conidia harvested from mycelium cultivated at 37 °C are more heat resistant than conidia harvested from mycelium cultivated at 28 °C in both the wild type and the trehalose deficient strain ∆tpsABC. b, HPLC analysis showing compatible solute composition of conidia cultivated at different temperatures. Conidia of wild type show a significant (p < 0.05 tested with Student’s t-test) increase in the amount of trehalose with cultivation temperature, in contrast to trehalose deficient strain ∆tpsABC. c, Heat inactivation curves of conidia cultivated at different temperatures. Data is based on biological duplicates. D₅₇-values were calculated based on linear regression lines and given in Table 1. d, The transcriptomes and proteomes of dormant conidia cultivated at 28 °C and 37 °C were analysed in order to find candidate genes involved in the observed heat resistance increase when cultivation temperatures are increased. Labels indicate DEGs (green), DEPs (blue) or both (red) comparing 37 °C to 28 °C cultivated conidia. Note that this graph contains only information of 2381 genes, namely genes of which proteome data was obtained, out of in total 11846 genes present on the A. niger NRRL3 genome. Only two genes and their corresponding proteins are significantly more present in the form of transcript and protein in 37 °C cultivated conidia versus 28 °C (NRRL3_04002 and NRRL3_10215). Knock-out strains of NRRL3_04002 and NRRL3_10215 in different backgrounds were grown for 8 days at 28 °C (e) or 37 °C (f) on MEA plates. The heat treatment assay on knock-out strains were measured in biological triplicates