2a). The cp transcript amount was lower in almost every condition BAY 57-1293 compared with the corresponding control, showing a down-regulating effect of the stress factors on the expression of the cp gene. Specifically, when compared with the growth on PDA at 25 °C (control 1), the cp gene expression was down-regulated
by low temperature (15 °C), osmotic water stress (caused by NaCl or glycerol added to PDA) and growth on the sawdust-agar media. It was also down-regulated when H2O2 or umbelliferone was added to the medium in comparison with the respective controls 2 and 3 (growth in PDB in vials or flasks, respectively) and finally during the co-culture with T. atroviride or T. harzianum compared with the C. platani/C. platani co-culture (control 4). On the other hand, the cp transcript amount was higher than control under matric water stress caused by PEG 8000 and when the culture was maintained static, whereas at 32 °C the increase was not significant. At the same time, most conditions also reduced the growth of C. platani as compared with the respective controls (Fig. 2b). Fungal growth increased only at a temperature of 32 °C and in static culture, although the latter increase was again not
significant. Therefore, the amount of cp transcript was strictly related to the growth level of the fungus: in all those conditions that reduced the growth of C. platani, the cp transcript level was lower
than the control. The only see more exception was represented by the matric water stress, where the cp transcript level increased while fungal growth was reduced. The effect of the different growth conditions on conidiogenesis in C. platani was evaluated by analysing the production of both conidia and chlamydospores (Table 1). Conidia were generally formed in all the conditions studied, although in different amounts; Reverse transcriptase with NaCl or PEG 8000, however, no conidia were present. In particular, they were produced in large amount on the sawdust-agar media where the cp transcript level was reduced and not formed under matric stress where cp was upregulated. No relation could therefore be found between conidia formation and cp gene expression. On the other hand, the highest production of chlamydospores was observed where cp was up regulated, including the matric water stress (Fig. 3 and Table 1), suggesting that the cp transcript level could be related to chlamydospores production, despite the reduction in growth. As chlamydospores could not be detached from hyphae, to test this hypothesis, C. platani was inoculated on PDA plates amended with PEG 8000, and chlamydospores differentiation, cp gene expression and fungal growth were investigated at 2, 3 and 4 days post-inoculation.