Biochemical adaptation of phytopathogenic fungi, Sclerotium rolfsii, in response to temperature stress

Abstract

Temperature stress plays a critical influence on microbial survival and ecology. It has been reported to be associated with direct effects on microbial metabolisms, but there are very few studies in literature which have reported it in phytopathogenic fungi. In this study, we investigated the impact of two different temperature conditions, 28 and 32°C on the changes of Sclerotium rolfsii cellular components using Fourier transform infrared (FT-IR) spectroscopy and enzyme activities measurement. Our results demonstrate that growth, sclerotia germination and biomass of S. rolfsii were obviously increased at 32°C. The changes in defense enzymes activity as peroxidase (POX) generally decrease and changed at 32°C. Moreover, the culture of S. rolfsii grown at 32°C shows the higher content of the lipid content as shown in the spectral regions of CH stretching and bending bands, when compared with those of this fungi culture under temperature at 28°C, indicating that these indicators played a role in biochemical adaptation in S. rolfsii, probably due to enhanced activity of the fungal metabolism pathway and cell wall/membrane protection to temperature stress. Our findings illustrate that temperature stress caused increase biomass and lipid composition; whereas decrease in POX activities, which is a key enzyme helps S. rolfsii cope with survival at higher temperature.

Key words: Sclerotium rolfsii, enzyme activities, stress response, cellular composition, FT-IR spectroscopy.