Abstract
High temperature is a key limiting factor for mycelium growth and development in Pleurotus ostreatus. Thermotolerance includes the direct response to heat stress and the ability to recover from heat stress. To better understand the mechanism of thermotolerance in P. ostreatus, we used morphological and physiological analysis combined with an iTRAQ-based proteomics analysis of P. ostreatus subjected to 40°C for 48 h followed by recovery at 25°C for 3 days. High temperature increased the concentrations of thiobarbituric acid reactive substances (TBARS) indicating that the mycelium of P. ostreatus were damaged by heat stress. However, these physiological changes rapidly returned to control levels during the subsequent recovery phase from heat stress. In comparison to unstressed controls, a total of 204 proteins were changed during heat stress and/or the recovery phase. Wherein, there were 47 proteins that responded to both stress and recovery conditions, whereas 84 and 73 proteins were responsive to only heat stress or recovery conditions, respectively. Furthermore, quantitative real-time PCR (qRT-PCR) confirmed differential expression of nine candidate genes revealed that some of the proteins, such as a mitogen-activated protein kinase (MAPK), phenylalanine ammonia-lyase (PAL), and heat shock protein (HSP), were also regulated by heat stress at the level of transcription. These differentially expressed proteins (DEPs) in mycelium of P. ostreatus under heat stress were from 13 biological processes. Moreover, protein–protein interaction analysis revealed that proteins involved in carbohydrate and energy metabolism, signal transduction, and proteins metabolism could be assigned to three heat stress response networks. On the basis of these findings, we proposed that effective regulatory protein expression related to MAPK-pathway, antioxidant enzymes, HSPs, and other stress response proteins, and glycolysis play important roles in enhancing P. ostreatus adaptation to and recovery from heat stress. Of note, this study provides useful information for understanding the thermotolerance mechanism for basidiomycetes.
Highlights
Pleurotus ostreatus, known as the oyster mushroom, is the third largest edible fungus produced in China
Previous studies exploring P. ostreatus response to high temperatures have only focused on physiological changes including cell programmed death (Song et al, 2014), cell membrane stability (Kong et al, 2012), mycelial micromorphology, and antioxidant systems (Meng et al, 2015), but few studies to date have investigated the changes in protein expression induced by heat stress during the thermotolerance response
The results showed that the differentially expressed proteins (DEPs) identified in the mycelium under heat stress and recovery were primarily involved in cellular, metabolic, multi-organism, reproductive, and developmental processes; biological regulation; localization; nitrogen utilization; cellular component organization or biogenesis; reproduction; response to stimulus; signaling biological processes, whereas
Summary
Known as the oyster mushroom, is the third largest edible fungus produced in China. P. ostreatus is highly valued for its superior texture, flavor, and nutritional quality as well as its demonstrated antioxidative, hypocholesterolemic, and antiatherogenic activities (Anandhi et al, 2013), antitumor properties (Jedinak and Sliva, 2008), and its ability to enhance the immune system (Jesenak et al, 2013). It is one of the most widely cultivated and consumed edible mushrooms in China due to its short growth time, high adaptability, and productivity. Previous studies exploring P. ostreatus response to high temperatures have only focused on physiological changes including cell programmed death (Song et al, 2014), cell membrane stability (Kong et al, 2012), mycelial micromorphology, and antioxidant systems (Meng et al, 2015), but few studies to date have investigated the changes in protein expression induced by heat stress during the thermotolerance response
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