Abstract
Heat stress is an important adverse environmental stress that influences the growth and development of Hypsizygus marmoreus (white var.). However, the molecular basis of heat stress response in H. marmoreus remains poorly understood. In this study, label-free comparative proteomic technique was applied to investigate global protein expression profile of H. marmoreus mycelia under heat stress. Confocal laser scanning microscope observation revealed that mycelia underwent autolysis and apoptosis under heat stress. Autolysis was mediated by upregulating the expression of cell wall degradation enzymes and inhibiting cell wall synthesis enzymes, and apoptosis might be induced by ROS and activation of caspases. TBARS analysis indicated that ROS was accumulated in H. marmoreus mycelia under heat stress. H. marmoreus induced antioxidant defense system by upregulating the expression of catalases, superoxide dismutases and peroxidases to prevent oxidative damage. MAPK cascade was found to be involved in heat stress signal transduction. The stress signal induced a ubiquitous defense response: inducible expression of different kinds of heat shock proteins. Trehalose synthesis enzymes were also upregulated, suggesting the accumulation of stress protector trehalose under heat stress. Besides, upregulated proteasome was identified, which could prevented the accumulation of non-functional misfolding proteins. To satisfy ATP depletion in heat response cellular processes, such as ROS scavenging, and protein folding and synthesis, enzymes involved in energy production (carbon metabolism and ATP synthesis) system were upregulated under heat stress. Taken together, these findings improve our understanding of the molecular mechanisms underlying the response of heat stress in H. marmoreus.
Highlights
Hypsizygus marmoreus is one of the most popular industrialized cultivation mushrooms in East Asia, including China, Korea and Japan (Qiu et al, 2013; Chauhan et al, 2017; He et al, 2019; Wu et al, 2019)
This study provides the mechanism of nitric oxide, which could upregulate the expression of heat shock proteins (HSPs) and reactive oxygen species (ROS) detoxification enzymes, in thermotolerance of G. oregonense at the gene expression level
H. marmoreus mycelia were divided into three groups, mycelia grew at 25◦C for 16 days (Con group), mycelia grew at 25◦C for 15 days following a heat treatment at 37◦C for 24 h (HS group), and mycelia grew at 25◦C for 11 days following a 24 h heat treatment and 7 days recovery growth (RHS group) (Figure 1A)
Summary
Hypsizygus marmoreus is one of the most popular industrialized cultivation mushrooms in East Asia, including China, Korea and Japan (Qiu et al, 2013; Chauhan et al, 2017; He et al, 2019; Wu et al, 2019). The mycelia grow vegetatively at 23◦C to 25◦C and transform into fruiting process at 13◦C to 17◦C. The fruiting process of H. marmoreus is sensitive to temperature, and high temperature can lead to the death of mycelia and malformation of the fruiting body (Zhang et al, 2019; Xu et al, 2020). Thermotolerance is important for H. marmoreus during both vegetative growth and fruiting-body formation. Previous studies on H. marmoreus have mainly focused on cultivation, nutrition and bioactive compounds extracted (Mleczek et al, 2018; Saito et al, 2018; Oliveira et al, 2019; Tsai et al, 2019), but little is known about thermotolerance of this mushroom
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