Calcium chloride treatment delays the quality deterioration of king oyster mushroom (Pleurotus eryngii) through positive regulation of antioxidants by PeCaMK1

Abstract

Calcium (Ca2+) signaling plays a crucial role in the growth, development, and stress responses of mushrooms. However, its specific mechanisms in regulating postharvest quality are not fully understood. This study aimed to investigate the underlying mechanism of CaCl2 treatment on the quality of postharvest Pleurotus eryngii and provide theoretical support for the development of future preservation technology. The study found calcium chloride (CaCl2) treatment to be effective in delaying the browning of P. eryngii, reducing weight loss, and mitigating cell membrane damage. The antioxidant levels, and Ca2+ fluorescence signal was measured, to further examine the physiological effects of CaCl2 treatment. The study found that CaCl2 treatment stimulated the activities of catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and peroxidase (POD), ultimately reducing reactive oxygen species (ROS) accumulation. CaCl2 also increased cytolytic Ca2+ levels and the expression levels of Ca2+ signaling genes. The overexpression and silencing transformants were constructed to further analyze the role of PeCaMK1, a gene encoding calcium/calmodulin-dependent protein kinase in Ca2+ signaling. The overexpression of PeCaMK1 increased Ca2+ levels, stimulated the activities of antioxidant enzymes, and inhibited ROS accumulation. The reduced expression of PeCaMK1 by RNAi-mediated gene silencing increased ROS level, demonstrating that PeCaMK1 positively regulated the antioxidant effect in response to Ca2+ signaling. In summary, the results suggested that exogenous CaCl2 treatment transmitted Ca2+ signaling through PeCaMK1 to enhance antioxidant activity, reduce ROS accumulation, and ultimately delay the quality deterioration of P. eryngii.