Terpinene and β-pinene acting as signaling molecules to improve Cinnamomum camphora thermotolerance

Cinnamomum camphora has great economic value and produces abundant of monoterpenes to improve the thermotolerance. To uncover the thermotolerance mechanisms of main functional monoterpenes for developing anti-high temperature agents, the reactive oxygen species (ROS) metabolism, photosynthetic abilities and gene expression were investigated in the plant leaves fumigated with 2 main monoterpenes (terpinene and β-pinene) under high temperature (38 °C) with fosmidomycin (Fos) inhibiting monoterpene synthesis (Fos+38 °C + terpinene and Fos+38 °C+β-pinene). High temperature (38 °C) increased the ROS and thiobarbituric acid reactive substance (TBARS) content as well as antioxidant enzyme activities, but declined the photosynthetic abilities. These variations were further aggravated under 38 °C with Fos pretreatment (Fos+38 °C), but were gradually recovered with increasing the monoterpene concentration in Fos+38 °C + terpinene and Fos+38 °C+β-pinene treatments. The expression of 73 genes involving in non-enzymatic antioxidant metabolism, photosynthesis and other pathways was changed in Fos+38 °C treatment. Interestingly, the occurrence of 10 μM terpinene and/ or β-pinene showed recovery effects on the expression of these altered genes. Therefore, terpinene and β-pinene were 2 main functional monoterpenes to improve C. camphora thermotolerance by adjusting gene expression.