Fig. 5

Effects of different abiotic stresses on the expression of PhTPS1–4 and content of (iso)floridoside. a Relative expression of PhTPS1–4 under high temperature stress. The thalli of P. haitanensis were treated at 35 °C for 30 min and subsequently allowed to recover at 20 °C for 1 and 3 h. Control, P. haitanensis cultured in sterilized seawater at 20 °C; − 1/2, Samples exposed to 35 °C for 30 min; 1 and 3 h for recovery time. Values denoted with different letters indicate significant differences according to Tukey’s multiple comparison tests. b Relative expression of PhTPS1–4 under desiccation. The thalli of P. haitanensis were subjected to desiccation for 0, 1, 2, 3, and 4 h under 20 °C, 100 μmol photons m^− 2 s^− 1, and 75% humidity. c Relative expression of PhTPS1–4 under 500 to 1400 mM salt stress for 1 h under 20 °C. d Effect of salt stress on the production of (iso)floridoside in P. haitanensis. The thalli of P. haitanensis were cultured in medium supplemented with 500 to 1400 mM NaCl for 1 h under 20 °C. The bars in (b, c, and d) represent the mean of three biological replicates and three technical repetitions (n = 3), and the error bars depict one SD. One-way ANOVA, *P < 0.05, **P < 0.01 (relative to the control)