Fig. 8From: Deep sequencing-based characterization of transcriptome of trifoliate orange (Poncirus trifoliata (L.) Raf.) in response to cold stressQuantification of free polyamines (PAs) of Poncirus trifoliata under cold treatment. Three types of free polyamines, including putrescine, spermine, and spermidine, are assessed by HPLC. The bars represent SE (n = 3). Asterisks show that the values are significantly when compared with the levels at the onset of cold treatment (**P < 0.01)Back to article page