Figure 7.

Schematic of cold acclimation (CA) in this study. The proposed model suggests that the demand for photoprotection in overwintering leaves during CA under field conditions could be the reason for decreased abscisic acid (ABA) and jasmonic acid (JA) contents and thus the decrease in lignin content. The upregulation of circadian rhythm-related genes could play key roles in increasing freezing tolerance. NPQ, photochemical quenching; ROS, reactive oxygen species. The dashed lines indicate that the inferences need further investigation.