3.3.1. ROS metabolism under LNT
Plants use O2 as a terminal electron acceptor in both photorespiration and Mehler reaction to protect the chloroplasts from
photodamage under environmental stress conditions [9]. Asada [49] proposed that the water–water cycle is an effective mechanism under stress. However, the production of active oxygen species may be related to increased electrons that are transported to the Mehler reaction and accompanied by the inhibition of the Calvin cycle and photorespiration during chilling stress [9]. Using a previously described method [25], we estimated the electron flux in PSII and found that LNT-induced decreases in Je (PCR) was mostly compensated by Ja (O2-dependent; Table 4). The higher proportion