Effects of low temperature and cold-acclimation on photoinhibition and singlet oxygen production in four natural accessions ofArabidopsis

Abstract

 Low temperature decreases PSII damage in vivo, in agreement with earlier in vitro results. Susceptibility to photoinhibition differs among Arabidopsis accessions and moderately decreases after cold-acclimation. Flavonols may alleviate photoinhibition. AbstractTo understand the effects of low temperature and cold-acclimation on reactive oxygen species and photoinhibition of photosystem II (PSII), light-induced inactivation of PSII was measured at 22 and 4 °C from four Arabidopsis thaliana accessions (Rschew, Tenela, Columbia-0 and Coimbra) grown under optimal conditions. Photoinhibition was also measured at 4 °C from plants cold-acclimated at 4 °C for two weeks. Measurements were done in the absence and presence of lincomycin that blocks PSII repair, and PSII activity was assayed with the ratio of variable to maximum chlorophyll a fluorescence (FV/FM) and with light-saturated rate of oxygen evolution using a quinone acceptor. Of the nonacclimated accessions, Rschew was the most tolerant to photoinhibition and Coimbra the least; the rate constants of photoinhibition of the most sensitive accession were 1.3-1.9 times as high as those of the tolerant ones. The damaging reaction of photoinhibition in non-acclimated plants was slower or equal at 4 °C than at 22 °C. The rate constants of photoinhibition of cold-acclimated plants, at 4 °C, were 0.55 to 1.25 times as high as those of non-acclimated plants; the protective effect of coldacclimation on photoinhibition was consistent in Columbia-0 and Coimbra whereas Rschew and Tenela were either slightly more tolerant or susceptible, depending on the method used to assay photoinhibition. Production of singlet oxygen, measured from thylakoid membranes isolated from non-acclimated and cold-acclimated plants, did not decrease due to cold-acclimation, nor did singlet oxygen production correlate with the rate of photoinhibition or with flavonol contents of the leaves.

Singlet Oxygen in Plants: Generation, Detection, and Signaling Roles

“…The redox potential of the plastoquinone Q A in PS II can vary ( Figure 3); for instance, it increases upon 3-(3 , 4 -dichlorophenyl)-1, 1-dimethylurea (DCMU) binding to PS II [10]. A positive shift of the Q A potential also occurs under cold stress [19][20][21][22] and in high light when a strong acidification of the thylakoid lumen leads to Ca 2+ release from the oxygen-evolving complex (OEC) of PS II [15,23]. These data were obtained not only with isolated thylakoid membranes but also in vivo.…”

Tanned or Sunburned: How Excessive Light Triggers Plant Cell Death

“…Even when leaf temperature is controlled by lowering air temperature, different setups have been adopted, such as 600 mol photons m -2 s -1 PFD at 23°C air temperature (Balfagón et al, 2019), 1500 mol photons m -2 s -1 at 7°C (Ramel et al, 2012;D'Alessandro et al, 2018), 1200 mol photons m -2 s -1 at 18°C (Lv et al, 2015), 1200 mol photons m -2 s -1 at 11.5°C (Huang et al, 2019) or 2000 mol photons m -2 s -1 at 4°C (Mattila et al, 2019). These studies show that leaf temperature remains at standard levels (20-22°C) when exposed to 1500 mol photons m -2 s -1 at 7°C or 1200 mol photons m -2 s -1 at 11.5°C.…”