Economic photoprotection in photosystem II that retains a complete light-harvesting system with slow energy traps

Abstract

The light-harvesting antenna of higher plant photosystem II has an intrinsic capability for self-defence against intense sunlight. The thermal dissipation of excess energy can be measured as the non-photochemical quenching of chlorophyll fluorescence. It has recently been proposed that the transition between the light-harvesting and self-defensive modes is associated with a reorganization of light-harvesting complexes. Here we show that despite structural changes, the photosystem II cross-section does not decrease. Our study reveals that the efficiency of energy trapping by the non-photochemical quencher(s) is lower than the efficiency of energy capture by the reaction centres. Consequently, the photoprotective mechanism works effectively for closed rather than open centres. This type of defence preserves the exceptional efficiency of electron transport in a broad range of light intensities, simultaneously ensuring high photosynthetic productivity and, under hazardous light conditions, sufficient photoprotection for both the reaction centre and the light-harvesting pigments of the antenna.

Nonphotochemical Chlorophyll Fluorescence Quenching: Mechanism and Effectiveness in Protecting Plants from Photodamage

“…Although there is no denial that the LHCII antenna undergoes reorganization into the NPQ state, recent data suggest that it does not uncouple energetically from RCII (Johnson and Ruban, 2009;Belgio et al, 2014), as was previously proposed (Holzwarth et al, 2009), which is in total agreement with the earlier established and experimentally confirmed relationship between the yield of PSII and NPQ (Genty et al, 1989). Moreover, it was shown that NPQ protects closed, not open, RCII, which makes this protective strategy economical, as it does not allow much competition between NPQ and RCII traps for energy under low or moderate light intensity .…”

Photoprotective capacity of non-photochemical quenching in plants acclimated to different light intensities

“…Whole leaves were removed from plants after 45 min dark adaptation and then subjected to three saturating pulses (1000 lmol m -2 s -1 , 0.6 s width). Vacuum infiltration was then performed on leaves with 10 mM Hepes pH 7.5, 150 mM sorbitol and 30 lM DCMU (for more details, see Belgio et al 2012Belgio et al , 2014. 20 s after infiltration, a pre-programmed fast trigrun (Walz, Germany) of 7 lmol m -2 s -1 measuring light intensity was performed.…”

“…These values were taken from a number of previous reports (Pessarakli 2005;Dall'Osto et al 2006;Caffarri et al 2009;Amunts et al 2010). For more details see Table 1 from Belgio et al (2014). Chlorophyll a/b ratios of each photosystem component were taken from Table 2 in Hogewoning et al (2012).…”

Night Light-Adaptation Strategies for Photosynthetic Apparatus in Yellow-Poplar (Liriodendron tulipifera L.) Exposed to Artificial Night Lighting

“…The PSII as the heart of the photosynthetic process is highly sensitive to the environmental stresses. Its activity could be determined with one non-invasive time-resolved fluorescence measurement, which could measure the polyphasic rise with the basic steps of OJIP [43,[48][49][50][51][52][53][54]. Several studies have shown that the chlorophyll a transient has become one of the most popular tools to estimate stress-induced changes in photosynthetic performance.…”