Photosystem II has been purified from a transplastomic strain of Nicotiana tabacum according to two different protocols. Using the procedure described in Piano et al. (Photosynth Res 106:221-226, 2010) it was possible to isolate highly active PSII composed of monomers and dimers but depleted in their PsbS protein content. A "milder" procedure than the protocol reported by Fey et al. (Biochim Biophys Acta 1777:1501-1509, 2008) led to almost exclusively monomeric PSII complexes which in part still bind the PsbS protein. This finding might support a role for PSII monomers in higher plants.
Light, as an energy source for plant photosynthesis, can not only affect the growth and development of plants, but also affect their leaf color. This study used white (WL), red (RL), and blue light (BL) to treat tea cuttings, aiming to investigate the effect of light quality on the color of tea leaves. The results showed that tea leaves turned yellow under red light, the SPAD and Fv/Fm values were significantly lower than WL and BL.
Cyclic electron transport (CET) is a vital alternative route that protects against photodamage and aids in energy production. This process depends on proton gradient regulation 5 (PGR5) and PGRL1-dependent pathways associated with CET. The exact roles of these proteins in photosystem I photochemistry under prolonged high light conditions are not fully understood.
Photoprotection in plants includes processes collectively known as nonphotochemical quenching (NPQ), which quench excess excitation-energy in photosystem II. NPQ is triggered by acidification of the thylakoid lumen, which leads to PsbS-protein protonation and violaxanthin de-epoxidase activation, resulting in zeaxanthin accumulation. Despite extensive study, questions persist about the mechanisms of NPQ.
For optimum photosynthetic productivity, it is crucial for plants to swiftly transition between light-harvesting and photoprotective states as light conditions change in the field. The PsbS protein plays a pivotal role in this process by switching the light-harvesting antenna, light-harvesting complex II (LHCII), into the photoprotective state, energy-dependent chlorophyll fluorescence quenching (qE), to avoid photoinhibition in high-light environments. However, the molecular mechanism by which PsbS acts upon LHCII has remained unclear.
The Modern Facilities Horticultural Engineering Technology Center, Shenyang Agricultural University, Shenyang 110866, China; The Key Laboratory of Protected Horticulture, Ministry of Education, Shenyang 110866, China. Electronic address:
PsbS protein is essential for the rapid induction of non-photochemical quenching (NPQ) under low night temperatures (LNTs), but its stability is often affected by adverse environmental conditions. However, the regulatory mechanism for the stability of PsbS or chloroplast proteins remains to be fully characterized. We show that LNT decreases NPQ levels and SlPsbS protein abundance in tomato leaves.
