Current Knowledge on Mechanisms Preventing Photosynthesis Redox Imbalance in Plants

Abstract

Photosynthesis includes a set of redox reactions that are the source of reducing power and energy for the assimilation of inorganic carbon, nitrogen and sulphur, thus generating organic compounds, and oxygen, which supports life on Earth. As sessile organisms, plants have to face continuous changes in environmental conditions and need to adjust the photosynthetic electron transport to prevent the accumulation of damaging oxygen by-products. The balance between photosynthetic cyclic and linear electron flows allows for the maintenance of a proper NADPH/ATP ratio that is adapted to the plant’s needs. In addition, different mechanisms to dissipate excess energy operate in plants to protect and optimise photosynthesis under adverse conditions. Recent reports show an important role of redox-based dithiol–disulphide interchanges, mediated both by classical and atypical chloroplast thioredoxins (TRXs), in the control of these photoprotective mechanisms. Moreover, membrane-anchored TRX-like proteins, such as HCF164, which transfer electrons from stromal TRXs to the thylakoid lumen, play a key role in the regulation of lumenal targets depending on the stromal redox poise. Interestingly, not all photoprotective players were reported to be under the control of TRXs. In this review, we discuss recent findings regarding the mechanisms that allow an appropriate electron flux to avoid the detrimental consequences of photosynthesis redox imbalances.

The Reactions of Photosynthetic Capacity and Plant Metabolites of Sedum hybridum L. in Response to Mild and Moderate Abiotic Stresses

“…Plants have various mechanisms for dissipating excess energy to protect and optimize photosynthesis under adverse conditions [ 18 ]. The literature describes various fluorescence-based parameters for quantum outputs of non-photochemical energy conversion to PS II, Y(NPQ) and Y(NO) that complement the quantum yield of the photochemical energy conversion, Y(II) [ 42 ].…”

“…When reactive oxygen species (ROS) production prevails over an antioxidant defense network, photo oxidant stress occurs [ 13 , 16 , 17 ]. Therefore, when faced with changes in environmental conditions, plants first need to regulate photosynthetic electron transport to prevent the accumulation of damaging oxygen by-products [ 18 ]. Meanwhile, the change in photosynthesis is a consequence of the most painful processes, which are affected by environmental stress factors that cause an increase in the level of stress in plants.…”

Reactive Oxygen Species Initiate Defence Responses of Potato Photosystem II to Sap-Sucking Insect Feeding

“…The response mechanism of photosystem II photochemistry to insect herbivory and its ability to induce a compensatory mechanism that increases PSII photochemistry in response to herbivore feeding is fundamental in plant resistance to herbivores [ 4 ]. The light reactions of photosynthesis involve a set of redox reactions that are the source of energy for producing organic compounds [ 59 ]. According to the growth-differentiation hypothesis, plants have to choose between allocating their resources to defence or growth [ 60 ]; greater allocation of resources to defence comes at the expense of tolerance [ 61 ].…”

Mechanisms Regulating Energy Homeostasis in Plant Cells and Their Potential to Inspire Electrical Microgrids Models

“…Photosynthesis in the chloroplasts involves a set of reactions providing the source of usable energy for cells derived from light energy. The energy is then utilized for assimilation of carbon dioxide (CO 2 ), thus generating carbohydrates as energy storage and oxygen, which supports life on Earth [ 4 ]. As sessile organisms, plants are always exposed to continuous changes in environmental conditions.…”

“…Particularly, severe environments result in excess light energy in the chloroplasts, leading to the accumulation of damaging oxygen by-products. Thus, plants possess the ability to flexibly adjust light absorption and photosynthetic activities to prevent such damages [ 4 ]. For example, plant cells can accumulate a red-colored compound called anthocyanin and filter or reflect harmful radiation [ 5 ].…”