Adaptation to environmental changes is crucial for plant growth and survival. However, the molecular and biochemical mechanisms of adaptation are still poorly understood and the signaling pathways involved remain elusive. Active oxygen species (AOS) have been proposed as a central component of plant adaptation to both biotic and abiotic stresses. Under such conditions, AOS may play two very different roles: exacerbating damage or signaling the activation of defense responses. Such a dual function was first described in pathogenesis but has also recently been demonstrated during several abiotic stress responses. To allow for these different roles, cellular levels of AOS must be tightly controlled. The numerous AOS sources and a complex system of oxidant scavengers provide the flexibility necessary for these functions. This review discusses the dual action of AOS during plant stress responses.

Dual action of the active oxygen species during plant stress responses.

The manganese and calcium ions of photosynthetic oxygen evolution.

The various types of biosensors such as enzyme-based, tissue-based, immunosensors, DNA biosensors, thermal and piezoelectric biosensors have been deliberated here to highlight their indispensable applications in multitudinous fields. Some of the popular fields implementing the use of biosensors are food industry to keep a check on its quality and safety, to help distinguish between the natural and artificial; in the fermentation industry and in the saccharification process to detect precise glucose concentrations; in metabolic engineering to enable in vivo monitoring of cellular metabolism. Biosensors and their role in medical science including early stage detection of human interleukin-10 causing heart diseases, rapid detection of human papilloma virus, etc. are important aspects. Fluorescent biosensors play a vital role in drug discovery and in cancer. Biosensor applications are prevalent in the plant biology sector to find out the missing links required in metabolic processes. Other applications are involved in defence, clinical sector, and for marine applications.

Biosensors and their applications - A review.

Emerging pollutants in the environment: present and future challenges in biomonitoring, ecological risks and bioremediation

summary The gradual but huge increase in atmospheric O # concentration that followed the evolution of oxygenic photosynthesis is one consequence that marks this event as one of the most significant in the earth’s history. The high redox potential of the O # }water couple makes it an extremely powerful electron sink that enables energy to be transduced in respiration. In addition to the tetravalent interconversion of O # and water, there exist a plethora of reactions that involve the partial reduction of O # or photodynamic energy transfer to produce active oxygen species (AOS). All these redox reactions have become integrated during evolution into the aerobic photosynthetic cell. This review considers photosynthesis as a whole-cell process, in which O # and AOS are involved in reactions at both photosystems, enzyme regulation in the chloroplast stroma, photorespiration, and mitochondrial electron transport in the light. In addition, oxidants and antioxidants are discussed as metabolic indicators of redox status, acting as sensors and signal molecules leading to acclimatory responses. Our aim throughout is to assess the insights gained from the application of mutagenesis and transformation techniques to studies of the role of O # and related redox components in the integrated regulation of photosynthesis.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1469-8137.2000.00667.x

Tansley Review No. 112

A biosensor for the detection of triazine- and phenylurea-type herbicides was constructed using iso- lated Photosystem II (PS II) complexes as a biosensing element. PSII isolated from the thermophilic cyanobac- terium Synechococcus elongatus was immobilized on the surface of a screen-printed sensor composed of a graphite working electrode and Ag/AgCl reference elec- trode deposited on a polymeric substrate. The biosensor was mounted in a flow microcell with illumination. The principle of the detection was based on the fact that herbicides selectively block PSII electron transport ac- tivity in a concentration-dependent manner. Changes of the activity were registered amperometrically as the rate of photoreduction of an artificial electron acceptor. The setup resulted in a reusable herbicide biosensor with a good stability (half-life of 24 h) and limit of detection of approximately 10 � 9 M for diuron, atrazine and simazine.

/pdf/a-biosensor-for-the-detection-of-triazine-and-phenylurea-4pnh3yijyd.pdf

A biosensor for the detection of triazine and phenylurea herbicides designed using Photosystem II coupled to a screen‐printed electrode

In the 1990's, evidence has accumulated that various unfavourable environmental conditions substantially affect the turnover of the D, protein of reaction centre II, the psbA gene product. Biochemical, molecular and physiological studies in higher plants indicate that alterations of D 1 protein turnover occur under drought, nutrition deficiency, heat, chemical stress, ozone fumigation as well as UV-B and visible photo-stresses. The behaviour of photosystem II under these various stress conditions indicates that the response of D, protein turnover can be interpreted as a general adaptive response to environmental extremes.

Effects of abiotic stresses on the turnover of the D1 reaction centre II protein

https://www.cell.com/trends/biotechnology/pdf/S0167-7799(05)00075-2.pdf

Photosynthetic proteins for technological applications

Photosystem II-based biosensors for the detection of pollutants.

Biosensors are projected to find many applications due to their high selectivity and sensitivity, rapid reaction, economy and ease of handling in field measurements. Even though biosensors for a wide range of environmental pollutants have been extensively reported in the literature, the decision to develop a suitable biosensing system that can be approved by a regulatory perspective for environmental applications is fraught with technical issues. These issues mainly concern the biological recognition element, the physico-chemical transducer and the interfaces between the biological and the physical components, but also aspects of fluidics, electronics, and software for data processing. This article reviews methods together with a process to move biosensor technology from research laboratories to market, focusing as a case in point on challenges and possible opportunities in the development of photosynthetic-based biosensors for environmental applications.

Maria Teresa Giardi

Papers

A biosensor for the detection of triazine and phenylurea herbicides designed using Photosystem II coupled to a screen‐printed electrode

Effects of abiotic stresses on the turnover of the D1 reaction centre II protein

Photosynthetic proteins for technological applications

Photosystem II-based biosensors for the detection of pollutants.

Biosensors for effective environmental and agrifood protection and commercialization: from research to market