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The plant: nutrition, growth, and response to the environment
Published in Stephen R. Gliessman, V. Ernesto Méndez, Victor M. Izzo, Eric W. Engles, Andrew Gerlicz, Agroecology, 2023
Stephen R. Gliessman, V. Ernesto Méndez, Victor M. Izzo, Eric W. Engles, Andrew Gerlicz
Some kinds of plants have evolved different ways of fixing carbon that reduce photorespiration. Their alternate forms of carbon fixation constitute distinct photosynthetic pathways. Altogether, three types of photosynthesis are known to exist. Each has advantages under certain conditions and disadvantages in others.
Microalgae II: Cell Structure, Nutrition and Metabolism
Published in Arun Kumar, Jay Shankar Singh, Microalgae in Waste Water Remediation, 2021
Photorespiration is a similar process like respiration in other organisms, in which fixed organic carbon is consumed for their growth and CO2 is generated as a byproduct in place of O2 in photosynthesis. This process starts with the reaction of O2 with ribulosebisphosphate to form phosphoglycolate by the help of the enzyme RuBisCo (which functions as an oxygenase). Then phosphoglycolate phosphorylates in to glycolate, which is later transported in to peroxisome to convert to intermediate compound glyoxylate to glycine; and again conveyed to mitochondrion to carry out the final conversion in serine, ammonia and CO2. In this process, no metabolic gain is achieved. The photorespiration process primarily depends on the relative ratio of O2 and CO2 concentrations; it has been observed that a high O2/CO2 ratio (i.e., high concentration of O2 and low concentration of CO2) encourages this process, while a low O2/CO2 ratio prefers carboxylation. Due to low half saturation value i.e., km (which is roughly equal to the level of CO2 in air), RuBisCo shows low affinity to CO2, which leads to shifting of the reaction equilibrium to photorespiration, on facing high irradiance, high oxygen level and reduced CO2 conditions.
Turfgrass Physiology and Environmental Stresses
Published in L.B. (Bert) McCarty, Golf Turf Management, 2018
The enzyme responsible for CO2 fixation in the Calvin cycle is RuBisCO, which can react with O2 as well as with CO2. High O2 levels favor the oxygenase activity whereas high CO2 levels favor the carboxylase activity. The oxygenase activity converts RuBP to 2-phosphoglycolate and 3-phosphoglycerate (3-PGA), rather than the two molecules of 3-PGA produced during carboxylase activity (the normal carboxylase activity of RuBP carboxylase/oxygenase). This oxygenase activity is termed photorespiration (Figure 2.22). It is not true respiration as in glycolysis or the Krebs cycle where carbon compounds are converted to CO2, ATP, and carbon compounds with consumption of O2. Therefore, photorespiration in C3 plants is thought wasteful and reduces photosynthetic efficiency and plant productivity. Although photosynthetically inefficient, photorespiration maintains the flow of energy (NADPH and ATP) from the light reactions to the dark reactions to prevent damage to the photosynthetic apparatus of the light reactions in high-light environments and is necessary for nitrate assimilation. In C4 plants, PEP carboxylase is not affected by O2 as RuBisCO is in C3 plants; thus, in C4 plants, photorespiration is not significant.
A review on the applications of machine learning and deep learning in agriculture section for the production of crop biomass raw materials
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Wei Peng, Omid Karimi Sadaghiani
Conclusively, ML and DL are used to improve the quantity and quality of crop biomass via genetic-scale modifications, such as: engineering in Carbon Metabolism as a metabolic engineering, engineering in carbon concentrating mechanisms, optimizing the properties of key enzymes in the drowing of trees (i.e., Rubisco in the Calvin cycle of C3 plants), estimating enzyme function of plants, rational protein engineering, transferring the C4 Pathway into C3 trees, understanding and identifying genetic markers, improving the nexus between carbohydrate export and source-sink in plants, phenotyping in plants, augmentation of the amount of light absorbed by tree canopies, diminishing energy losses using photo-protection, improving plants breeding methods, photorespiration in plants, and improvement of metabolic pathways.
Understanding foliar accumulation of atmospheric Hg in terrestrial vegetation: Progress and challenges
Published in Critical Reviews in Environmental Science and Technology, 2022
Yanwei Liu, Guangliang Liu, Zhangwei Wang, Yingying Guo, Yongguang Yin, Xiaoshan Zhang, Yong Cai, Guibin Jiang
Plant leaves continue to accumulate Hg(0) when the catalase activity was inhibited (Du & Fang, 1983), suggesting that other Hg(0) oxidation routes exist. Several possible mechanisms of foliar Hg(0) oxidation are proposed in this review (Fig. 2). In addition to H2O2, other reactive oxygen species (ROS), such as HO•, O2•-, and 1O2, are also generated during leaf photosynthesis, respiration, and photorespiration. It is possible that foliar Hg(0) oxidation may be linked with the generation and scavenging of various ROS species in foliage. Solar radiation also affects Hg oxidation reactions, with in vitro conversion ratios of 203Hg(0) by leaf homogenates estimated as 2.4 − 12.3% during light exposure, compared with 1.9 − 8.6% in the dark (Du & Fang, 1983). Acceleration of foliar Hg(0) oxidation by solar radiation may be related to direct photooxidation, or ROS generated during leaf photosynthesis and photorespiration.
Laccase immobilization with metal-organic frameworks: Current status, remaining challenges and future perspectives
Published in Critical Reviews in Environmental Science and Technology, 2022
Wenguang Huang, Wentao Zhang, Yonghai Gan, Jianghua Yang, Shujuan Zhang
Electron transfer is a vital process for encouraging redox enzymatic reactions in a definite space (Kraut et al., 2003). To accelerate the electron transfer in laccase, articles focusing on light irradiation as auxiliary strategy have been published in recent years (Jalila Simaan et al., 2011; Kim & Park, 2019; Lam et al., 2016; Lazarides et al., 2013; Lee et al., 2018; Li et al., 2015; Schneider et al., 2015; Robert et al., 2017; Skorupska et al., 2012). By mimicking the enzymatic and photochemical processes in nature, for example photosynthesis and photorespiration in chloroplast, clean solar energy can be used to drive the catalytic reaction and ultimately converted into chemical energy. Herein we review recent advance in the photo-activation of laccase using light-driven electron transfer as a united approach combining photocatalysis and biocatalysis. Furthermore, to handle the existing problems during the process of photo-activation, it is proposed that MOFs can be used as both photocatalyst and enzyme-carrier to improve the activity of immobilized laccase.