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EEMS2015 organizing committee
Published in Yeping Wang, Jianhua Zhao, Advances in Energy, Environment and Materials Science, 2018
Phenylalanine Ammonia Lyase (PAL) is the first enzyme of the general phenylpropanoid metabo- lism and controls a key branch point in the bio- synthetic pathways of flavanoid phytoalexins which are mostly antimicrobial compounds (Bow- les, 1990). Reactive Oxigen Species (ROS) burst is a typical characteristic of cells under stress. And MDA is the oxidant product of membrane lipid under stress conditions. Plants evolve elaborate mechanism to maintain the balance of produc- tion of scavange of ROS, Polyphenol Oxidase (PPO), Peroxidase (POD) and Catalase (CAT) are three key enzymes involving in ROS scavenge. To unveil the underline mechanism of MeJA induced common scab resistance of potato, we detected the content of superoxide anion free radical and MDA, and the activity of PAL, PPO and CAT.
Explicating the effect of the ozonation on quality parameters of onion (Allium cepa L.) in terms of pungency, phenolics, antioxidant activity, colour, and microstructure
Published in Ozone: Science & Engineering, 2023
Pramod S. Shelake, Debabandya Mohapatra, Manoj Kumar Tripathi, Saroj Kumar Giri
Phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) is known for initiating the phenylpropanoid biosynthesis pathway and is generally found in most of the higher plants. It helps in breaking down of ammonia group from L-phenylalanine, resulting in the formation of trans-cinnamate, initiating the biosynthesis of plant-specific phenylpropanoid derivatives, such as phenolics (Benkeblia 2000). Ozone treatment to onion could be attributed to the activation of PAL (Ali, Ong, and Forney 2014), which resulted in increased phenolic and flavonoids content. Another reason for the increase in phenol might be the cell wall modification during ozone treatment that caused enhanced extractability and release of some conjugated phenolic compounds. At higher concentrations, however, ozone decomposition produces numerous free radicals that scavenge phenolic compounds in commodity, resulting in a decrease in the phenolic and flavonoid contents (Alothman et al. 2010). This might have resulted in a decrease in phenolics after an effective ozone concentration of 400 ppm.
Compost and mycorrhizae application as a technique to alleviate Cd and Zn stress in Medicago sativa
Published in International Journal of Phytoremediation, 2021
Anas Raklami, Abdelhay El Gharmali, Youssef Ait Rahou, Khalid Oufdou, Abdelilah Meddich
The cultivation of alfalfa under heavy metals stresses induced the accumulation of polyphenolic compounds. Phenolic compounds play beneficial roles in protecting excess Zn and Cd (Mongkhonsin et al.2016). Polyphenoloxidase activity is involved in the oxidation of phenolic compounds into quinones that participate in the linkage of the different constituents of the wall and consequently increase its rigidity (Avdiushko et al.1993). Activation of phenylalanine ammonia-lyase (PAL) is a key enzyme in the biosynthesis pathway of phenylpropanoids responsible for phenol synthesis in plants (Zhang and Liu 2015). Many antioxidants including secondary metabolites, especially phenols, play a key role in adapting plants to abiotic stress (Hernández et al.2004; Liu et al.2006). These phenolic compounds could also act as metal chelators or could directly attenuate oxidative damage by removing free radicals (Vollmannova et al.2014). Under heavy metal stress, salicylic acid interacts with other plant hormones (e.g., auxins, abscisic acid, gibberellin) and promotes the stimulation of antioxidant compounds and enzymes thereby improving plant tolerance to metallic stress (Song et al.2014; Sharma et al.2020).