Antioxidative response in variegated Pelargonium zonale leaves and generation of extracellular H2O2 in (peri)vascular tissue induced by sunlight and paraquat

An evaluation of the phytochemical composition, antioxidant and cytotoxicity of the leaves of Litsea elliptica Blume – An ethnomedicinal plant from Brunei Darussalam

“…The high antioxidant capacity of the young L. elliptica leaves may be due to their increased oxidative stress as a result of their higher exposure to light. As oxidative stress increases, flavonoids and antioxidant enzymes may accumulate to combat the detrimental effects of light-induced reactive oxygen species (ROS) ( Agati and Tattini, 2010 , Vidović et al, 2016 ). Additionally, high oxidative stress may also increase carotenoid and superoxide dismutase concentrations in the young leaves of L. elliptica , both of which possess high radical scavenging potentials and can catalyse the degradation of superoxide radicals respectively ( Stahl and Sies, 2003 , Merhan, 2017 , Ariz et al, 2010 , Younus, 2018 ).…”

Contrasting Metabolisms in Green and White Leaf Sectors of Variegated Pelargonium zonale—An Integrative Transcriptomic and Metabolomic Study

“…In our previous studies [ 1 , 20 , 21 ], we demonstrated an efficient antioxidant network in P. zonale WL, especially with respect to H 2 O 2 scavenging. Although a whole battery of genes encoding Fe superoxide dismutase (FeSOD), Cu/ZnSOD, the ascorbate–glutathione (Asc-GSH) cycle constituents, and class III peroxidases (PODs) was detected in P. zonale leaves, only several were identified as statistically significant DEGs ( Supplementary Tables S2 and S5 ).…”

“…The variegated pelargonium has served as a model system for a dozen fundamental studies on chloroplast development, chloroplastic DNA inheritance, chlorophyll biosynthesis, and the influence of sink tissue on the photosynthetic machinery and associated redox regulation and ROS turn-over [ 2 , 3 , 4 , 5 , 6 , 20 , 21 , 25 ]. Moreover, it is an excellent model system to study sink-source interactions in terms of carbon and nitrogen reallocation [ 1 , 26 , 27 ].…”

“…Given the absence of photosynthetic ETC and peroxisomes in WL, the subcellular localisation of the enzymatic components of the cellular H 2 O 2 regulatory network is crucial for characterising the antioxidant system in WL. This is particularly important since antioxidants in WL can respond rapidly to accelerated superoxide and H 2 O 2 production in GL [ 21 ]. Moreover, under accelerated Mehler reaction, NADPH oxidase-dependent H 2 O 2 accumulation was observed exclusively in the apoplast of GL bundle sheet cells, but not in WL.…”

“…Natural variegation of P. zonale leaves proved to be an excellent model for comparing photosynthetically active and photosynthetically non-active tissues in terms of H 2 O 2 production within the same leaf providing the same microenvironmental conditions [ 20 , 21 ]. In green leaves, reactive oxygen species (ROS) are mainly produced by photorespiration and the photosynthetic electron transport chain (ETC), even under physiological growth conditions [ 22 ].…”