ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Crop and Product Physiology
This article is part of the Research TopicPlant Phenotyping for AgricultureView all 20 articles
ROS-mediated membrane damage and antioxidant imbalance drive apple flesh browning during cold storage
Provisionally accepted
Jihan Wang1Fujun Li1Bingru Li1Ling Li2Jing Shang1Xiaodong Fu1Xiuming Zhao1
Xiaoan Li1
Xinhua Zhang1*
Zienab F R Ahmed3*- 1Shandong University of Technology, Zibo, China
- 2Beijing Vocational College of Agriculture, Beijing, China
- 3United Arab Emirates University, Al Ain, United Arab Emirates
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Apple flesh browning represents a key postharvest problem affecting fruit quality under cold storage, yet its underlying mechanisms remain unclear. In this study, we compared reactive oxygen species (ROS) metabolism among flesh-browning (FB) and normal (FN) tissues of browning apples, as well as healthy apple flesh (Control) from 'Fuji' apples during cold storage (-1~0°C) for 120 days. Results demonstrated a significant increase in enzymatic browning activity in FB and FN tissues, with polyphenol oxidase (PPO) and peroxidase (POD) activities elevated to 2.6-fold and 1.7-fold those of controls, respectively, primarily attributed to compromised membrane compartmentalization. FB tissues exhibited intensified oxidative stress, evidenced by ROS (H2O2 and O2•-) accumulation, increased lipoxygenase (LOX) activity and electrical conductivity (EC), as well as elevated malondialdehyde (MDA) content. Meanwhile, the total antioxidant capacity (TAC) decreased by approximately 25%. Although the phenylpropanoid pathway was up-regulated in FB tissues, the resultant accumulation of phenolics and flavonoids was insufficient to counteract oxidative damage. Importantly, the antioxidant defense systems were impaired: levels of ascorbic acid (AsA) and glutathione (GSH) were significantly reduced, accompanied by decreased catalase (CAT) and ascorbate peroxidase (APX) activities, thereby exacerbating ROS accumulation. Correlation analysis confirmed strong links between browning intensity (as indicated by a* value), ROS levels, and antioxidant deficiency. Collectively, prolonged low-temperature storage induces ROS-mediated membrane damage, triggering enzymatic browning. The simultaneous reduction of non-enzymatic antioxidants (AsA/GSH) together with the decreased activities of antioxidant enzymes (CAT/APX) instigate a vicious cycle of ROS metabolic imbalance.
Keywords: Apple flesh browning1, Cold storage2, ROS metabolism3, Antioxidant imbalance4, Compartmentalization damage5
Received: 04 Oct 2025; Accepted: 14 Nov 2025.
Copyright: © 2025 Wang, Li, Li, Li, Shang, Fu, Zhao, Li, Zhang and Ahmed. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Xinhua Zhang, zxh@sdut.edu.cn
Zienab F R Ahmed, zienab.ahmed@uaeu.ac.ae
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