Enhancement of Antioxidant Systems and Storability of Two Plum Cultivars by Preharvest Treatments with Salicylates.

Alejandra Martínez-Esplá,Domingo Martínez-Romero,Pedro Zapata,María Serrano,Daniel Valero,Salvador Castillo

doi:10.3390/ijms18091911

Alejandra Martínez-Esplá, Domingo Martínez-Romero + Show 4 more

Open Access

https://doi.org/10.3390/ijms18091911

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Abstract

In this research the effect of salicylic acid (SA), acetylsalicylic acid (ASA), and methylsalicylate (MeSA) treatments, applied as a foliar spray during on-tree plum development, on fruit quality attributes, bioactive compounds, antioxidant activity, and the activity of the antioxidant enzymes at harvest and after long-term cold storage was evaluated in two plum cultivars (“Black Splendor”, BS, and “Royal Rosa”, RR). At harvest, plum quality parameters, such as weight, total phenolics (including anthocyanins, in BS), total carotenoids, and antioxidant activity, in both hydrophilic and lipophilic compounds were found at higher levels in plums from SA-, ASA-, and MeSA-treated trees than in those from control trees. During storage, fruit firmness, total acidity, and antioxidant compounds were at higher levels in treated, than in control, plums, which show an effect of salicylate treatments on delaying the plum postharvest ripening process. In addition, the activity of the antioxidant enzymes catalase (CAT), peroxidase (POX), superoxide dismutase (SOD), and ascorbate peroxidase (APX) were also enhanced at the time of harvest in salicylate-treated plums as compared with plums from control trees. The activity of these antioxidant enzymes was also found at higher levels in salicylate-treated plums during storage. Thus, preharvest treatment with salicylates could be a safe, eco-friendly, and new tool to improve and maintain plum quality attributes, and especially their content of antioxidant compounds, with an additional effect on delaying the postharvest ripening process through increasing the levels of antioxidant compounds and the activity of the antioxidant enzymes.

Highlights

Oxidative stress in plant cells involves the accumulation of free radicals, especially reactive oxygen species (ROS), such as the superoxide radical (O2−), hydrogen peroxide (H2O2), and hydroxyl radical (OH−) [1]
Since the overall process of fruit ripening is considered as a functionally-modified protracted form of senescence, associated with ROS accumulation [2], the presence of a high content of antioxidant compounds and high activity of antioxidant enzymes could lead to a delay of the fruit postharvest ripening process and maintain fruit quality attributes for a long time
During cold storage significant increases in ripening index (RI) were observed in all plum fruits, mainly due to decreases in Total Acidity (TA), these changes were significantly delayed in plums from treated trees

Summary

Introduction

Oxidative stress in plant cells involves the accumulation of free radicals, especially reactive oxygen species (ROS), such as the superoxide radical (O2−), hydrogen peroxide (H2O2), and hydroxyl radical (OH−) [1]. In spite of the presence of these efficient antioxidant systems, oxidative damage still occurs in plant cells either due to uncontrolled production or inefficient scavenging of ROS, which usually occurs under stress conditions and associated to senescence. In this sense, since the overall process of fruit ripening is considered as a functionally-modified protracted form of senescence, associated with ROS accumulation [2], the presence of a high content of antioxidant compounds and high activity of antioxidant enzymes could lead to a delay of the fruit postharvest ripening process and maintain fruit quality attributes for a long time

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