Postharvest application of glycine betaine ameliorates chilling injury in cold-stored banana fruit by enhancing antioxidant system

SCIENTIA HORTICULTURAE Volume 287, 20 September 2021, 110264 https://doi.org/10.1016/j.scienta.2021.110264Get rights and content HIGHLIGHTS * • GB reduced the CI symptoms of banana fruit. *

• GB enhanced the contents of antioxidant substances. * • GB elevated enzyme activities and gene expression of antioxidant enzymes. * • GB increased total antioxidant capacity. ABSTRACT

Chilling injury (CI) represents a physiological disorder caused by improper low temperature management, which affects the postharvest quality and marketing potential of banana fruit. In this

study, postharvest application of glycine betaine (GB) can significantly reduce the CI incidence of banana fruit during cold storage, as observed by lower CI index, electrolyte leakage,

malondialdehyde (MDA) contents, and higher values of lightness, chlorophyll, soluble sugar contents. Moreover, GB not only increased the antioxidant substances such as total phenolics,

glutathione and ascorbic acids (AsA), but also elevated the enzyme activities and gene expression of the antioxidant enzymes including ascorbate peroxidase (APX), catalase (CAT), superoxide

dismutase (SOD) and peroxidase (POD). In addition, GB could obviously enhance the total antioxidant capacity of banana fruit under refrigerated storage. Collectively, these findings suggest

that GB-attenuated CI incidence in banana fruit during cold storage might be, at least partially, ascribed to the enhancement of antioxidant system involving antioxidant substances, as well

as enzyme activities and gene expression of antioxidant enzymes. INTRODUCTION Fresh fruits and vegetables are major sources of phytonutrients, vitamins, carotenoids, phenolics, and dietary

fiber that are beneficial for the human health (Veiga et al., 2020). However, fruits and vegetables are still alive after harvest and become easily perishable, due to the high metabolism.

Refrigerated storage has been applied commonly to maintain the quality and prolong the market life of fruits and vegetables, since low temperatures minimize respiration rate and reduce

pathogen spoilage. Banana being a typical subtropical fruit are sensitive to cold temperature and easy to develop chilling injury (CI) symptoms which involves browning, pitting, inhibition

of starch-sugar conversion, decline in aroma formation and susceptibility to microbial decay (Olorunda et al., 1978). CI can occur at any stage in the supply chain system such as harvesting,

transportation and preservation, and the severity of CI depends on cultivar, developmental stage, temperature, duration of exposure, and postharvest managements (Ba et al., 2016). The

mechanism(s) underlying CI occurrence together with the subsequent development of symptoms are not fully understood, and a better understanding of this mechanism can help apply efficient

strategies to decrease the loss caused by CI. It is well accepted that chilling stress destroys the equilibrium between reactive oxygen species (ROS) generation and scavenging mechanisms

(Hodges et al., 2004). Excessive production of ROS causes oxidative stress, which results in lipid peroxidation, protein degradation, DNA damage, and ultimately cell death (Mittler, 2002).

In general, stress-stimulated ROS production can be removed by enzymatic antioxidant systems that consist of many scavengers like superoxide dismutase (SOD), ascorbate peroxidase (APX),

glutathione peroxidase (GPX), glutathione S-transferase (GST), and catalase (CAT), and non-enzymatic substances with antioxidant activity such as ascorbic acid (AsA), glutathione (GSH),

phenolic compounds, α-tocopherols, carotenoids and flavonoids (Apel and Hirt, 2004). ROS-induced damage is determined by when ROS is accumulated excessively or when the ROS-scavenging system

is not properly working, and induction of the cellular antioxidant machinery is proved to be an essential protection to the tissue against stresses such as chilling. Glycine betaine (GB,

N,N,N-trimethylglycine), a small zwitterionic compound, plays a critical role in environmental adjustment in plants (Sakamoto and Murata, 2002). Exogenous utilization of GB has been reported

to attenuate CI in a variety of horticultural products. For example, GB treatment was able to enhance chilling tolerance in sweet pepper by promoting the enzyme activities and gene

accumulation of antioxidant enzymes (Wang et al., 2016). Similarly, GB application reduced the CI in peach fruit under refrigerated preservation by inducing energy status and production of

GB, GABA, proline compounds and membrane fatty acid metabolism (Shan et al., 2016; Wang et al., 2019a). More recently, GB improves CI symptoms of ‘Nanguo’ pears through modulating

phenylpropanoid, soluble sugar, antioxidant enzymes and proline metabolisms (Sun et al., 2020; Wang et al., 2020). In banana, although preharvest foliar applications of GB could prevent the

CI development of postharvest banana fruit during low temperature storage (Rodríguez-Zapata et al., 2015), it is not known whether postharvest treatment of GB has an effect on improving CI

of banana fruit under refrigerated storage. Therefore, the main purpose of this work was to study the effects of GB on CI and some physiological traits of banana fruit during storage under

chilling conditions. Moreover, its contributions to antioxidant system including some bioactive compounds -like total phenols, AsA, and GSH, as well as antioxidant enzymes involving APX,

CAT, POD and SOD were investigated. Finally, the --total antioxidant capacity were also measured in GB-treated bananas during low temperature storage. SECTION SNIPPETS FRUIT AND HANDLING

Banana fruit (_Musa acuminata_, AAA group cv. ‘Brazil’) at mature-green stage (approximately 100–110 days after anthesis) were picked from the commercial field in Nansha District, Guangzhou,

China, and then they were divided into individual fingers. The fruit with consistent size, maturity, and without any apparent defects were chosen for the following experiment. The fruit

were randomly separated into four groups and subjected to GB treatment by fruit immersing in 0, 50, 100, 150 mM GB solution CI OCCURRENCE IN BANANA FRUIT Peel browning and pitting, the most

obvious symptoms of CI in bananas, were firstly observed in fruit after 3 days of storage at 7 °C, and they were increased with the storage time extending (Supplementary Fig. S1). Compared

with the control, application of 50, 100 and 150 mM GB markedly alleviated the peel browning and pitting in cold-stored bananas (Supplementary Fig. S1), reflecting the protective effect of

GB against CI. The observations of GB effects on CI of bananas can only judged CONCLUSIONS The results obtained in this study indicate that GB treatment can effectively relieve the CI of

banana fruit. The amelioration of CI by GB application may be likely resulted from the maintenance of higher contents of non-enzymatic and enzymatic antioxidants, which could potentially

prevent the accumulation of ROS and thus protect the cells against oxidative damage. DECLARATION OF COMPETING INTEREST The authors declare that they have no conflict of interest.

ACKNOWLEDGEMENTS This research was funded by the -National Natural Science Foundation of China (Grant No. -31830071), Innovation Team Project of Universities in Guangdong Province (Grant No.

2018GKCXTD005), Guangdong Special Support Program (Grant No. 2017TQ04N512) and China Agriculture Research System (Grant No. CARS-31–11). REFERENCES (39) * M.S. Aghdam_ et al._ EXOGENOUS

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RELATED GENES IN BANANA FRUIT IN RESPONSE TO CHILLING TOLERANCE POSTHARVEST BIOL. TECHNOL. (2014) View more references CITED BY (70) * GLYCINE BETAINE INHIBITS POSTHARVEST SOFTENING AND

QUALITY DECLINE OF WINTER JUJUBE FRUIT BY REGULATING ENERGY AND ANTIOXIDANT METABOLISM 2023, Food Chemistry Show abstract Winter jujube fruit easily softens after harvest. To investigate the

effects of glycine betaine (N,N,N-trimethylglycine; GB) treatment on the quality of postharvest jujubes, fresh winter jujubes (_Zizyphus jujuba_ Mill. cv. Dongzao) were immersed in 20 

mmol·L−1 GB for 20 min. The results showed that GB application can effectively maintain cell wall component content by restraining gene expression and enzyme activities, including PG, CX,

PME and β-Glu. Meanwhile, the activities of antioxidant enzymes (APX, CAT, SOD, POD) and the contents of nonenzymatic antioxidants (MDA, H2O2, ASA, GSH) were enhanced in treated jujubes,

thereby reducing the content of ROS. In addition, energy metabolism enzyme activities (H+-ATPase, Ca2+-ATPase, SDH and CCO) and gene expression were also significantly increased, thus

maintaining higher energy levels (ATP, ADP, AMP and EC). In summary, GB enhances ATP biosynthesis by increasing energy metabolism. It offers essential energy for the antioxidant metabolism,

thus retarding the softening of postharvest jujubes. * POSTHARVEST Γ-AMINOBUTYRIC ACID APPLICATION MITIGATES CHILLING INJURY OF AONLA (EMBLICA OFFICINALIS GAERTN.) FRUIT DURING LOW

TEMPERATURE STORAGE 2022, Postharvest Biology and Technology Show abstract Aonla is a nutrients rich underutilized subtropical fruit. It has short shelf life and is prone to chilling injury

(CI) below 6 °C. So, the effect of γ-aminobutyric acid [5 mmol L−1 (GABA)] was investigated on aonla fruit CI mitigation during low temperature storage at 5 ± 1 °C for 24 d. Results showed

that GABA treatment markedly suppressed CI, decay incidence, membrane permeability, malondialdehyde, superoxide anion and hydrogen peroxide in contrast with control. Treated fruit showed

higher activity of glutamate decarboxylase (GAD) and GABA transaminase (GABA-T) enzymes which ultimately resulted in increased endogenous GABA content accumulation. Similarly, GABA

application stimulated the activities of Δ1-pyrroline-5-carboxylate synthetase (P5CS) and ornithine aminotransferase (OAT) enzymes which thus enhanced proline accumulation. The GABA treated

fruit exhibited higher phenylalanine ammonia lyase (PAL) and reduced polyphenol oxidase (PPO) enzyme activity and showed higher total phenols accumulation. In addition, total flavonoids,

ascorbic acid and glutathione content were also significantly higher in GABA treated aonla fruit. In addition, GABA treated aonla fruit exhibited markedly higher ascorbate peroxidase (APX)

catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) activities in comparison with the control. In addition, GABA treated fruit showed lower total soluble solids, ripening index

and juice pH along with markedly higher concentration of titratable acidity. In conclusion, GABA treatment could be used for CI mitigation and overall quality maintenance of cold stored

aonla fruit. * CARBOXYMETHYL CELLULOSE-BASED WATER BARRIER COATING REGULATED POSTHARVEST QUALITY AND ROS METABOLISM OF PAKCHOI (BRASSICA CHINENSIS L.) 2022, Postharvest Biology and

Technology Show abstract The postharvest preservation of _Brassica_ vegetables has received much attention for improving their nutritional and commercial value. In this study, carboxymethyl

cellulose (CMC)-based cross-linking coating embedded with liquid paraffin was prepared to preserve fresh pakchoi (_Brassica chinensis_ L.) and its effects on postharvest water loss, quality

and reactive oxygen species (ROS) metabolism were evaluated. Results showed that ionic cross-linking and liquid paraffin reinforced the structure compactness and water barrier property of

CMC coating by uniformly distributing liquid paraffin in cross-linking network. The novel CMC-based coating effectively reduced water loss and improved appearance and nutrition of fresh

pakchoi stored at 25 °C and 60 % relative humidity for 48 h. Furthermore, the coating treatment enhanced ROS scavenging capacity and reduced lipid peroxidation, which was attributed to the

improvement of antioxidant enzyme activities, ascorbate-glutathione cycle and phenylpropanoid metabolism. This work demonstrates that the novel CMC-based water barrier coating is promising

to control the water loss of pakchoi and further maintain the whole quality by regulating ROS metabolism. * ETHYLENE ATTENUATES CHILLING INJURY OF BANANA FRUIT VIA THE MABHLH060/183 MODULE

IN CONTROLLING PHOSPHATIDIC ACID FORMATION GENES 2022, Postharvest Biology and Technology Citation Excerpt : Banana fruit undergo CI development during improper low temperature storage for a

certain time, which results in poor fruit quality and severe economic loss (Chen et al., 2008). More recently, application of glycine betaine and melatonin was able to ameliorate the CI of

bananas at least partially by enhancing the antioxidant system to minimize the ROS toxicity caused by chilling stress (Chen et al., 2021a,b; Wang et al., 2021). Besides the chemical

treatments, postharvest practices such as heat treatment (Chen et al., 2008), UV-illumination (Pongprasert et al., 2011), ultrasound treatment (Khademi et al., 2019) were also found to

attenuate the CI of bananas. Show abstract Chilling injury (CI) of banana represents a serious problem constraining postharvest preservation in the industry. Application of ethylene was

found to efficiently attenuate CI of banana, however, the mechanism of which remains to be investigated. Here, we found that application of ethrel could ameliorate the CI of banana, as

evidenced by lower CI index, electrolytic leakage and malondialdehyde content. Meanwhile, expression of phosphatidic acid (PA) formation genes _MaPLDδ1_, _MaPLDδ5_ and _MaDGK2_, as well as

two transcriptional regulators _MabHLH060_ and _MabHLH183_ was significantly increased with the progression of CI, but decreased under ethrel treatment. MabHLH060 and MabHLH183 were shown to

locate in nucleus and have transactivation ability. Importantly, these two transcriptional regulators MabHLH060/183 recognized the E-box elements in the promoters of _MaPLDδ1_, _MaPLDδ5_

and _MaDGK2_, and promoted their transcription. Together, these findings suggest that ethylene-alleviated CI of banana may involve the MabHLH060/183 module in modulating the expression of PA

formation genes. * CEO<INF>2</INF> NANOPARTICLES MODULATE CU-ZN SUPEROXIDE DISMUTASE AND LIPOXYGENASE-IV ISOZYME ACTIVITIES TO ALLEVIATE MEMBRANE OXIDATIVE DAMAGE TO IMPROVE

RAPESEED SALT TOLERANCE† 2022, Environmental Science: Nano * MECHANISMS OF CHITOSAN NANOPARTICLES IN THE REGULATION OF COLD STRESS RESISTANCE IN BANANA PLANTS 2021, Nanomaterials View all

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