Membrane lipid metabolism influences chilling injury during cold storage of peach fruit

The characteristic VOCs of different parts of Artocarpus heterophyllus fruit based on HS-SPME-GC-MS and PTR-TOF-MS

Insight investigation on both edible pulps and inedible parts involving inflorescence axis and shreds of Artocarpus heterophyllus Lam were carried out, a total of 98 VOCs and 201 masses were identified by the combination of HS-SPME-GC-MS and PTR-TOF-MS. Among them, according to the consistency of OAV and results of VIP > 1, p < 0.05, compounds methyl isovalerate (A2), 3-methylbutyl acetate (A5) and octanoic acid, ethyl ester (A21) were recognized as aroma markers to distinguish the pulps, shreds and inflorescence axis. Meanwhile, the inflorescence axis (IC50: 1.82 mg/mL) and shreds (IC50: 16.74 mg/mL) exhibited more excellent antioxidant potency than pulps (IC50: 17.43 mg/mL) in vitro. These findings validated the feasibility of coupling HS-SPME-GC-MS and PTR-TOF-MS for rapid detection of characteristic VOCs of this plant, and offered new prospect of fragrance utilization and waste management of the edible and inedible parts of A. heterophyllus fruit.

Tert-Butylhydroquinone retards longan fruit deterioration by regulating membrane lipid and energy metabolisms

Longan fruit deteriorates rapidly after harvest, which limits its storability. This study aimed to investigate the effect of tert-butylhydroquinone (TBHQ) on quality maintenance, membrane lipid metabolism, and energy status of longan fruit during 25 °C storage. Compared with control fruit, TBHQ treatment maintained better marketable fruit rate and suppressed activities of phospholipase D (PLD), lipase, and lipoxygenase (LOX), and downregulated expressions of DlPLD, DlLOX, and Dllipase. TBHQ also increased the ratio of unsaturated fatty acids to saturated fatty acids (U/S) and the index of unsaturated fatty acids (IUFA). In addition, higher levels of ATP, ADP, energy charge, NADP+/ NADPH as well as higher activities of H+-ATPase, Ca2+-ATPase and NADK were also observed in TBHQ-treated fruit. These results suggested that TBHQ may maintain postharvest quality of longan fruit by regulating membrane lipid and energy metabolisms.

The synthesis of triacylglycerol by diacylglycerol acyltransferases (CsDGAT1A and CsDGAT2D) is essential for tolerance of cucumber's resistance to low-temperature stress

KEY MESSAGE

CsDGAT1A and CsDGAT2D play a positive regulatory role in cucumber's response to low-temperature stress and positively regulate the synthesis of triacylglycerol (TAG). Triacylglycerol (TAG), a highly abundant and significant organic compound in plants, plays crucial roles in plant growth, development, and stress responses. The final acetylation step of TAG synthesis is catalyzed by diacylglycerol acyltransferases (DGATs). However, the involvement of DGATs in cucumber's low-temperature stress response remains unexplored. This study focused on two DGAT genes, CsDGAT1A and CsDGAT2D, investigating their function in enhancing cucumber's low-temperature stress tolerance. Our results revealed that both proteins were the members of the diacylglycerol acyltransferase family and were predominantly localized in the endoplasmic reticulum. Functional analysis demonstrated that transient silencing of CsDGAT1A and CsDGAT2D significantly compromised cucumber's low-temperature stress tolerance, whereas transient overexpression enhanced it. Furthermore, the TAG content quantification indicated that CsDGAT1A and CsDGAT2D promoted TAG accumulation. In conclusion, this study elucidates the lipid metabolism mechanism in cucumber's low-temperature stress response and offers valuable insights for the cultivation of cold-tolerant cucumber plants.

Construction of a Robust Radiative Cooling Emitter for Efficient Food Storage and Transportation

Nowadays, food safety is still facing great challenges. During storage and transportation, perishable goods have to be kept at a low temperature. However, the current logistics still lack enough preservation ability to maintain a low temperature in the whole. Hence, considering the temperature fluctuation in logistics, in this work, the passive radiative cooling (RC) technology was applied to package to enhance the temperature control capability in food storage and transportation. The RC emitter with selective infrared emission property was fabricated by a facile coating method, and Al2O3 was added to improve the wear resistance. The sunlight reflectance and infrared emittance within atmospheric conditions could reach up to 0.92 and 0.84, respectively. After abrasion, the sunlight reflection only decreased by 0.01, and the infrared emission showed a negligible change, revealing excellent wear resistance. During outdoor measurement, the box assembled by RC emitters (RC box) was proved to achieve temperature drops of ∼9 and ∼4 °C compared with the corrugated box and foam box, respectively. Besides, the fruits stored in the RC box exhibited a lower decay rate. Additionally, after printing with patterns to meet the aesthetic requirements, the RC emitter could also maintain the cooling ability. Given the superior optical properties, wear resistance, and cooling capability, the emitter has great potential for obtaining a better temperature control ability in food storage and transportation.

A comprehensive study from the micro- to the nanometric scale: Evaluation of chilling injury in tomato fruit (Solanum lycopersicum)

Tomato fruit is susceptible to chilling injury (CI) during its postharvest handling at low temperature. The symptoms caused by this physiological disorder have been commonly evaluated by visual inspection at a macro-observation scale on fruit surface; however, the structure at deeper scales is also affected by CI. This work aimed to propose a descriptive model of the CI development in tomato tissue under the micro-scale, micro-nano-scale and nano-scale approaches using fractal analysis. For that, quality and fractal parameters were determined. In this sense, light microscopy, Environmental Scanning Electron Microscopy (ESEM) and Atomic Force Microscopy (AFM) were applied to analyse micro-, micro-nano- and nano-scales, respectively. Results showed that the morphology of tomato tissue at the micro-scale level was properly described by the multifractal behaviour. Also, generalised fractal dimension (Dq=0) and texture fractal dimension (FD) of CI-damaged pericarp and cuticle were higher (1.659, 1.601 and 1.746, respectively) in comparison to non-chilled samples (1.606, 1.578 and 1.644, respectively); however, FD was unsuitable to detect morphological changes at the nano-scale. On the other hand, lacunarity represented an appropriate fractal parameter to detect CI symptoms at the nano-scale due to differences observed between damaged and regular ripe tissue (0.044 and 0.025, respectively). The proposed multi-scale approach could improve the understanding of CI as a complex disorder to the development of novel techniques to avoid this postharvest issue at different observation scales.

Transcriptome profiling of Bergenia purpurascens under cold stress

Bergenia purpurascens is an important medicinal, edible and ornamental plant. It generally grows in high-altitude areas with complex climates. There have been no reports about how B. purpurascens survives under cold stress. Here, the B. purpurascens under low temperature were subjected to transcriptomics analysis to explore the candidate genes and pathways that involved in the cold tolerance of B. purpurascens. Compared with the control treatment, we found 9,600 up-regulated differentially expressed genes (DEGs) and 7,055 down-regulated DEGs. A significant number of DEGs were involved in the Ca2+ signaling pathway, mitogen-activated protein kinase (MAPK) cascade, plant hormone signaling pathway, and lipid metabolism. A total of 400 transcription factors were found to respond to cold stress, most of which belonged to the MYB and AP2/ERF families. Five novel genes were found to be potential candidate genes involved in the cold tolerance of B. purpurascens. The study provide insights into further investigation of the molecular mechanism of how B. purpurascens survives under cold stress.

Biochemical and molecular changes in peach fruit exposed to cold stress conditions

Storage or transportation temperature is very important for preserving the quality of fruit. However, low temperature in sensitive fruit such as peach can induce loss of quality. Fruit exposed to a specific range of temperatures and for a longer period can show chilling injury (CI) symptoms. The susceptibility to CI at low temperature varies among cultivars and genetic backgrounds. Along with agronomic management, appropriate postharvest management can limit quality losses. The importance of correct temperature management during postharvest handling has been widely demonstrated. Nowadays, due to long-distance markets and complex logistics that require multiple actors, the management of storage/transportation conditions is crucial for the quality of products reaching the consumer.Peach fruit exposed to low temperatures activate a suite of physiological, metabolomic, and molecular changes that attempt to counteract the negative effects of chilling stress. In this review an overview of the factors involved, and plant responses is presented and critically discussed. Physiological disorders associated with CI generally only appear after the storage/transportation, hence early detection methods are needed to monitor quality and detect internal changes which will lead to CI development. CI detection tools are assessed: they need to be easy to use, and preferably non-destructive to avoid loss of products.

Integration of multi-omics analyses highlights the secondary metabolism response of tomato fruit to low temperature storage

Inappropriate low temperature storage usually leads to quality deterioration of harvested tomato fruits. In this study, we performed comparative metabolome, transcriptome, and proteome analyses to comprehensively understand the effects of low temperature on metabolic changes in tomato fruit (fresh fruit, C0d; 4 °C 8 days, C8d; 4 °C 7 days and then 25 °C 1 day, C7dS1). Large amounts of secondary metabolites (including flavonoids and phenolic acids) increased after low temperature treatment. The overlap differentially accumulated metabolites in three comparative groups (C0d vs. C8d, C0d vs. C7dS1, C8d vs. C7dS1) were mainly flavonoid metabolites. A total of 1438 differentially expressed genes identified in these three comparative groups were primarily enriched in metabolic pathways and secondary metabolites biosynthesis pathways. Similarly, proteomic analysis showed that the differentially expressed proteins were enriched in the secondary metabolites biosynthesis and phenylpropanoid biosynthesis pathways. There was a strong correlation between changes in flavonoid metabolites and the expression of chalcone synthase (SlCHS), chalcone isomerase-like (SlCHIL), and coumarate 3-hydroxylase (SlC3H), which are involved in the phenylpropanoid and flavonoid biosynthesis. Additionally, seven differentially expressed MYB transcription factors were identified; SlMYB91, SlMYB106, and SlMYB70 strongly correlated with flavonoid biosynthesis structural genes after low temperature treatment. Other genes involved in fruit ripening and quality were also affected by low temperature. The data generated in this study may unravel the transcriptional regulatory network of secondary metabolism associated with low-temperature storage and provide a solid foundation for future studies.

Exogenous BR delayed peach fruit softening by inhibiting pectin degradation enzyme genes

Peach fruit deteriorates and senesces rapidly when stored at room temperature. Brassinosteroids (BRs) play an important role in regulating plant growth and development and maintaining fruit quality. However, little information is available on the effect of BRs on the senescence of harvested peach fruit. In this study, different concentrations of BR were used to treat 'Hongniang' peach fruit, and the results showed that 10 μM BR was the most beneficial concentration to delay the senescence of peach fruits. BR treatment delayed the decrease of fruit firmness, the release of ethylene, the increase in water-soluble pectin (WSP) and ionic-soluble pectin (ISP) content and the decrease in covalently bound pectin (CBP) content, inhibited the activities of pectin degradation enzymes, and inhibited the gene expression of PpPME1/3, PpPG, PpARF2, and PpGAL2/16. In addition, BR treatment also inhibited the expression of PpBES1-5/6. Cis-acting regulatory element analysis of pectin degradation enzyme promoters showed that many of them contained BES1 binding elements. All the above results showed that BR treatment had a positive effect on delaying the senescence of peach fruit and prolonging its storage period.

Review of recent advances in post-harvest techniques for tropical cut flowers and future prospects: Heliconia as a case-study

Aesthetic attributes and easy-to-grow nature of tropical cut flowers (TCFs) have contributedto their potential for increased production. The dearth of information regarding agronomic practices and lack of planting materials are the key hindrances against their fast expansion. Unconventional high-temperature storage requirements and the anatomy of the peduncle contribute topoor vase life performance, while troublesome packaging and transport due to unusual size and structureprimarily cause post-harvest quality deterioration. Nonetheless, the exotic floral structuresconsequently increase market demand, particularly in temperate countries. This boosts studies aimed at overcoming post-harvest hindrances. While a few TCFs (Anthurium, Strelitzia, Alpinia, and a few orchids) are under the spotlight, many others remain behind the veil. Heliconia, an emerging specialty TCF (False Bird-of-Paradise, family Heliconiaceae), is one of them. The structural uniquenessand dazzling hues of Heliconia genotypes facilitate shifting its position from the back to the forefrontof the world floriculture trade. The unsatisfactory state-of-the-art of Heliconia research and the absence of any review exclusively on it are the key impetus for structuring this review. In addition to the aforementioned setbacks, impaired water uptake capacity after harvest, high chilling sensitivity, and the proneness of xylem ducts to microbial occlusion may be counted as a few additional factors that hinder its commercialization. This review demonstrates the state-of-the-art of post-harvest research while also conceptualizing the implementation of advanced biotechnological aid to alleviate the challenges, primarily focusing on Heliconia (the model crop here) along with some relevant literature on its other allied members. Standard harvesting indices, grading, and packaging are also part of the entire post-harvest operational chain, but since these phases are barely considered in Heliconia and the majority of tropical ornamentals except a few, a comprehensive account of these aspects has also been given. The hypothesized cues to nip chilling injury, resorting to different bio-chemical treatments, nano-based technology, and advanced packaging techniques, may help overcome preservation difficulties and propel its transition from niche to the commercial flower market. In a nutshell, readers will gain a comprehensive overview of how optimum post-harvest handling practices can rewardingly characterize this unique group of TCFs as the most remunerative component.

Genome-Wide Identification, Classification, and Expression Analyses of the CsDGAT Gene Family in Cannabis sativa L. and Their Response to Cold Treatment

Hempseed is a nutrient-rich natural resource, and high levels of hempseed oil accumulate within hemp seeds, consisting primarily of different triglycerides. Members of the diacylglycerol acyltransferase (DGAT) enzyme family play critical roles in catalyzing triacylglycerol biosynthesis in plants, often governing the rate-limiting step in this process. As such, this study was designed to characterize the Cannabis sativa DGAT (CsDGAT) gene family in detail. Genomic analyses of the C. sativa revealed 10 candidate DGAT genes that were classified into four families (DGAT1, DGAT2, DGAT3, WS/DGAT) based on the features of different isoforms. Members of the CsDGAT family were found to be associated with large numbers of cis-acting promoter elements, including plant response elements, plant hormone response elements, light response elements, and stress response elements, suggesting roles for these genes in key processes such as development, environmental adaptation, and abiotic stress responses. Profiling of these genes in various tissues and varieties revealed varying spatial patterns of CsDGAT expression dynamics and differences in expression among C. sativa varieties, suggesting that the members of this gene family likely play distinct functional regulatory functions CsDGAT genes were upregulated in response to cold stress, and significant differences in the mode of regulation were observed when comparing roots and leaves, indicating that CsDGAT genes may play positive roles as regulators of cold responses in hemp while also playing distinct roles in shaping the responses of different parts of hemp seedlings to cold exposure. These data provide a robust basis for further functional studies of this gene family, supporting future efforts to screen the significance of CsDGAT candidate genes to validate their functions to improve hempseed oil composition.

A New Regulatory Network Controls Chilling Injury in Peach Fruit by γ-Aminobutyric Acid

The control of chilling injury in peach fruit by a new regulator network, that exogenous γ-aminobutyric acid (GABA) regulates the metabolisms of polyamines (PAs), the GABA shunt, and proline, is still unclear. This study found that GABA induced an increase in the expression of PpADC and PpODC and a decrease in the expression of PpPAO expression, resulting in the accumulation of PAs. There was also an increase in the expression of PpGAD, which improved GABA content, and an increase in the expression of PpP5CS and PpOAT, which improved proline content. The correlation analysis showed that an increase in PpADC/PpP5CS expression was closely associated with the accumulation of putrescine and that the synergistic increase in the expression of PpODC and PpGAD/PpP5CS/PpOAT was closely related to the accumulation of spermine, proline, and GABA induced by GABA. Importantly, arginine and PpADC played a key role in putrescine accumulation, whereas ornithine and PpODC/PpOAT played a crucial role in the synergistic accumulation of spermine, proline, and GABA induced by GABA. This study provides new information on GABA-induced cold tolerance in peach fruit.

Amelioration of Chilling Injury by Fucoidan in Cold-Stored Cucumber via Membrane Lipid Metabolism Regulation

Cucumber fruit is very sensitive to chilling injury, which rapidly depreciates their commodity value. Herein, the effect of fucoidan treatment on cucumber under cold stress were investigated. Fucoidan treatment of cold-stored cucumber alleviated the occurrence of chilling injury, delayed weight loss, lowered electrolyte leakage and respiration rate, and retarded malondialdehyde accumulation. Different from the control fruit, fucoidan treated fruit showed a high level of fatty acid unsaturated content, fatty acid unsaturation, and unsaturation index and increased ω-FDAS activity, along with upregulated expression levels of CsSAD and CsFAD genes. Fucoidan reduced the phosphatidic acid content and membrane lipid peroxidation, lowered the phospholipase D (PLD) and lipoxygenase (LOX) activity, and downregulated the expression levels of CsPLD and CsLOX genes. Collectively, fucoidan treatment maintained the integrity of cell membrane in cold-stress cucumbers. The results provide a new prospect for the development of fucoidan as a preservative agent in the low-temperature postharvest storage of cucumbers.

Fucoidan treatment alleviates chilling injury in cucumber by regulating ROS homeostasis and energy metabolism

INTRODUCTION

Chilling injury is a major hindrance to cucumber fruit quality during cold storage.

METHODS AND RESULTS

In this study, we evaluated the effects of fucoidan on fruit quality, reactive oxygen species homeostasis, and energy metabolism in cucumbers during cold storage. The results showed that, compared with the control cucumber fruit, fucoidan-treated cucumber fruit exhibited a lower chilling injury index and less weight loss, as well as reduced electrolyte leakage and malondialdehyde content. The most pronounced effects were observed following treatment with fucoidan at 15 g/L, which resulted in increased 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radical scavenging rates and reduced superoxide anion production rate and hydrogen peroxide content. The expression and activity levels of peroxidase, catalase, and superoxide dismutase were enhanced by fucoidan treatment. Further, fucoidan treatment maintained high levels of ascorbic acid and glutathione, and high ratios of ascorbic acid/dehydroascorbate and glutathione/oxidized glutathione. Moreover, fucoidan treatment increased the activities of ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase and their gene expression. Fucoidan treatment significantly delayed the decrease in ATP and ADP, while preventing an increase in AMP content. Finally, fucoidan treatment delayed the decrease of energy charge and the activities and gene expression of H⁺-ATPase, Ca²⁺-ATPase, cytochrome c oxidase, and succinate dehydrogenase in cucumber fruits.

CONCLUSION

Altogether, our findings indicate that fucoidan can effectively enhance antioxidant capacity and maintain energy metabolism, thereby improving cucumber cold resistance during cold storage.

Dissecting postharvest chilling injury through biotechnology

Paradoxically, refrigerating many fruits and vegetables destroys their quality, and may even accelerate their spoilage. This phenomenon, known as postharvest chilling injury (PCI), affects produce from tropical and subtropical regions and leads to economic and postharvest loss and waste. Low temperatures are used to pause the physiological processes associated with senescence, but upon rewarming, these processes may resume at an accelerated rate. Chilling-injured produce may be discarded for not meeting consumer expectations or may prematurely deteriorate. In this review, we describe progress made in identifying the cellular and molecular processes underlying PCI, and point to advances in biotechnological approaches for ameliorating symptoms. Further, we identify the gaps in knowledge that must be bridged to develop effective solutions to PCI.