Advances in chilling injury of postharvest fruit and vegetable: Extracellular ATP aspects

ATP homeostasis and signaling in plants

ATP is the primary form of energy for plants, and a shortage of cellular ATP is generally acknowledged to pose a threat to plant growth and development, stress resistance, and crop quality. The overall metabolic processes that contribute to the ATP pool, from production, dissipation, and transport to elimination, have been studied extensively. Considerable evidence has revealed that in addition to its role in energy supply, ATP also acts as a regulatory signaling molecule to activate global metabolic responses. Identification of the eATP receptor DORN1 contributed to a better understanding of how plants cope with disruption of ATP homeostasis and of the key points at which ATP signaling pathways intersect in cells or whole organisms. The functions of SnRK1α, the master regulator of the energy management network, in restoring the equilibrium of the ATP pool have been demonstrated, and the vast and complex metabolic network mediated by SnRK1α to adapt to fluctuating environments has been characterized. This paper reviews recent advances in understanding the regulatory control of the cellular ATP pool and discusses possible interactions among key regulators of ATP-pool homeostasis and crosstalk between iATP/eATP signaling pathways. Perception of ATP deficit and modulation of cellular ATP homeostasis mediated by SnRK1α in plants are discussed at the physiological and molecular levels. Finally, we suggest future research directions for modulation of plant cellular ATP homeostasis.

Comprehensive review: Effects of climate change and greenhouse gases emission relevance to environmental stress on horticultural crops and management

Global climate change exerts a significant impact on sustainable horticultural crop production and quality. Rising Global temperatures have compelled the agricultural community to adjust planting and harvesting schedules, often necessitating earlier crop cultivation. Notably, climate change introduces a suite of ominous factors, such as greenhouse gas emissions (CGHs), including elevated temperature, increased carbon dioxide (CO2) concentrations, nitrous oxide (N2O) and methane (CH4) ozone depletion (O3), and deforestation, all of which intensify environmental stresses on crops. Consequently, climate change stands poised to adversely affect crop yields and livestock production. Therefore, the primary objective of the review article is to furnish a comprehensive overview of the multifaceted factors influencing horticulture production, encompassing fruits, vegetables, and plantation crops with a particular emphasis on greenhouse gas emissions and environmental stressors such as high temperature, drought, salinity, and emission of CO2. Additionally, this review will explore the implementation of novel horticultural crop varieties and greenhouse technology that can contribute to mitigating the adverse impact of climate change on agricultural crops.

Dissecting postharvest chilling injuries in pome and stone fruit through integrated omics

Lowering the storage temperature is an effective method to extend the postharvest and shelf life of fruits. Nevertheless, this technique often leads to physiological disorders, commonly known as chilling injuries. Apples and pears are susceptible to chilling injuries, among which superficial scald is the most economically relevant. Superficial scald is due to necrotic lesions of the first layers of hypodermis manifested through skin browning. In peaches and nectarines, chilling injuries are characterized by internal symptoms, such as mealiness. Fruits with these aesthetic or compositional/structural defects are not suitable for fresh consumption. Genetic variation is a key factor in determining fruit susceptibility to chilling injuries; however, physiological, or technical aspects such as harvest maturity and storage conditions also play a role. Multi-omics approaches have been used to provide an integrated explanation of chilling injury development. Metabolomics in pome fruits specifically targets the identification of ethylene, phenols, lipids, and oxidation products. Genomics and transcriptomics have revealed interesting connections with metabolomic datasets, pinpointing specific genes linked to cold stress, wax synthesis, farnesene metabolism, and the metabolic pathways of ascorbate and glutathione. When applied to Prunus species, these cutting-edge approaches have uncovered that the development of mealiness symptoms is linked to ethylene signaling, cell wall synthesis, lipid metabolism, cold stress genes, and increased DNA methylation levels. Emphasizing the findings from multi-omics studies, this review reports how the integration of omics datasets can provide new insights into understanding of chilling injury development. This new information is essential for successfully creating more resilient fruit varieties and developing novel postharvest strategies.

Overview of Food Preservation and Traceability Technology in the Smart Cold Chain System

According to estimates by the Food and Agriculture Organization of the United Nations (FAO), about a third of all food produced for human consumption in the world is lost or wasted-approximately 1.3 billion tons. Among this, the amount lost during the storage stage is about 15-20% for vegetables and 10-15% for fruits. It is 5-10% for vegetables and fruits during the distribution stage, resulting in a large amount of resource waste and economic losses. At the same time, the global population affected by hunger has reached 828 million, exceeding one-tenth of the total global population. The improvement of the cold chain system will effectively reduce the amount of waste and loss of food during the storage and transportation stages. Firstly, this paper summarizes the concept and development status of traditional preservation technology; environmental parameter sensor components related to fruit and vegetable spoilage in the intelligent cold chain system; the data transmission and processing technology of the intelligent cold chain system, including wireless network communication technology (WI-FI) and cellular mobile communication; short-range communication technology, and the low-power, wide-area network (LPWAN). The smart cold chain system is regulated and optimized through the Internet of Things, blockchain, and digital twin technology to achieve the sustainable development of smart agriculture. The deep integration of artificial intelligence and traditional preservation technology provides new ideas and solutions for the problem of food waste in the world. However, the lack of general standards and the high cost of the intelligent cold chain system are obstacles to the development of the intelligent cold chain system. Governments and researchers at all levels should strive to highly integrate cold chain systems with artificial intelligence technology, establish relevant regulations and standards for cold chain technology, and actively promote development toward intelligence, standardization, and technology.

Reduction of Membrane Lipid Metabolism in Postharvest Hami Melon Fruits by n-Butanol to Mitigate Chilling Injury and the Cloning of Phospholipase D-β Gene

To investigate the effect of n-butanol on postharvest membrane lipid metabolism of Hami melon (Cucumis melo 'Hami'), the fruits were soaked in a 1.0% solution of n-butanol for 30 min with water as the control. Symptoms of chilling injury were observed regularly, and the indices related to permeability and membrane lipid metabolism of pericarp cells were measured. The results showed that treatment with n-butanol inhibited the increase in chilling injury index, membrane permeability, and malondialdehyde content of Hami melon fruits, promoted an increase in the contents of phosphatidyl alcohol and unsaturated fatty acids, such as linoleic acid, linolenic acid, oleic acid (except 14 d), and erucic acid (28-42 d), and decreased the content of saturated fatty acids, stearic acid (0-28 d), phosphatidic acid (except for 21 d), and the key enzymes of membrane lipid metabolism compared with the control. The activities of phospholipase D (PLD) and lipoxygenase (LOX) and the downregulation of the levels of expression CmPLD-β and CmLOX (42 d only) genes reduced the chilling injury index of Hami melon and alleviated the further expansion of chilling injury symptoms in the fruits. We also cloned the key gene of membrane lipid metabolism CmPLD-β, which was obtained by pre-transcriptome screening of the pericarp. We found that CmPLD-β of Hami melon had the closest affinity with cucumber (CsXP5), indicating that the CmPLD-β gene of Hami melon was functionally similar to that of cucumber. In addition, a two-fold alignment analysis of CmPLD-β and CmXP5 base sequences indicated that the base sequences of the two promoter regions differed from each other.

Nitric oxide modulates folate-mediated one-carbon metabolism and mitochondrial energy levels of peaches during cold storage

Folate-mediated one-carbon metabolism (FOCM) is closely associated with postharvest preservation. This study investigated the effects of exogenous nitric oxide (NO) on FOCM, storage quality, energy metabolism, and mitochondrial membrane integrity in cold-storage peach fruit. In this experiment, peaches were soaked with 1.5 mmol L^-1S-nitrosoglutathione (GSNO) as NO donor, and the negative treatment (NT) solution containing 5 μmol L^-1 carboxy-PTIO (c-PTIO, NO scavenger), 200 μmol L^-1 N^G-Nitro-_L-arginine methyl ester (_L-NAME, NO synthase-like enzyme inhibitor), and 200 μmol L^-1 sodium tungstate dihydrate (nitrate reductase inhibitor) and stored at 0°C. The results showed that NO decreased the activity of S-adenosylmethionine synthase and S-adenosylhomocysteine hydrolase and increased the activity of methionine sulfoxide reductase A, as well as the content of N5-methyl-THF, the ratio of tetrahydrofolate (THF), homocysteine, methionine, S-adenosylmethionine (SAM), and SAM to S-adenosylhomocysteine compared with the control, indicating that NO effectively increased FOCM flux by affecting the activity of FOCM enzymes. Meanwhile, NO increased the activities of H⁺-ATPase, Ca²⁺-ATPase, cytochrome c oxidase, succinate dehydrogenase, and the contents of adenosine triphosphate and adenosine diphosphate, and maintained high energy charge in peaches during storage. NO retarded the increase in mitochondrial permeability transition, reactive oxygen species content, and the decrease in mitochondrial membrane fluidity, membrane potential, and swelling. NT treatment exhibited the opposite results. In conclusion, these results suggested that NO could induce the accumulation of folate and FOCM flux and maintain mitochondrial energy levels, which might be responsible for maintaining the quality of peaches during cold storage.