Fruit Senescence Research Articles

Melatonin treatment enhances bioactive compound retention, antioxidant activity and shelf‐life of bell pepper (Capsicum annuum L.) during cold storage

SummaryMelatonin (MT), a natural signalling compound derived from tryptophan, has gained significant attention for delaying postharvest ripening and senescence in various fruits and vegetables. In the present study, the effect of MT treatment was evaluated on the postharvest shelf‐life of bell pepper. Fruits were dipped in various MT concentrations (70, 120, 170, 220 μmol L−1) for 20 min and stored at 10 ± 1 °C for 20 days. The bell pepper treated with 120 μmol L−1 MT significantly suppressed respiration, weight loss and delayed chlorophyll degradation. Additionally, MT (120 μmol L−1) treatment reduced loss of firmness, titratable acidity and retained total phenol, flavonoid and ascorbic acid content. It hindered malondialdehyde accumulation by enhanced DPPH radical scavenging and antioxidant enzyme activity like superoxide dismutase, catalase and peroxidase, over the control. Conclusively, 120 μmol L−1 MT prolongs the postharvest shelf‐life of bell pepper by 20 days with superior sensory quality, surpassing the control by 10 days. Therefore, MT treatment is a commercially useful technology for maintaining quality and prolonging the postharvest shelf‐life of bell pepper.

Single-cell and spatial RNA sequencing reveal the spatiotemporal trajectories of fruit senescence

The senescence of fruit is a complex physiological process, with various cell types within the pericarp, making it highly challenging to elucidate their individual roles in fruit senescence. In this study, a single-cell expression atlas of the pericarp of pitaya (Hylocereus undatus) is constructed, revealing exocarp and mesocarp cells undergoing the most significant changes during the fruit senescence process. Pseudotime analysis establishes cellular differentiation and gene expression trajectories during senescence. Early-stage oxidative stress imbalance is followed by the activation of resistance in exocarp cells, subsequently senescence-associated proteins accumulate in the mesocarp cells at late-stage senescence. The central role of the early response factor HuCMB1 is unveiled in the senescence regulatory network. This study provides a spatiotemporal perspective for a deeper understanding of the dynamic senescence process in plants.

Rapid Cooling Delays the Occurring of Core Browning in Postharvest 'Yali' Pear at Advanced Maturity by Inhibiting Ethylene Metabolism.

During the storage and transportation processes, the occurrence of core browning in 'Yali' pear fruit due to adversity injury can be easily mitigated by implementing different cooling methods, especially in advanced maturity fruits. In this study, 'Yali' pears at an advanced maturity stage were subjected to slow cooling and rapid cooling treatment. The quality-related physiological percentage and severity, and the rate of good fruits were determined, and RNA-seq was used to explore the effects of different cooling methods on pathways related to core browning in advanced-maturity pears at the transcriptional level. The results indicated that, compared with slow cooling treatment, rapid cooling significantly inhibited core browning in advanced-maturity 'Yali' pears. Measurements of quality-related physiological indexes suggested that rapid cooling treatment led to higher SSC content, firmness, L* value, and b* value, indicating better brightness, coloration, and higher soluble solid content, which are desirable for commercial sale. Rapid cooling effectively suppressed the physiological metabolism of 'Yali' pears, delaying fruit senescence compared with slow-cooling treatment. Furthermore, the RNA-Seq sequencing results revealed that pathways related to browning are involved in hormone signal transduction pathways, which are associated with resistance and aging processes of pear fruit. In summary, rapid cooling treatment delayed the core browning of advanced maturity of 'Yali' pears, indicating that the core browning of 'Yali' pears is related to the cooling method, and the mechanism of rapid cooling in reducing the core browning of advanced maturity of 'Yali' pears was by delaying the aging process of the fruit. This provides a new perspective for alleviating the core browning of advanced-maturity 'Yali' pears during storage and transportation, and provides a theoretical reference for studying the mechanism of core browning of 'Yali' pears.

Salicylic Acid Spray Delays Sand Pear Fruit Senescence during Room Temperature Shelf Life by Regulating Antioxidant Capacity and Senescence-Related Genes.

'Whangkeumbae' (Pyrus pyrifolia) is a variety of sand pear fruit well-known for its smooth surface and good taste. However, the fruit quality is adversely affected by postharvest ethylene production. Therefore, improving postharvest shelf life by regulating fruit senescence is critical to promoting the 'Whangkeumbae' fruit industry. Here, we investigated the effect of salicylic acid (SA) spray on fruit senescence in sand pears during room temperature shelf life. Exogenous SA reduced polyphenol oxidase (PPO) activity and malondialdehyde (MDA) content during room temperature shelf life. Additionally, SA effectively maintained the fruit skin coloration and increased the activity of antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). SA treatment inhibited PpPPO1 expression and upregulated PpSOD1, PpAPX6, and PpGST2 expression. Furthermore, SA application downregulated the expression of PpACO2, PpEIN3a, PpNCED1, and PpAOC2, while upregulating PpNPR-1, PpTAR2, and PpCOMT1 during room temperature shelf life. SA treatment also influenced cell wall metabolism and modification genes by inhibiting PpPG1, PpPME2, and PpCEL3 and inducing PpPGIP1 expression. Additionally, SA treatment affected sugar and acid metabolism genes and increased the expression of PpSPS1, PpSUS1, PpSOT1, PpTMT4, PpSWEET15, and PpcyNAD-MDH, but suppressed the expression of PpcyNADP-ME. The Pearson correlation analysis indicated that PPO activity and MDA content were positively correlated with the expression of PpPPO1, PpACO2, PpEIN3a, PpNCED1, PpAOC2, PpPG1, PpPME2, PpCEL3, and PpcyNDA-MDH. Conversely, these factors were negatively associated with the activities of SOD, POD, CAT, and APX, as well as the expression levels of PpSOD1, PpPOD1, PpCAT1, PpAPX6, PpGST2, PpNPR-1, PpTAR2, PpCOMT1, PpPGIP1, PpSPS1, PpSUS1, PpSOT1, PpTMT4, PpSWEET15, and PpcyNAD-MDH. Our results reveal that exogenous SA could delay fruit senescence in sand pear fruit by regulating various biochemical and molecular mechanisms and can be used to effectively extend fruit shelf life during room temperature storage. However, further research is necessary to determine whether the fruits sprayed with SA are suitable for direct human consumption.

Melatonin delayed senescence by modulating the contents of plant signalling molecules in postharvest okras.

Okra has been widely cultivated worldwide. Consumers appreciate its nutritional value and delicious taste. However, okra is very perishable after harvest because of rapid senescence and high susceptibility to mechanical injuries, which limits its storage life and reduces consumer acceptance. This study examined the influence of melatonin treatment on senescence process and endogenous plant signalling molecules in postharvest okras. The results indicated that melatonin treatment delayed senescence by increasing the endogenous melatonin content through upregulation of its biosynthetic genes. In addition, the treatment increased the contents of indole-3-acetic acid (IAA) and gibberellin (GA) due to the positive modulation of their metabolic and signalling genes. Furthermore, treated okras exhibited higher levels of γ-aminobutyric acid (GABA) but lower abscisic acid (ABA) content, contributing to the delayed senescence process compared to control. Overall, the findings suggested that melatonin postponed senescence in okras fruit by positively regulating endogenous signalling molecules such as melatonin, IAA, GABA, GA, and ABA.

Effects of 1-methylcyclopropene on skin greasiness and quality of 'Yuluxiang’ pear during storage at 20°C

During storage at 20°C, specific pear cultivars may exhibit a greasy texture and decline in quality due to fruit senescence. Among these varieties, 'Yuluxiang’ is particularly susceptible to peel greasiness, resulting in significant economic losses. Therefore, there is an urgent need for a preservative that can effectively inhibit the development of greasiness. Previous studies have demonstrated the efficacy of 1-methylcyclopropene (1-MCP) in extending the storage period of fruits. We hypothesize that it may also influence the occurrence of postharvest peel greasiness in the 'Yuluxiang’ pears. In this study, we treated 'Yuluxiang’ pears with 1-MCP. We stored them at 20°C while analyzing the composition and morphology of the surface waxes, recording enzyme activities related to wax synthesis, and measuring indicators associated with fruit storage quality and physiological characteristics. The results demonstrate that prolonged storage at 20°C leads to a rapid increase in skin greasiness, consistent with the observed elevations in L*, greasiness score, and the content of total wax and greasy wax components. Moreover, there were indications that cuticular waxes underwent melting, resulting in the formation of an amorphous structure. In comparison to controls, the application of 1-MCP significantly inhibited increments in L* values as well as grease scores while also reducing accumulation rates for oily waxes throughout most stages over its shelf period, additionally delaying transitions from flaky-wax structures towards their amorphous counterparts. During the initial 7 d of storage, several enzymes involved in the biosynthesis and metabolism of greasy wax components, including lipoxygenase (LOX), phospholipase D (PLD), and β-ketoacyl-CoA synthase (KCS), exhibited an increase followed by a subsequent decline. The activity of LOX during early shelf life (0–7 d) and the KCS activity during middle to late shelf life (14–21 d) were significantly suppressed by 1-MCP. Additionally, 1-MCP effectively maintained firmness, total soluble solid (TSS) and titratable acid (TA) contents, peroxidase (POD), and phenylalanine ammonia-lyase (PAL) activities while inhibiting vitamin C degradation and weight loss. Furthermore, it restrained polyphenol oxidase (PPO) activity, ethylene production, and respiration rate increase. These findings demonstrate that 1-MCP not only delays the onset of peel greasiness but also preserves the overall storage quality of 'Yuluxiang’ pear at a temperature of 20°C. This study presents a novel approach for developing new preservatives to inhibit pear fruit peel greasiness and provides a theoretical foundation for further research on pear fruit preservation.

Revealing the specific regulations of nitric oxide on the postharvest ripening and senescence of bitter melon fruit

Bitter melon fruit is susceptible to yellowing, softening, and rotting under room-temperature storage conditions, resulting in reduced commercial value. Nitric oxide (NO) is an important signaling molecule and plays a crucial role in regulating the fruit postharvest quality. In this study, we investigated the effects of NO treatment on changes in sensory and firmness of bitter melon fruit during postharvest storage. Moreover, transcriptomic, metabolomic, and proteomic analyses were performed to elucidate the regulatory mechanisms through which NO treatment delays the ripening and senescence of bitter melon fruit. Our results show that differentially expressed genes (DEGs) were involved in fruit texture (CSLE, β-Gal, and PME), plant hormone signal transduction (ACS, JAR4, and AUX28), and fruit flavor and aroma (SUS2, LOX, and GDH2). In addition, proteins differentially abundant were associated with fruit texture (PLY, PME, and PGA) and plant hormone signal transduction (PBL15, JAR1, and PYL9). Moreover, NO significantly increased the abundance of key enzymes involved in the phenylpropanoid biosynthetic pathway, thus enhancing the disease resistance and alleviating softening of bitter melon fruit. Finally, differential metabolites mainly included phenolic acids, terpenoids, and flavonoids. These results provide a theoretical basis for further studies on the physiological changes associated with postharvest ripening and senescence of bitter melon fruit.

Metabolomics and transcriptomics reveal molecular mechanisms of anthocyanin accumulation in 'Nanhong' pear (Pyrus ussuriensis) peel at different temperatures

The bright red hue of the 'Nanhong' pear's pericarp is a key sensory attribute, yet its susceptibility to discoloration at harvest poses challenges for maintaining its commercial appeal. This study, employs quality metrics, metabolomics, and transcriptomics to examine fruit quality and anthocyanin metabolism, along with gene expression involved in anthocyanin biosynthesis, under dark conditions at 0 °C, 10 °C, 20 °C, and 30 °C for up to 21 d. Findings indicate that 0 °C is optimal for long-term storage, while 10 °C is preferable for retail display. LC-MS/MS identified 42 anthocyanin metabolites cyanidin-3-O-galactoside (cya-3-O-gal) being the primary pigment in the pericarp. Discoloration was primarily associated with cyanidin-type and peonidin-type anthocyanins. Transcriptome analysis identified a large number of differentially expressed genes (DEGs) in different comparison groups, KEGG pathway analysis highlighted the significant enrichment of DEGs in phenylpropane and flavonoid metabolic pathways. Key genes in the anthocyanin synthesis pathway, including PuPAL, PuCHS, PuCHI, PuF3`H, PuANS, and PuDFR were markedly down-regulated at 20 °C and 30 °C. Transcription factors such as AP2/ERF, WRKY, MYB, NAC, C2H2, bHLH,and bZIP played an influential part in this process. The study also established that fruit senescence and high-temperature stress were the primary causes of pericarp discoloration at these temperatures. Consequently, identifying optimal storage conditions that preserve fruit quality, delay senescence, and sustain anthocyanin accumulation is crucial. In this study, storage at 10 °C demonstrated the most favorable outcomes for maintaining the pericarp's red color during the marketing period.

Genome-wide identification of the CONSTANS-LIKE (COL) family and mechanism of fruit senescence regulation by PpCOL8 in sand pear (Pyrus pyrifolia)

Pyrus pyrifolia Nakai ‘Whangkeumbae’ is a sand pear fruit with excellent nutritional quality and taste. However, the industrial development of pear fruit is significantly limited by its short shelf life. Salicylic acid (SA), a well-known phytohormone, can delay fruit senescence and improve shelf life. However, the mechanism by which SA regulates CONSTANS-LIKE genes (COLs) during fruit senescence and the role of COL genes in mediating fruit senescence in sand pear are poorly understood. In this study, 22 COL genes were identified in sand pear, including four COLs (PpCOL8, PpCOL9a, PpCOL9b, and PpCOL14) identified via transcriptome analysis and 18 COLs through genome-wide analysis. These COL genes were divided into three subgroups according to the structural domains of the COL protein. PpCOL8, with two B-box motifs and one CCT domain, belonged to the first subgroup. In contrast, the other three PpCOLs, PpCOL9a, PpCOL9b, and PpCOL14, with similar conserved protein domains and gene structures, were assigned to the third subgroup. The four COLs showed different expression patterns in pear tissues and were preferentially expressed at the early stage of fruit development. Moreover, the expression of PpCOL8 was inhibited by exogenous SA treatment, while SA up-regulated the expression of PpCOL9a and PpCOL9b. Interestingly, PpCOL8 interacts with PpMADS, a MADS-box protein preferentially expressed in fruit, and SA up-regulated its expression. While the production of ethylene and the content of malondialdehyde (MDA) were increased in PpCOL8-overexpression sand pear fruit, the antioxidant enzyme (POD and SOD) activity and the expression of PpPOD1 and PpSOD1 in the sand pear fruits were down-regulated, which showed that PpCOL8 promoted sand pear fruit senescence. In contrast, the corresponding changes were the opposite in PpMADS-overexpression sand pear fruits, suggesting that PpMADS delayed sand pear fruit senescence. The co-transformation of PpCOL8 and PpMADS also delayed sand pear fruit senescence. The results of this study revealed that PpCOL8 can play a key role in pear fruit senescence by interacting with PpMADS through the SA signaling pathway.

LcVHA2 and LcVHA3 positively modulate energy metabolism and reduce pericarp browning in litchi fruit after application of Bacillus siamensis

Pericarp browning, postharvest disease, and a short storage life are the leading causes of economic losses in the litchi industry globally. Energy metabolism plays an integral role in regulating browning, disease resistance, and the shelf-life of litchi fruit. The ability of Bacillus siamensis (N-1) to control postharvest diseases and maintain the quality of a variety of tropical fruits has previously been reported, however its effect on litchi fruit has not been explored. In the present study, we investigated the effect of Bacillus siamensis (N-1) on the postharvest energy metabolism of litchi fruit and its relation to pericarp browning, as well as the expression of energy-related genes. Results indicated that litchi fruit treated with Bacillus siamensis (N-1) exhibited a significant improvement in storability as evidenced by a decrease in the rate of the browning index (BI), color change, rate of weight loss, and laccase (LAC) and polyphenol oxidase (PPO) activity. There was also an increase in the energy status of litchi fruit due to the enhanced activity of Ca2+-ATPase, H+-ATPase, oxidase (CCO), cytochrome C, and succinic dehydrogenase (SDH), as well as the expression of their corresponding genes. LcVHA2 and LcVHA3, two major vacuolar-type H+-ATPase genes, were cloned and characterized. Phylogenetic analysis revealed that these genes are members of the V-ATPase subunit D and E gene family, respectively. Both heterologous (in tomato) and homologous (in litchi) transient overexpression (OE) assays indicated that both LcVHA2 and LcVHA3 have the potential to delay changes in fruit coloration and pericarp browning, but also increase ADP, ATP, and V-H+-ATPase activity, as well as the energy charge (EC) of fruit. Collectively, results indicated that the LcVHA2 and LcVHA3 play a critical role in preventing the browning and senescence of litchi fruit. This study provides new information on the ability of Bacillus siamensis (N-1), which has been previously demonstrated to be an effective postharvest biocontrol agent, to also improve the storage life of litchi fruit.

Enhancement of antioxidant quality by Bacillus siamensis N-1 and the role of LcPOD4 in regulating peel browning and senescence of litchi fruit

Plant peroxidases (POD) are involved in various physiological and biochemical processes. Currently, there are relatively few studies on the role of POD in regulating the antioxidant capacity and senescence of postharvest litchi. In this study, we assessed the effects of Bacillus siamensis strain N-1 on the physiology and antioxidant quality of litchi fruit stored at 25 ℃, and characterized the molecular function of LcPOD4 gene in regulating the senescence of litchi fruit. The results showed that N-1 treatment significantly suppressed the increase in ethylene production, electrolyte leakage, and malondialdehyde (MDA) but did not inhibit the respiration rate of litchi during storage. Meanwhile, N-1-treated fruit maintained higher levels of phenolics, flavonoids, and total antioxidant capacity (T-AOC) and lower levels of superoxide anions (O2-.) and hydrogen peroxide (H2O2). In addition, N-1 treatment enhanced the activity of defense enzymes, including superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR), and phenylalanine ammonia-lyase (PAL). The results of quantitative real-time PCR (qRT-PCR) showed that the expression of nine selected LcPOD genes was induced by N-1 treatment at later stages of litchi storage. LcPOD4 cloned from litchi fruit was located in the cell wall and membrane. Transient overexpression of the LcPOD4 gene in tomato and litchi fruits significantly enhanced POD activity and total phenolic and flavonoid contents while accelerating peel color change in the fruit. Collectively, our results indicate that LcPOD4 may contribute, at least partially, to the enhancement of antioxidant capacity in litchi fruit but does not retard peel browning and senescence.

Modeling the effect of multiple pests on ecosystem services provided by fruit crops: Application to apple

CONTEXTIn agroecosystems, crop pests have long been controlled by the intensive use of synthetic pesticides. To lower the dependency on pesticides, alternative crop protection strategies such as Integrated Pest Management (IPM) and Agroecological Crop Protection (ACP) have been proposed. In this context, it is crucial to consider multiple pests and their effects on host plant functioning and, ultimately, on system performance. OBJECTIVEWe aim to develop a pest-crop model to account for the effect of multiple pests on fruit tree functioning and the resulting ecosystem services provided by an orchard, using apple as a case study. METHODSFirst, we identified possible mechanisms of pest disturbance on apple tree for ten major pests: rosy and woolly apple aphid, codling, oriental and tortrix moths, red mite, powdery mildew, European canker, fire blight and apple scab. We classified them into seven functional groups: resource stealers, leaf area reducers, assimilation rate reducers, water transport reducers, assimilate sappers, fruit senescence accelerators and fruit marketability depreciators. Second, we defined coupling functions for each functional group. These describe the reduction of target variables in an existing fruit tree model (QualiTree), i.e. the variables to which the pest disturbances directly apply, as a function of pest abundances. Parameter values of the coupling functions were estimated based on the literature. Third, we used simulations in standard cultural conditions and a Monte Carlo Bayesian Sensitivity Analysis to test and hierarchize the effect of pests on the variation of nine indicators of four classes of ecosystem services (namely fruit production, climate regulation, soil nitrogen availability and water cycle maintenance and regulation).RESULTS AND CONCLUSIONSOnly four indicators were affected by the considered pests: refractometric index (measuring fruit sugar content), marketable yield, carbon sequestration and water drainage. The variations in refractometric index and in marketable yield were largely explained by the main effects of water transport reducers and fruit senescence accelerators, respectively. The latter also contributed the most to carbon sequestration variation. The variation in water drainage was largely explained by the main effect of mildew, an assimilation rate reducer. SIGNIFICANCEOur approach provides an operational tool to assess the impact of multiple pests on orchard ecosystem services. The model also opens up the possibility of studying the impact of pests in different ecological and technical contexts. For this, it must be coupled with models capable of predicting pest abundances as a function of cultivation practices and biotic and abiotic conditions.

Anthocyanin treatment delays the senescence of blueberry fruit by regulating abscisic acid and anthocyanin synthesis processes

Abstract Objectives The purpose of this work was to examine the general effects of exogenous anthocyanins treatment on the synthesis of abscisic acid (ABA) and anthocyanin in blueberry fruit during postharvest storage under room temperature conditions. Materials and Methods Fresh blueberry fruit were treated with 3.0 g/L anthocyanins and stored at room temperature to investigate the effects of the treatment on fruit firmness and nutritional quality. The fruit firmness, ABA content, anthocyanin content and the relative expression levels of key genes were evaluated. Results The results demonstrated that anthocyanins treatment decreased the ABA level by inhibiting the expression of the VcNCED1 gene implicated in ABA synthesis. At the same time, the treatment increased the content of endogenous anthocyanin by promoting the expression of anthocyanin biosynthesis genes such as VcC4H, VcF3H, VcF3’5’H, VcANS, and VcAT. Conclusions Postharvest anthocyanins treatment promoted the synthesis of endogenous anthocyanin, inhibited the accumulation of endogenous ABA, and delayed the senescence of blueberries by inhibiting fruit softening and the accumulation of active oxygen.

Bordeaux mixture accelerates ripening, delays senescence, and promotes metabolite accumulation in jujube fruit

Abstract The old, but eco-friendly pesticide, Bordeaux mixture (Bm), is widely used in agriculture. Here, the effects of Bm on preharvest fruit ripening, and postharvest senescence of fruit and the accumulation of antioxidants were studied in Ziziphus jujuba. A 200× dilution of Bm enhanced preharvest ripening and retarded jujube fruit postharvest senescence. Treatment with Bm increased the reddening index and promoted the accumulation of total phenolics (TP) and the total antioxidant capacity (TAC) in preharvest fruit. However, this Bm-accelerated ripening could be partly reversed using dimethylthiourea (DMTU), a specific scavenger of reactive oxygen species. Compared with preharvest fruit, Bm treatment decreased weight loss and decay and increased firmness in postharvest fruit. Similarly, Bm-delayed senescence was partly reversed using dimethylthiourea. Moreover, the decrease in TP and TAC during storage was partly impeded by Bm. A higher H2O2 content was detected in preharvest fruit than in postharvest fruit. Moreover, this Bm-induced H2O2 accumulation was significantly mitigated using dimethylthiourea. Interestingly, both preharvest and postharvest spraying with Bm significantly enhance copper and calcium accumulation in fruit. Thus, Bm can be widely used before or after harvest to improve fruit quality.

Tannic Acid and Ca2+ Double-Crosslinked Alginate Films for Passion Fruit Preservation.

In this study, the interaction of different concentrations of tannic acid (TA) (10%, 20%, and 30% w/w) and Ca2+ with alginate (SA) was utilized to create double-crosslinked SA films. The resulting films were evaluated for their optical, mechanical, water resistance, and barrier properties, and their microstructure and intermolecular interactions were also characterized. The SA films containing 20% TA showed the best mechanical properties, with an observed increase in tensile strength of 22.54%. In terms of water vapor permeability, the SA film containing 30% TA exhibited the highest barrier property, which was 25.36% higher than that of the pure SA film. Moreover, TA demonstrated a strong UV absorption ability, resulting in a nearly 0% UV transmittance of the SA film at 280 nm. It can be seen that SA films containing 20% TA have excellent barrier and mechanical properties, and the development of such films will be applied to the storage and packaging of fresh food. It is worth noting that this work also investigated the effect of SA coatings containing different concentrations of TA on the preservation of passion fruits for 7 days. The results revealed that passion fruits treated with SA coatings containing a 30% TA concentration maintained a better appearance on the 7th day and had the lowest weight loss and crumpling indices of approximately 8.98% and 2.17, respectively, compared to the other treatment groups. Therefore, based on the overall results, the addition of 30% TA to SA coatings proved to be more effective and can be considered a promising approach for delaying fruit senescence and decay.

Understanding the Fermentation Potentiality For Gibberellic Acid (GA3) Production Using Fungi.

Gibberellins represent an important group of potent phytohormones, growth-promoting, closely related diterpenoid acids biologically derived from tetracyclic diterpenoid hydrocarbon. Among these, gibberellic acid (GA3) has received the greatest attention. GA3 is a highly valued plant growth regulator which has various applications in agriculture. It is extensively used for beneficial effects including stem elongation, elimination of dormancy, sex expression, seed germination, flowering, and fruit senescence. Along with plants, many microbes are also producing GA3 as their secondary metabolite, and among these, fungi are reported to produce a higher amount of GA3. Fermentation technology based on submerged fermentation and solid-state fermentation for the production of GA3 has been used with its merits and demerits using Fusarium moniliforme fungus in the industry. Several mathematical models and optimization tools were also designed for enhancing the fermentative yield by researchers. The detailed analysis is essential to understand all the fermentation aspects, various unit parameters, process operation approaches, reduction in cost, and assessment of the possible uses of these models in the production of GA3 for higher yield. Recently, exclusive research is executed to lower down the production cost of GA3 approaching various strategies.

CRISPR/Cas9-mediated mutation of Eil1 transcription factor genes affects exogenous ethylene tolerance and early flower senescence in Campanula portenschlagiana.

Improving tolerance to ethylene-induced early senescence of flowers and fruits is of major economic importance for the ornamental and food industry. Genetic modifications of genes in the ethylene-signalling pathway have frequently resulted in increased tolerance but often with unwanted side effects. Here, we used CRISPR/Cas9 to knockout the function of two CpEil1 genes expressed in flowers of the diploid ornamental plant Campanula portenschlagiana. The ethylene tolerance in flowers of the primary mutants with knockout of only one or all four alleles clearly showed increased tolerance to exogenous ethylene, although lower tolerance was obtained with one compared to four mutated alleles. The allele dosage effect was confirmed in progenies where flowers of plants with zero, one, two, three and four mutated alleles showed increasing ethylene tolerance. Mutation of the Cpeil1 alleles had no significant effect on flower longevity and endogenous flower ethylene level, indicating that CpEil1 is not involved in age-dependent senescence of flowers. The study suggests focus on EIN3/Eils expressed in the organs subjected to early senescence for obtaining tolerance towards exogenous ethylene. Furthermore, the observed allelic dosage effect constitutes a key handle for a gradual regulation of sensitivity towards exogenous ethylene, simultaneously monitoring possibly unwanted side effects.

Acidic electrolyzed water treatment delays the senescence of ‘Lingwu long’ jujube fruit during cold storage by regulating energy and respiratory metabolism

Jujube fruit may rapidly undergo maturity and senescence during storage, seriously affecting its commercialization. The study aimed to evaluate the role of acidic electrolyzed water (AEW) on energy and respiratory metabolism, and senescence in jujube fruit during cold storage. The results indicated that AEW improved ATP content and energy charge via increasing succinate dehydrogenase, cytochrome C oxidase, H+-ATPase, and Ca2+-ATPase activities and delayed jujube fruit senescence. The treatment was found to improve the activities of nicotinamide adenine dinucleotide kinase, 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase, and the content of NADPH, and reduce oxidative stress. Transcriptome analysis suggested that AEW regulated the expression of the genes associated with glycolysis, citrate cycle, pentose phosphate pathway, oxidative phosphorylation, ROS metabolism, transcription factors, phenylpropane biosynthesis, cell wall metabolism, and plant hormone signal transduction. Therefore, we concluded that AEW may delay the senescence of postharvest jujube fruit by regulating expression of the relevant genes and metabolic pathways.

Phenyllactic acid maintains the storage quality of ‘Zaosu’ pears by regulating respiration and energy metabolism

Respiration and energy metabolism are intricately linked to the quality and senescence of fruit after harvest. This investigation was carried out to examine alternations in quality parameters, respiration, and energy metabolism of ‘Zaosu’ pears subsequent to phenyllactic acid immersion. Results demonstrated that phenyllactic acid treatment led to a reduction in L* , a* , b* values, ΔE, and mass loss. Additionally, it maintained ascorbic acid, reducing sugar, soluble sugar, soluble solids, and chlorophyll contents; delayed the decrease in flesh firmness and titratable acidity of pears. The activities and gene expressions of glucose-6-phosphate dehydrogenase, glucose phosphate isomerase, hexokinase, nicotinamide adenine dinucleotide kinase, cytochrome C oxidase, and succinate dehydrogenasepears in pears were enhanced by phenyllactic acid. Moreover, phenyllactic acid promoted PbPK, PbAOX, PbH+-ATPase, and PbCa2+-ATPase expressions, while inhibiting malate dehydrogenase activity and the expressions of PbPFK and PbMDH in pears. Phenyllactic acid also led to a decrease in the levels of nicotinamide adenine dinucleotide hydrogen and nicotinamide adenine dinucleotide, while causing an increase in the levels of nicotinamide adenine dinucleotide phosphate hydrogen and nicotinamide adenine dinucleotide phosphate within the fruit. Collectively, postharvest phenyllactic acid treatment can effectively preserve the storage quality of ‘Zaosu’ pears by regulating the activity and gene expression of the key enzymes involved in respiration and energy metabolism.

Alleviatory effects of salicylic acid on postharvest softening and cell wall degradation of 'Jinshayou' pummelo (Citrus maxima Merr.): A comparative physiological and transcriptomic analysis.

The regulatory mechanisms underlying the salicylic acid (SA)-mediated inhibition of senescence in pummelo fruit, the largest known citrus variety, remain unclear. Herein, postharvest 0.3% SA treatment was demonstrated to delay postharvest 'Jinshayou' pummelo senescence, as evidenced by the inhibitions in firmness loss, electrolyte leakage increase, and color change. Using comparative transcriptomic data, a total of 4367, 3769, and 1659 DEGs were identified between CK0 and CK60, CK0 and SA60, and CK60 and SA60, respectively. Further GO analysis revealed that DEGs were mainly implicated in the processes of cell wall modification and phenylpropanoid pathway during fruit senescence. More importantly, postharvest exogenous 0.3% SA treatment was observed to inhibit CWDEs activities and their encoding gene expression, retain higher protopectin, cellulose, and hemicelluloses contents, as well as reduce WSP content, thus maintaining cell wall structure. These findings collectively indicated that postharvest SA treatment was a green and useful preservative for alleviating fruit senescence and prolonging the storage life of harvested 'Jiashayou' pummelo fruit.