Increase In Ethylene Production Research Articles

Tomato Synaptotagmin F accelerates fruit ripening, shortens fruit shelf-life and increases susceptibility to Penicillium expansum

Synaptotagmins (SYTs), initially identified as calcium sensors for regulating synaptic vesicle exocytosis and endocytosis in mammalian neurons, play crucial role in biotic and abiotic stresses in plants. However, the function of SYTs in fruit ripening is unclear. In this study, a tomato Synaptotagmins gene, SlSYTF, was found to accelerate tomato fruit ripening. SlSYTF encodes an endoplasmic reticulum localized protein whose transcription is continuously enhanced during fruit ripening. Overexpression SlSYTF in tomato resulted in accelerated ripening progress, increased carotenoid content as well as decreased the firmness of tomato fruit, whereas the mutant slsytf-c exhibited the opposite phenotype. Importantly, SlSYTF could increase ethylene production by activating the expression of ethylene synthesis genes and prompt cell wall degradation by increasing pectinase and cellulase activities. Nevertheless, the accelerated cell wall degradation and thinned cuticle due to SlSYTF results in reduced shelf life and pathogen resistance. Collectively, we revealed a new SYTs gene that plays a dual role in tomato fruit ripening and pathogen response. This finding may shed new light on the relationship between maturation and immunity.

Methyl jasmonate activated regulatory module Ma14-3-3e-MbHLH130-MbACO13/MbACS7 promoting ethylene biosynthesis and fruit ripening in banana

Methyl jasmonate (MeJA), an important phytohormone, plays a vital role in many biological processes. However, its effect and mechanism in regulating ethylene synthesis and fruit ripening in banana remain unknown. In this research, we found that exogenous MeJA accelerated postharvest ripening of banana, which coincided with increased ethylene production and upregulation of MbACS7 and MbACO13 expression. MabHLH130 directly interacted with and stimulated the transcription of MbACS7 and MbACO13. Additionally, MabHLH130 interacted with Ma14-3-3e through the RHSSSP motif. Overexpression of either MabHLH130 or Ma14-3–3e in tomato promoted ethylene production and fruit ripening, and this effect was enhanced by exogenous MeJA treatment. Furthermore, the Ma14-3–3e-MabHLH130 interaction module activated MbACS7 and MbACO13 transcription, which was enhanced by exogenous MeJA treatment. Taken together, these results demonstrated that the MeJA-responsive Ma14-3–3e-MabHLH130-MbACS7/MbACO13 module promoted ethylene biosynthesis and fruit ripening in bananas, providing valuable genetic targets for breeding programs aimed at extending fruit shelf-life.

Effect of postharvest cold storage and subsequent shelf-life on fruit quality and endogenous phytohormones in nectarine fruit

Cold storage is the main approach to extend the postharvest storage period of nectarines. The objective of this study was to investigate fruit quality (flavor and nutrition) and endogenous phytohormone changes and their related transcriptional changes in nectarine fruit after cold storage and subsequent shelf-life, which was performed metabolome, transcriptome and physiological analysis. Cold storage led to irreversible flavor loss due to the inhibition of aroma biosynthesis genes at low temperature. Sugar and organic acid content was affected, with an increase in glucose, fructose and malic acid, and a decrease in sorbitol and citric acid after cold storage or shelf-life. For fruit nutritional quality, total flavonoids or total carotenoids was not significantly affected by cold storage, whereas shelf-life process enhanced their accumulation. The activities of key enzymes for flavonoid biosynthesis, PAL and C4H, were enhanced during the shelf-life process, resulting in a significant increase in flavonoids and enhanced free radicals scavenging capacity. Meanwhile, shelf-life process increased carotenoids content by improving the expression of carotenoid biosynthesis genes PSY, ZDS and ZISO. Additionally, cold storage significantly increased the IAA content and ethylene production, thereby inducing the up-regulation of related signaling transduction genes. The shelf-life process further increased ethylene production, as well as salicylic acid and jasmonic acid content. This study unravels these crucial physiological and associated transcriptional changes of nectarines after cold storage, and may provide a theoretical foundation for improving fruit quality of peaches after cold storage.

Discovery of functional PRRs for the fungal elicitor Xyn11/eix in Prunus fruit trees

Pattern-triggered immunity (PTI) is a critical defense mechanism employed by plants against pathogen attacks. This study explores the role of PTI induced by the Xyn11/eix fungal elicitor in two commercially valuable Rosaceae species, Prunus persica (peach) and Prunus avium (sweet cherry). Our findings demonstrate that Xyn11/eix triggers two specific defense responses: the increase in ethylene production and the induction of cell death. Furthermore, Xyn11/eix-mediated PTI significantly reduces the susceptibility to Botrytis cinerea infection in both species. The study reveals changes in gene expression patterns after Xyn11/eix treatment. Notably, ACO1 and SARDEF1 genes, involved in ethylene and salycilic acid biosynthesis, respectively, are upregulated in P. persica, but not in P. avium at the time point analyzed. This result suggests a potential role for the ethylene and salicylic acid signaling in Xyn11/mix-mediated PTI in P. persica. Additionally, the research identified functional orthologues of LeEIX2, the receptor for Xyn11/eix in Solanum lycopersicum, within both Prunes genomes. Altogether, these results suggest a remarkable functional convergence between Rosaceae and Solanaceae plants in the Xyn11/eix mediated defense responses although not at the transcriptional level, and opens new avenues for developing novel disease control strategies for stone fruits.

Interrogation of Oxidative Pulsed Methods for the Stabilization of Copper Electrodes for CO2 Electrolysis.

Using copper (Cu) as an electrocatalyst uniquely produces multicarbon products (C2+-products) during the CO2 reduction reaction (CO2RR). However, the CO2RR stability of Cu is presently 3 orders of magnitude shorter than required for commercial operation. One means of substantially increasing Cu catalyst lifetimes is through periodic oxidative processes, such as cathodic-anodic pulsing. Despite 100-fold improvements, these oxidative methods only delay, but do not circumvent, degradation. Here, we provide an interrogation of chemical and electrochemical Cu oxidative processes to identify the mechanistic processes leading to stable CO2RR through electrochemical and in situ Raman spectroscopy measurements. We first examine chemical oxidation using an open-circuit potential (OCP), identifying that copper oxidation is regulated by the transient behavior of the OCP curve and limited by the rate of the oxygen reduction reaction (ORR). Increasing O2 flux to the cathode subsequently increased ORR rates, both extending lifetimes and reducing "off" times by 3-fold. In a separate approach, the formation of Cu2O is achieved through electrochemical oxidation. Here, we establish the minimum electrode potentials required for fast Cu oxidation (-0.28 V vs Ag/AgCl, 1 M KHCO3) by accounting for transient local pH changes and tracking oxidation charge transfer. Lastly, we performed a stability test resulting in a 20-fold increase in stable ethylene production versus the continuous case, finding that spatial copper migration is slowed but not mitigated by oxidative pulsing approaches alone.

A Phytotoxin with Selective Herbicidal Activity and Related Metabolites from the Phytopathogenic Fungus Bipolaris cookei SYBL03.

Weeds are a serious threat to crop production, and the utilization of secondary metabolites of phytopathogenic fungi is considered to be an effective method of weed control. In this study, eight compounds were isolated and purified from the mycelium and fermentation broth extracts of Bipolaris cookei SYBL03. The compounds (1-8), except 2 and 6, are reported for the first time from this genus. The herbicidal activities of compounds 1-8 were studied by evaluating their effects on the seed germination and seedling growth of monocotyledonous and dicotyledonous weeds. The results indicated that compound 7 (Cyclo-N-methylphenylalanyltryptophenyl, cNMPT) exhibited a concentration-dependent dual effect on the growth of weed seedlings and selective herbicidal activity against dicotyledonous weeds. We further investigated the morphological and physiological responses of roots of Amaranthus retroflexus, a dicotyledonous weed, to compound 7. Some changes were found in seedlings grown in 400 μg/mL compound 7 solution for 96 h, such as shortening and swelling of elongation zone cells, reduced number and length of root hairs, damage and wrinkling of the root surface, occurrence of electrolyte leakage, and an increase in ethylene content. These results suggest that compound 7 may exert herbicidal activity by causing stress to weed seedlings. Increased ethylene production could be involved in the response of plants to compound 7.

CmPIF8-CmERF27-CmACS10-mediated ethylene biosynthesis modulates red light-induced powdery mildew resistance in oriental melon.

Powdery mildew is a serious fungal disease in protected melon cultivation that affects the growth, development and production of melon plants. Previous studies have shown that red light can improve oriental melon seedlings resistance to powdery mildew. Here, after inoculation with Podosphaera xanthii, an obligate fungal pathogen eliciting powdery mildew, we found that red light pretreatment increased ethylene production and this improved the resistance of melon seedlings to powdery mildew, and the ethylene biosynthesis gene CmACS10 played an important role in this process. By analysing the CmACS10 promoter, screening yeast one-hybrid library, it was found that CmERF27 positively regulated the expression of CmACS10, increased powdery mildew resistanceand interacted with PHYTOCHROME INTERACTING FACTOR8 (CmPIF8) at the protein level to participate in the regulation of ethylene biosynthesis to respond to the red light-induced resistance to P. xanthii, Furthermore, CmPIF8 also directly targeted the promoter of CmACS10, negatively participated in this process. In summary, this study revealed the specific mechanism by which the CmPIF8-CmERF27-CmACS10 module regulates red light-induced ethylene biosynthesis to resist P. xanthii infection, elucidate the interaction between light and plant hormones under biological stress, provide a reference and genetic resources for breeding of disease-resistant melon plants.

Interaction among homeodomain transcription factors mediates ethylene biosynthesis during pear fruit ripening.

Fruit ripening is manipulated by the plant phytohormone ethylene in climacteric fruits. While the transcription factors (TFs) involved in ethylene biosynthesis and fruit ripening have been extensively studied in tomato, their identification in pear remains limited. In this study, we identified and characterized a HOMEODOMAIN TF, PbHB.G7.2, through transcriptome analysis. PbHB.G7.2 could directly bind to the promoter of the ethylene biosynthetic gene, 1-aminocyclopropane-1-carboxylic acid synthase (PbACS1b), thereby enhancing its activity and resulting in increased ethylene production during pear fruit ripening. Yeast-two-hybrid screening revealed that PbHB.G7.2 interacted with PbHB.G1 and PbHB.G2.1. Notably, these interactions disrupted the transcriptional activation of PbHB.G7.2. Interestingly, PbHB.G1 and PbHB.G2.1 also bind to the PbACS1b promoter, albeit different regions from those bound by PbHB.G7.2. Moreover, the regions of PbHB.G1 and PbHB.G2.1 involved in their interaction with PbHB.G7.2 differ from the regions responsible for binding to the PbACS1b promoter. Nonetheless, these interactions also disrupt the transcriptional activation of PbHB.G1 and PbHB.G2.1. These findings offer a new mechanism of ethylene biosynthesis during climacteric fruit ripening.

TSPO-induced degradation of the ethylene receptor RhETR3 promotes salt tolerance in rose (Rosa hybrida).

The gaseous plant hormone ethylene regulates plant development, growth, and responses to stress. In particular, ethylene affects tolerance to salinity; however, the underlying mechanisms of ethylene signaling and salt tolerance are not fully understood. Here, we demonstrate that salt stress induces the degradation of the ethylene receptor ETHYLENE RESPONSE 3 (RhETR3) in rose (Rosa hybrid). Furthermore, the TspO/MBR (Tryptophan-rich sensory protein/mitochondrial benzodiazepine receptor) domain-containing membrane protein RhTSPO interacted with RhETR3 to promote its degradation in response to salt stress. Salt tolerance is enhanced in RhETR3-silenced rose plants but decreased in RhTSPO-silenced plants. The improved salt tolerance of RhETR3-silenced rose plants is partly due to the increased expression of ACC SYNTHASE1 (ACS1) and ACS2, which results in an increase in ethylene production, leading to the activation of ETHYLENE RESPONSE FACTOR98 (RhERF98) expression and, ultimately accelerating H2O2 scavenging under salinity conditions. Additionally, overexpression of RhETR3 increased the salt sensitivity of rose plants. Co-overexpression with RhTSPO alleviated this sensitivity. Together, our findings suggest that RhETR3 degradation is a key intersection hub for the ethylene signalling-mediated regulation of salt stress.

Calmodulin-like protein CML15 interacts with PP2C46/65 to regulate papaya fruit ripening via integrating calcium, ABA and ethylene signals.

It is well known that calcium, ethylene and abscisic acid (ABA) can regulate fruit ripening, however, their interaction in the regulation of fruit ripening has not yet been fully clarified. The present study found that the expression of the papaya calcium sensor CpCML15 was strongly linked to fruit ripening. CpCML15 could bind Ca2+ and served as a true calcium sensor. CpCML15 interacted with CpPP2C46 and CpPP2C65, the candidate components of the ABA signalling pathways. CpPP2C46/65 expression was also related to fruit ripening and regulated by ethylene. CpCML15 was located in the nucleus and CpPP2C46/65 were located in both the nucleus and membrane. The interaction between CpCML15 and CpPP2C46/65 was calcium dependent and further repressed the activity of CpPP2C46/65 in vitro. The transient overexpression of CpCML15 and CpPP2C46/65 in papaya promoted fruit ripening and gene expression related to ripening. The reduced expression of CpCML15 and CpPP2C46/65 by virus-induced gene silencing delayed fruit colouring and softening and repressed the expression of genes related to ethylene signalling and softening. Moreover, ectopic overexpression of CpCML15 in tomato fruit also promoted fruit softening and ripening by increasing ethylene production and enhancing gene expression related to ripening. Additionally, CpPP2C46 interacted with CpABI5, and CpPP2C65 interacted with CpERF003-like, two transcriptional factors in ABA and ethylene signalling pathways that are closely related to fruit ripening. Taken together, our results showed that CpCML15 and CpPP2Cs positively regulated fruit ripening, and their interaction integrated the cross-talk of calcium, ABA and ethylene signals in fruit ripening through the CpCML15-CpPP2Cs-CpABI5/CpERF003-like pathway.

The transcription factor PbbHLH164 is destabilized by PbRAD23C/D.1 and mediates ethylene biosynthesis during pear fruit ripening

The phytohormone ethylene plays an important role in climacteric fruit ripening. However, the knowledge on molecular regulation of ethylene biosynthesis remains limited in pear fruit. Herein, a new basic helix-loop-helix transcription factor, PbbHLH164, was identified based on the transcriptome analysis of different developing and ripening fruits of two pear cultivars ‘Sucui No.1’ and ‘Cuiguan’. PbbHLH164 was more highly expressed in ripening fruit than in developing fruit and positively correlated with ethylene production in both cultivars. PbbHLH164 could directly bind to the promoter of 1-aminocyclopropane-1-carboxylate synthase, PbACS1b, to enhance the expression, leading to the increase of ethylene production and the acceleration of fruit ripening. Interestingly, PbbHLH164 physically interacted with an ubiquitin-like/ubiquitin-associated protein PbRAD23C/D.1, and the interaction of PbbHLH164 with PbRAD23C/D.1 attenuated the function of PbbHLH164 in enhancing the activity of the PbACS1b promoter. Notably, PbRAD23C/D.1 was involved in the degradation of PbbHLH164, and this degradation was inhibited by an ubiquitin proteasome inhibitor MG132. Different from PbbHLH164, PbRAD23C/D.1 was more highly expressed in developing fruit than in ripening fruit of both cultivars. These results suggest that the increase of ethylene production during pear fruit ripening results from the up-regulated expression of PbbHLH164 and the down-regulated expression of PbRAD23C/D.1. This information provided new insights into the molecular regulation of ethylene biosynthesis during fruit ripening.

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.

Layer by layer application of chitosan and carboxymethyl cellulose coatings delays ripening of mango fruit by suppressing cell wall polysaccharides disassembly

Mango is a climacteric fruit that ripens quickly after harvest due to its climacteric nature. Edible coatings have been reported to delay the ripening of various harvested fruit. The efficacy of the applied edible coatings could be improved by using in combination as a layer-by-layer (LBL) approach. So, the influence of LBL application of chitosan (CH) and carboxymethyl cellulose (CMC) was studied on mangoes during postharvest storage at 15 °C for 20 days. Mangoes were coated with monolayers of CH (1 % w/v) and CMC (1 % w/v) as well as LBL application of CH and CMC and were compared with control. The treatment of mangoes with CH and CMC-based LBL treatment resulted in lower decay percentage and weight loss along with higher total chlorophyll pigments and suppressed total carotenoid accumulation. The LBL application of CH and CMC showed lower activity of chlorophyll degrading such as chlorophyllase (CPS), pheophytinase (Phe), Mg-dechalatase (MGD) and chlorophyll degrading peroxidase (Chl-POD) enzymes as well as reduced changes in b*, a* and L* along with a suppressed increase in ethylene (EP) and CO2 production (CPR) rates having higher antioxidant such as catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD) and superoxide dismutase (SOD) enzymes activity. In addition, mangoes coated with LBL treatment of CH and CMC exhibited lower water-soluble pectin (WSP) and higher protopectin (PP) having higher concentrations of chelate soluble (CSP) and sodium carbonate-soluble pectin (SCP). Similarly, LBL-coated mangoes showed significantly higher hemicellulose (HCLS) and cellulose (CLS) contents in contrast with control. It was observed that mangoes coated with CH and CMC-based LBL coating exhibited higher flesh firmness and showed suppressed cellulase (CS), pectin methylesterase (PME), polygalacturonase (PG) and β-galactosidase (β-Gal) enzymes activity. The concentrations of total soluble solids and ripening index were markedly lower and titratable acidity was higher in the LBL-based coating treatment in comparison with control. In conclusion, LBL treatment based on CH and CMC coatings could be used for the delay of ripening and softening of harvested mangoes.

Synergistic Utilization of ε-Polylysine and p-Coumaric Acid as Natural Preservatives for Enhancing the Shelf Life of Fresh-Cut Green Bell Peppers

The utilization of natural preservatives presents a promising avenue for mitigating the spoilage of fresh-cut fruits and vegetables induced by microorganisms, enzymatic browning, and water loss. We have developed an innovative method for preserving fresh-cut green peppers using the combined effects of ε-polylysine (ε-PL) and p-Coumaric acid (p-CA). Through concentration screening experiments, we determined that the optimal concentrations of ε-PL and p-CA were 25 mg/L and 10 mg/L, respectively (ε-p-CA). Treatment with ε-p-CA significantly improved the quality of fresh-cut green peppers. It effectively reduced hardness and weight loss, preserving the texture and appearance of the peppers. Furthermore, ε-p-CA treatment delayed the increase in respiratory rate, electrolyte leakage, and ethylene production, thereby maintaining the structural integrity. Meanwhile, ε-p-CA treatment effectively inhibited the malondialdehyde (MDA) content increase and maintained DPPH radical scavenging activity. The microbial analysis demonstrated the ε-p-CA-treated peppers also showed lower total bacterial, mold, and yeast counts, which prolonged the freshness of fresh-cut peppers. In addition, ε-p-CA treatment improved the retention of phenolics and vitamin C without significantly affecting the color and soluble sugar content of green peppers. Overall, the ε-p-CA treatment showed promise as a natural preservative for extending the shelf life of fresh-cut green peppers.

Ethylene production and antioxidant potential of five peach cultivars during maturation.

Numerous biochemical processes are involved in fruit maturation, such as ethylene production, phenolic compounds accumulation, and antioxidant enzymes production. Therefore, the aim of the present work was the evaluation of ethylene production, and the bioactive compounds change in the exocarp and mesocarp of five peach [Prunus persica (L.)] cultivars during three ripening stages, (1) early ripening (ER), (2) commercial maturation, and (3) full ripening (FR) in order to establish the best stage to harvest each peach variety. The experiment was applied to five peach cultivars growing within an arid bioclimatic environment covering the whole peach production season: two early cultivars, Flordastar and Early Maycrest; one variety of mid-season Rubirich; and two late cultivars, Sweet Cap and O'Henry. Ethylene production, phenolic compounds, and oxidative stress through antioxidant enzyme activities (catalase, peroxidases [PODs] Class III, and ascorbate-POD), malondialdehyde (MDA), and hydrogen peroxide (H2 O2 ) production were determined in the exocarp and mesocarp of peach fruits. The results showed a significant increase in ethylene production during fruit ripening. However, a parallel decrease in the level of phenolic compounds as well as in antioxidant enzyme activities was observed. The FR stage was also characterized by an important accumulation of MDA and H2 O2 . In conclusion, important changes in fruit quality associated with the production level of ethylene were observed. Fruits harvested during the ER stage would be more suitable for delivering to distant markets and more appreciated by the peach industries due to their highest phenolic acid content, best antioxidant enzyme activities, and lowest oxidative stress indicator.

Biomarkers of postharvest resilience: unveiling the role of abscisic acid in table grapes during cold storage.

Table grapes are considered non-climacteric fruit, not showing a rapid increase in respiration rate and ethylene production during ripening. Previous research has suggested that abscisic acid (ABA) may have a more crucial role in grape postharvest behaviour. This study aimed to identify biomarkers of postharvest resilience and flavour life of imported table grapes. An experiment was designed to determine i) the role of ABA and catabolites on grape berry senescence; ii) the spatial distribution of these hormones within the grape berry, and iii) the effect of 1-MCP and storage temperature on its postharvest quality. Hence, the use of an ethylene inhibitor, 1-methylcyclopropane (1-MCP), during table grape storage was investigated. Table grapes (Vitis vinifera L.) cv. 'Krissy' were subjected to i) control (untreated); and ii) 1-MCP (1 µL L-1; 12 hours; 15°C) and stored under two scenarios: i) 15 days at 0.5°C, followed by five days at 5.5°C to simulate shelf-life; and ii) 20 days at 5.5°C to simulate a higher storage temperature followed by shelf-life. Physiological (i.e. mould incidence, skin colour, firmness, respiration rate) and biochemical analysis (i.e. individual sugars, organic acids, abscisic acid and catabolites) were performed. Grapes subjected to 5.5°C showed significantly higher mould incidence at the end of the shelf-life compared to 0.5°C storage temperature (12.6% vs. 3.1%). Also, and for the first time, the spatial distribution of ABA during the senescence of table grapes was profiled; the distal section had three times more ABA and metabolites than the proximal. We demonstrated that senescence processes were initiated after a significant increase in respiration rate (from 1 to 2.8 mL CO2 kg-1 h-1), and that ABA could be considered a biomarker for table grapes senescence, since an ABA peak preceded the increase in respiration rate, mould incidence, organic acids, and sucrose hydrolysis during postharvest storage; and coincided with a decrease in berry firmness. These findings are of significant importance for the industry as understanding how ABA regulates both senescence processes and quality changes during postharvest cold storage of tables grapes can improve the consistency and reduce waste and consumer complaints.

Contrasting ethylene-mediated responses to waterlogging in four Eucalyptus globulus Labill. clones

We investigated the effects of overabundant watering in Eucalyptus globulus, a widely used species for pulp production with a low to moderate tolerance to waterlogging. We hypothesized that (1) overabundant watering would result stressful and trigger some of the well-known physiological responses to waterlogging and (2) different clones may show a different response to overabundant watering. Twelve potted plants from four E. globulus clones were watered with nozzles for twenty minutes, twice a day along 21 days. Other eight plants per clone were kept as controls and watered every two to four days. Overabundant watering caused a decrease in total leaf area after 21 days of treatment. Chlorophyll content and net photosynthetic rate were lower in plants under overabundant watering with no significant decrease in the rate of transpiration and no photoinhibition. Root pressure-generated xylem sap exudation was 3–17 times higher in plants under overabundant watering. We found significant differences between clones in ethylene production, growth, chlorophyll fluorescence parameters and root thickening. The highest increase in ethylene production was measured in clone c14, in which we measured the highest decrease in growth, chlorophyll content and the electron transport rate under overabundant watering. In conclusion, overabundant watering imposed a moderate stress, which allowed the plants to respond at the root and leaf level trying to drain the excess of soil water through transpiration. Our results support the viability of early testing for waterlogging resistance in Eucalyptus globulus clones, in order to select the best attributes to identify waterlogging-resistant genotypes.

1-MCP application in ‘Xuxiang’ kiwifruit at appropriate firmness avoids hard-core and prolongs the shelf life

The lack of synchrony in softening among the tissue zones and the increase in the production of autocatalytic ethylene lead to the hard-core and a short eating window in ready-to-eat kiwifruit. The present study analyzed the differences between the outer pericarp and the core during ripening to identify the cause of hard-core in ‘Xuxiang’ kiwifruit and aimed to maintain a soft texture and extend the eating window of ready-to-eat kiwifruit using 1-methylcyclopropene (1-MCP). Initial analysis showed that the outer pericarp had a few small spherical cells and many elongated cells, while the core had large homogeneous parenchyma cells. The core maintained higher firmness and cell wall polysaccharide content than the outer pericarp. During ripening, the pericarp followed a sigmoidal trend in softening, while the core followed a linear trend. We also found that the outer pericarp preceded the core in expressing the cell wall degradation-related and ethylene biosynthesis-related genes (AcXET1, AcEXP1, AcPG, AcPL2, AcACS1, and AcACO2). Moreover, the increase in ethylene production was highly correlated with the decrease in core firmness. These differences between the outer pericarp and the core probably led to the hard-core in kiwifruit. Subsequent texture analysis and sensory evaluation revealed 75–100 N as the acceptable core firmness limit for ‘Xuxiang’ kiwifruit. The fruit treatment experiments based on these observations showed that applying 1-MCP on ready-to-eat ‘Xuxiang’ kiwifruit at ∼12 N firmness resulted in best preservation, with an extra 15 d of shelf life and an acceptable core firmness. In conclusion, these findings suggest that treating ‘Xuxiang’ kiwifruit at ∼12 N firmness after harvest with 1-MCP will help avoid hard-core and prolong the eating window, improving consumer acceptance.

Impact of Cold Storage Temperature and Shelf Life on Ripening Physiology, Quality Attributes, and Nutritional Value in Apricots-Implication of Cultivar.

This work aimed to investigate the storability potential of Orange Red and Orange Rubis apricots harvested at commercial maturity stage during cold storage (CS) at 1 or 5 °C for up to 28 days, followed by shelf life (SL) at 20 °C for 2 days. The variables evaluated included total soluble solids, titratable acidity, pH only at harvest, weight loss (WL), ethylene production rates, peel color, firmness, chilling injury incidence (CI), concentrations of total phenolics, flavonoids, carotenoids, total antioxidant capacity, b-carotene, b-cryptoxantine, and lutein. The main results showed that storage at 5 °C resulted in higher WL and CI symptoms than at 1 °C during both CS and SL, increased ethylene production during CS, whereas there was limited or no effect of CS temperatures on changes in firmness, color, and all antioxidants during CS. Firmness decreased abruptly soon after harvest in Orange Rubis, but progressively in the remaining samples of both cultivars during CS and SL. SL advanced fruit deterioration according to WL, CI, and softening. During SL, ethylene production increased in all samples. Orange Red exhibited higher ethylene rates during SL and antioxidant concentrations throughout CS and SL, by comparison. Conclusively, storage temperature at 1 °C retained WL, CI, and ethylene production, and both cultivars were marketable up to 21 days CS without SL or up to 14 days CS followed by SL, although Orange Rubis exhibited CI after 14 days, while Orange Red exhibited CI after 21 days of CS.

Firmness prediction of 'Rocha' pear based on non-destructive methods and shelf-life using PLS-regression modeling

Knowledge of fruit firmness in the distribution chain is essential for stakeholders, including producers, agri-food industries, and consumers. In recent years, there has been a general interest in predicting ripening-related firmness with non-destructive techniques. The objective of this study was to create a model, based on non-destructive methods that assess directly critical physiological parameters and quality attributes related to ripening, along with shelf-life time, to predict firmness of 'Rocha' pear (Pyrus communis L.), a protected designation of origin (PDO) commodity. Hereto, pear firmness profile was assessed for ten days at room temperature, after removal from different storage periods at cold conditions. Ripening was evaluated based on color alterations, ethylene production, and respiration rate. Pear firmness decreased drastically over time, concomitant with the yellowing of the fruit skin and increased ethylene production and respiration rate. These characteristics and shelf-life time were correlated with firmness by applying the Partial Least Squares (PLS) procedure to develop a mathematical model for predicting pear firmness during ripening. The model explained 89 % of the firmness variance during ripening and, after validation, showed high accuracy (R2 = 0.87). To the best of our knowledge, this is the first time that these physiological parameters, directly related to ripening-firmness, have been used to predict pear firmness using non-destructive measurements of the samples.