Fruit Quality Attributes of ‘Arisoo’ and ‘Picnic’ Apples as Influenced by 1-Methylcyclopropene Concentration and Its Application Frequency during Cold Storage

The efficacy of 1-methylcyclopropene (1-MCP) in maintenance of apple fruit quality can differ depending on apple cultivar, ethylene content at harvest, 1-MCP concentration, the interval between harvest and 1-MCP application, and the number of applications. In this study, we investigated whether the 1-MCP concentration and its application frequency differently affected fruit quality attributes of the two new apple cultivars ‘Arisoo’ and ‘Picnic’. The fruits were treated with 1-MCP (as single or double treatments) at the rate of 0 μL L−1 (control), 0.5 μL L−1, 1 μL L−1, 0.5 + 0.5 μL L−1, and 1 + 1 μL L−1 for 18 h, and they were stored at 0 °C up to six months. Comparatively, the fruit qualities of 1-MCP treated fruits were higher than that of the control during cold storage, with a higher suppression of internal ethylene content and a slower reduction of titratable acidity in 1-MCP treatments than the controls throughout the cold storage in both cultivars, regardless of the concentration and number of applications. Reduction of fruit firmness and soluble solid contents were maintained by single application of 0.5 μL L−1 1-MCP in ‘Arisoo’ apple, while double application of 0.5 + 0.5 μL L−1 was needed in ‘Picnic’ cultivar. The effective concentration for weight-loss reduction was found to be the single application of 1 μL L−1 1-MCP in both ‘Arisoo’ and ‘Picnic’. Conclusively, 1-MCP as single treatment at the rate of 0.5 μL L−1 could be sufficient in inhibiting ethylene action and maintaining fruit quality losses during cold storage, particularly in ‘Arisoo’. However, double application of 1-MCP might be necessary for some quality attributes in ‘Picnic’ apple.

Wear Analysis of Materials Used for a Track Steering System in Abrasive Soil Mass

This paper presents the results of comparative research on materials used for a track steering system in an abrasive soil mass. Two types of elastomer tracks were tested: a steel-rubber stave from an asphalt paver and a rubber overlay used in vehicles with a steel track chain. The results obtained were related to the wear of Hadfield steel. The tests were carried out on a “spinning bowl” stand in a natural soil mass, which consisted of two types of soil: light and heavy. It was shown that the resistance to abrasive wear depended on the grain size of the worked soil and the chemical composition of the materials. Rubber overlay was found to have the highest resistance index in all types of soils. It was made of high-density polyethylene, low-density polyethylene, ethylene acrylate/ethyl copolymer (ethylene acrylate 18%) and ethylene/propylene copolymer with an ethylene content of 60%. An analysis of the condition of the machined surfaces after friction tests complements the results presented.

Crosstalk between Ethylene and ABA during changes in soil water content reveals a role of ACC in coffee anthesis regulation

Coffee (Coffea arabica L.) presents an asynchronous flowering regulated by endogenous and environmental stimulus, and anthesis occurs once plants are rehydrated after a period of water deficit. We evaluated the evolution of Abscisic Acid (ABA), ethylene, 1-aminocyclopropane-1-carboxylate (ACC) content, ACC oxidase (ACO) activity, and expression analysis of the Lysine Histidine Transporter 1 (LHT1) transporter, in roots, leaves and, flower buds from three coffee genotypes (Coffea arabica L. cv Oeiras, Acaua, and Semperflorens) cultivated under field conditions with two experiments. In a third field experiment, the effect of exogenous supply of ACC in coffee anthesis was evaluated. We found an increased ACC level in all tissues from the three coffee genotypes in the re-watering period just before anthesis for all tissues and high expression of the LHT1 gene in flower buds and leaves. Ethylene content and ACO activity decreased from rainy to dry period whereas ABA content increased. Higher number of opened and G6 stage flower buds were observed in the treatment with exogenous ACC. The results showed that the interaction of ABA-ACO-ethylene and intercellular ACC transport among leaves, buds, and roots in coffee favors an increased level of ACC that is most likely, involved as a modulator in coffee anthesis.

Stablization of ACOs by NatB mediated N-terminal acetylation is required for ethylene homeostasis

N-terminal acetylation (NTA) is a highly abundant protein modification catalyzed by N-terminal acetyltransferases (NATs) in eukaryotes. However, the plant NATs and their biological functions have been poorly explored. Here we reveal that loss of function of CKRC3 and NBC-1, the auxiliary subunit (Naa25) and catalytic subunit (Naa20) of Arabidopsis NatB, respectively, led to defects in skotomorphogenesis and triple responses of ethylene. Proteome profiling and WB test revealed that the 1-amincyclopropane-1-carboxylate oxidase (ACO, catalyzing the last step of ethylene biosynthesis pathway) activity was significantly down-regulated in natb mutants, leading to reduced endogenous ethylene content. The defective phenotypes could be fully rescued by application of exogenous ethylene, but less by its precursor ACC. The present results reveal a previously unknown regulation mechanism at the co-translational protein level for ethylene homeostasis, in which the NatB-mediated NTA of ACOs render them an intracellular stability to maintain ethylene homeostasis for normal growth and responses.

Influences of sea water on the ethylene-biosynthesis, senescence-associated gene expressions, and antioxidant characteristics of Arabidopsis plants

We evaluated the physiological and antioxidant characteristics of Arabidopsis thaliana (At) plants grown in different sea water (SW) products containing trace elements, namely RO3, 300K, and 340K, at various dilutions. The synthetic water (namely 300K-Test), a mixture of the main ions of SW including 143.08 mg L-1 Mg2+, 5.74 mg L-1 Na+, 170 mg L-1 K+, and 33.5 mg L-1 Ca2+ with equal concentrations to those in 300K SW without trace elements, was also used to culture At plants and study the influences that the major ions had on regulating ethylene production. The ethylene-biosynthesis (ACS7 and ACO2) and senescence-associated (NAP, SAG113, and WRKY6) gene expressions in SW- and ionic-treated At plants in response to transcriptional signaling pathways of ethylene response mechanisms were also investigated. Our results show that down-regulation of the ACS7 gene in 300K-treated plants significantly reduced the ethylene content but remarkably increased chlorophyll, total phenol, and DPPH radical scavenging accumulations and strengthened the salt tolerance of 300K-treated plants. The expression of the ACS7 gene of At plants under 300K, Ca2+, Mg2+, and Na+ treatments was correlated with decreases in NAP, SAG113, and WRKY6 gene expressions. The application of Ca2+ increased total phenol content and reduced the accumulation of superoxide, which in combination decreases plant aging brought on by ethylene. However, K+ treatment inhibited SGA113 gene expression, resulting in reducing ACS7 gene expression and ethylene content. The characterization and functional analysis of these genes should facilitate our understanding of ethylene response mechanisms in plants.

New, Aqueous Radical (Co)Polymerization of Olefins at Low Temperature and Pressure

In this communication, we describe our preliminary results for the development of a new method of ethylene and propene (co)polymerization at low pressure at room temperature, using cyclodextrin-assisted aqueous radical polymerization for the first time. For polypropylene homopolymerization, the cyclodextrin was entirely removed, and the partially soluble polymer was characterized. The purification of polyethylene was not complete, since the threaded cyclodextrins remained on the polymer chain, enhancing its solubility and enable to analyze the sample. With this environmentally benign method, polyolefines could be produced, for the first time. The estimated yield was low, and therefore the conditions should be further tuned for industrial application. This straightforward approach could also be applied to synthesize poly(ethylene-co-vinyl acetate) copolymer with an ethylene content of 20 mol% and enhanced yield. Although the procedure in this stage of research has some limitations, the theory behind can later be applied to develop new, energy-efficient, and versatile industrial processes for olefin copolymerizations for a wide range of comonomers.

Analysis of Possibility to Apply Preharvest 1-Methylcyclopropene (1-MCP) Treatment to Delay Harvesting of Red Jonaprince Apples

The production of Red Jonaprince cultivar is increasing, but the quality of apples is still challenging. Therefore, various options may be used including 1-Methylcyclopropene (1-MCP) application, as it influences ethylene receptors and blocks them, resulting in the possibility of delaying harvesting. The preharvest application of 1-MCP has not been studied so far for this cultivar but for other ones it has been successful, as it is based on the understanding of the natural apple ripening process. The study aimed to analyze the possibility of applying a 1-MCP treatment in the preharvest period for Red Jonaprince apples. The study was conducted based on a comparison of apples from two groups of Red Jonaprince apple trees (4 years) cultivated in an experimental orchard, where for one of them 1-MCP was applied in the preharvest period (HarvistaTM; 150 g per ha; 20 September—12 days before the optimum harvesting window (OHW)). For both groups, the apples were studied twice, for harvesting in the OHW (2 October) and for delayed harvesting (24 October). The harvested fruits were stored in an Ultra Low Oxygen chamber (ULO; 1.2% CO2, 1.2% O2) until May. They were analyzed before storage (preharvest) five times (20 September–24 October) and after storage (postharvest) three times (20 March–18 May). The following parameters were included: firmness, total soluble solids (TSS) content, titratable acidity (TA). For the preharvest period, the parameters also included internal ethylene content (IEC), starch index, and Streif index. For the preharvest period, significant differences associated with the 1-MCP treatment (p ≤ 0.05) were observed for the IEC (lower results for apples treated for 4th and 5th assessment), TA (higher results), and Streif index (higher results). Meanwhile, for firmness, TSS, and starch index for the majority of measurements there were no differences (p > 0.05). For the postharvest period, significant differences associated with 1-MCP treatment (p ≤ 0.05) were observed for firmness (higher results) and TA (higher results) both for OHW and delayed harvesting. It was concluded that a preharvest 1-MCP treatment allowed delayed harvesting and reduced the quality deterioration during the ULO storage of Red Jonaprince apples.

The Effects of Preharvest 1-Methylcyclopropene (1-MCP) Treatment on the Fruit Quality Parameters of Cold-Stored ‘Szampion’ Cultivar Apples

Postharvest treatment by 1-methylcyclopropene (1-MCP) for ‘Szampion’ cultivar apples inhibits ripening of climacteric fruit by blocking ethylene receptors, preventing ethylene from binding and eliciting its action. It is also possible to apply 1-MCP preharvest, which so far has not been studied for the ‘Szampion’ cultivar. The aim of this study was to assess the effects of preharvest 1-MCP treatment on the fruit quality parameters of cold-stored ‘Szampion’ cultivar apples in a Polish experiment. Two identical groups of apple trees (6 years, experimental orchard in Warsaw) were included, to obtain studied apples (preharvest 1-MCP treatment with HarvistaTM, 150 g/ha, 7 days before the optimum harvesting window, OHW) and control apples (1-MCP not applied). Apples for the studied group were harvested twice—on 28 September (OHW) and 24 October (delayed harvesting)—and for control group once—on 28 September, as before 24 October the majority of apples fell from trees. Afterwards, apples were stored in an Ultra Low Oxygen chamber (1.2% CO2, 1.2% O2). Apples were assessed in the preharvest period (weekly, six measurements for the studied group, and five measurements for the control group) and postharvest period (monthly, three measurements separately for each harvest time for the studied group and control group). The following parameters were assessed: internal ethylene content (IEC), firmness, total soluble solids (TSS) content, starch index, Streif index, titratable acidity (TA), and color for blush. For the preharvest period, statistically significant differences between the studied group and the control group were observed for IEC, the a* coordinate of color (p < 0.05; for apples treated with 1-MCP lower results), firmness, Streif index, TA (p < 0.05; higher results), and starch index (p < 0.05; no defined trend). For the postharvest period, statistically significant differences between the studied group and the control group were observed for apples harvested in the OHW for firmness (p < 0.05; for apples treated with 1-MCP higher results) and IEC (p < 0.05; no defined trend), while for delayed harvesting the differences were only minor. It may be concluded, that preharvest 1-MCP application makes it possible not only to obtain better results for ‘Szampion’ cultivar apples’ quality parameters, but also allows delayed harvesting without deterioration in quality.

Exogenous Application of Sucrose Promotes Postharvest Ripening of Kiwifruit

Sucrose is an important component of fruit flavor, but whether sucrose signaling affects the postharvest ripening process of kiwifruit is unclear. The aim of this article was to study the effect of sucrose application on postharvest kiwifruit ripening to clarify the effect of sucrose in this process. Our present study found that exogenous sucrose can promote ethylene synthesis, which increases the ethylene content during fruit ripening, thereby accelerating the ripening and softening of kiwifruit after harvest. A significantly higher expression of AcACS1 and AcACO2 was found in sucrose-treated fruits compared to that in mannitol-treated fruits. Blocking the ethylene signal significantly inhibited the sucrose-modulated expression of most selected ripening-related genes. Sucrose transport is essential for sucrose accumulation in fruits; therefore, we isolated the gene family related to sucrose transport in kiwifruit and analyzed the gene expression of its members. The results show that AcSUT1 and AcTST1 expression increased with fruit ripening and AcSUT4 expression decreased with ripening, indicating that they may have different roles in the regulation of fruit ripening. Additionally, many cis-elements associated with phytohormones and sugar responses were found in the promoter of the three genes, which suggests that they were transcriptionally regulated by sugar signal and phytohormones. This study demonstrates the effect of sucrose on postharvest ripening of kiwifruit, providing a good foundation for further research.