Development of Blueberry-Derived Extracellular Nanovesicles for Immunomodulatory Therapy

Over the past decade, there has been a significant expansion in the development of plant-derived extracellular nanovesicles (EVs) as an effective drug delivery system for precision therapy. However, the lack of effective methods for the isolation and characterization of plant EVs hampers progress in the field. To solve a challenge related to systemic separation and characterization in the plant-derived EV field, herein, we report the development of a simple 3D inner filter-based method that allows the extraction of apoplastic fluid (AF) from blueberry, facilitating EV isolation as well as effective downstream applications. Class I chitinase (PR-3) was found in blueberry-derived EVs (BENVs). As Class I chitinase is expressed in a wide range of plants, it could serve as a universal marker for plant-derived EVs. Significantly, the BENVs exhibit not only higher drug loading capacity than that reported for other EVs but also possess the ability to modulate the release of the proinflammatory cytokine IL-8 and total glutathione in response to oxidative stress. Therefore, the BENV is a promising edible multifunctional nano-bio-platform for future immunomodulatory therapies.

A Synergistic Effect Based on the Combination of Melatonin with 1-Methylcyclopropene as a New Strategy to Increase Chilling Tolerance and General Quality in Zucchini Fruit

Zucchini fruit are highly sensitive to low temperatures leading to significant peel depressions, increasing weight loss and making them impossible to be commercialized. In this study the effect on the reduction of chilling injury (CI) assaying different postharvest treatments to cv. Cronos was evaluated. We have compared the application of substances such as 1-methylcyclopropene (1-MCP) with the application of a natural origin compound as melatonin (MT), both with demonstrated activity against CI in different vegetal products. The effects of MT (1 mM) by dipping treatment of 1 h and 1-MCP (2400 ppb) have been evaluated on zucchini fruit during 15 days of storage at 4 °C plus 2 days at 20 °C. Treatments applied independently improved some fruit quality parameters in comparison with control fruit but were not able to manage CI even though they mitigated the impact on several parameters. However, when these two separated strategies were combined, zucchini cold tolerance increased with a synergic trend. This synergic effect affected in general all parameters but specially CI, being also the only lot in which zucchini fruit were most effectively preserved. This is the first evidence in which a clear positive effect on zucchini chilling tolerance has been obtained combining these two different strategies. In this sense, the combined effect of 1-MCP and MT could be a suitable tool to reach high quality standards and increasing shelf life under suboptimal temperatures.

Combined Transcriptome and Metabolome Analysis of Musa nana Laur. Peel Treated With UV-C Reveals the Involvement of Key Metabolic Pathways

An increasing attention is being given to treat fruits with ultraviolet C (UV-C) irradiation to extend shelf-life, senescence, and protection from different diseases during storage. However, the detailed understanding of the pathways and key changes in gene expression and metabolite accumulation related to UV-C treatments are yet to be explored. This study is a first attempt to understand such changes in banana peel irradiated with UV-C. We treated Musa nana Laur. with 0.02 KJ/m2 UV-C irradiation for 0, 4, 8, 12, 15, and 18 days and studied the physiological and quality indicators. We found that UV-C treatment reduces weight loss and decay rate, while increased the accumulation of total phenols and flavonoids. Similarly, our results demonstrated that UV-C treatment increases the activity of defense and antioxidant system related enzymes. We observed that UV-C treatment for 8 days is beneficial for M. nana peels. The peels of M. nana treated with UV-C for 8 days were then subjected to combined transcriptome and metabolome analysis. In total, there were 425 and 38 differentially expressed genes and accumulated metabolites, respectively. We found that UV-C treatment increased the expression of genes in secondary metabolite biosynthesis related pathways. Concomitant changes in the metabolite accumulation were observed. Key pathways that were responsive to UV-C irradiation include flavonoid biosynthesis, phenylpropanoid bios6ynthesis, plant-pathogen interaction, MAPK signaling (plant), and plant hormone signal transduction pathway. We concluded that UV-C treatment imparts beneficial effects on banana peels by triggering defense responses against disease, inducing expression of flavonoid and alkaloid biosynthesis genes, and activating phytohormone and MAPK signaling pathways.

Temperature regulation of plant hormone signaling during stress and development

Global climate change has broad-ranging impacts on the natural environment and human civilization. Increasing average temperatures along with more frequent heat waves collectively have negative effects on cultivated crops in agricultural sectors and wild species in natural ecosystems. These aberrantly hot temperatures, together with cold stress, represent major abiotic stresses to plants. Molecular and physiological responses to high and low temperatures are intricately linked to the regulation of important plant hormones. In this review, we shall highlight our current understanding of how changing temperatures regulate plant hormone pathways during immunity, stress responses and development. This article will present an overview of known temperature-sensitive or temperature-reinforced molecular hubs in hormone biosynthesis, homeostasis, signaling and downstream responses. These include recent advances on temperature regulation at the genomic, transcriptional, post-transcriptional and post-translational levels - directly linking some plant hormone pathways to known thermosensing mechanisms. Where applicable, diverse plant species and various temperature ranges will be presented, along with emerging principles and themes. It is anticipated that a grand unifying synthesis of current and future fundamental outlooks on how fluctuating temperatures regulate important plant hormone signaling pathways can be leveraged towards forward-thinking solutions to develop climate-smart crops amidst our dynamically changing world.

Effects of ethrel, 1-MCP and modified atmosphere packaging on the quality of 'Wonderful' pomegranates during cold storage

BACKGROUND

Pomegranate (Punica granatum) is a non-climacteric fruit susceptible to chilling injury (CI) at temperatures below 5 °C. To understand the influences of ethylene and modified atmosphere on CI physiological disorders of pomegranate, exogenous ethrel (0.5, 1 and 1.5 µg L^-1 ) treatments, 1-methylcyclopropene (1-MCP) (1 µL L^-1 ) exposure, packaging in a modified atmosphere (MAP) (XTend™ bags; StePac, São Paulo, Brazil), a MAP/1-MCP combination, and packaging in macro-perforated bags (MPB) were applied. The treated fruits were cold stored (2 ± 1 °C; 85% relative humidity) and sampled during 120 + 3 days at 20 °C.

RESULTS

During cold storage, CI symptoms started at 20 days in MPB and at 60 days for all exogenous ethylene treatments, and were delayed to 120 days in MAP, 1-MCP and MAP/1-MCP treatments. MPB and ethylene treatments induced significant electrolyte leakage, oxidative damage, lipid peroxidation, ethylene and CO₂ production, and 1-aminocyclopropane-1-carboxylic acid oxidase activity, without any change in total soluble solids, titratable acidity or skin and aril colours. Conversely, MAP by itself, or in combination with 1-MCP application, effectively delayed CI symptoms.

CONCLUSION

During long-term cold storage of this non-climacteric fruit, ethrel application induced endogenous ethylene biosynthesis, accelerating the appearance of CI symptoms in contrast to the observations made for MAP and 1-MCP treatments. © 2018 Society of Chemical Industry.

Expression Profiles and DNA-Binding Affinity of Five ERF Genes in Bunches of Vitis vinifera cv. Cardinal Treated with High Levels of CO2 at Low Temperature

Ethylene response factors (ERFs) play an important role in plants by regulating defense response through interaction with various stress pathways. After harvest, table grapes (Vitis vinifera L.) are subject to a range of problems associated with postharvest storage at 0°C, such as fungal attack, water loss and rachis browning. The application of a 3-day high CO₂ treatment maintained fruit quality and activated the induction of transcription factors belonging to different families such as ERF. In this paper, we have isolated five VviERFs from table grapes cv. Cardinal, whose deduced amino acid sequence contained the conserved apetalous (AP2)/ERF domain. The phylogeny and putative conserved motifs in VviERFs were analyzed and compared with those previously reported in Vitis. VviERFs-c gene expression was studied by quantitative real-time RT-PCR in the different tissues of bunches stored at low temperature and treated with high levels of CO₂. The results showed that in most of the tissues analyzed, VviERFs-c gene expression was induced by the storage under normal atmosphere although the application of high levels of CO₂ caused a greater increase in the VviERFs-c transcript accumulation. The promoter regions of two PRs (pathogenesis related proteins), Vcchit1b and Vcgns1, were obtained and the in silico analysis revealed the presence of a cis-acting ethylene response element (GCC box). In addition, expression of these two PR genes was analyzed in the pulp and rachis of CO₂-treated and non-treated table grapes stored at 0°C and results showed significant correlations with VviERF2-c and VviERF6L7-c gene expression in rachis, and between VviERF11-c and Vcchit1b in pulp. Finally by using electro mobility shift assays, we denoted differences in binding of VviERFs to the GCC sequences present in the promoters of both PRs, with VviERF6L7-c being the only member which did not bind to any tested probe. Overall, our results suggest that the beneficial effect of high CO₂ treatment maintaining table grape quality seems to be mediated by the regulation of ERFs and in particular VviERF2-c might play an important role by modulating the expression of PR genes.